Harold, I notice you almost always recommend going with a larger fuel line when installing your stout cams. Say 1/2" dia. I just wonder why no other cam manufacturer recommends this. Is it because you know something they aren't telling us, or your cam grinds require more fuel (BSFC) to optimize their performance? I'm bitting the bullet and switching from CC's XE284 hyd flat to one of your solid rollers. Just wondering what other mods I'll need to do. Thanks, Tony A. graemlins/beers.gif

I'd like to know the answer to this one too,since Ed is running mid/low 10's with a 3/8 fuel line. And he used to run an Ultradyne cam.

chevywidow, the xe284 is whats going in my 506, how do you like it, what are your ets, your combo?
thanks- aubrey

Aubrey, good day! That cam is in my 439" with GMPP Alum. heads and bow tie dual plane intake with a Demon 750 D.P. Weight is 3770 with driver. My best was 11.988 @ 112.48, thats with 4.11 and 10.5x28 MT ET Drag. The cam is noisy like everyone reports and because it's hydraulic, falls off at 6000 rpm. It has a rumpty idle and makes 10.5" vacuum @ 900 rpm (in park). Want to buy used and avoid the break-in? Perhaps my 3/8" line is slowing me down. I bet it would be a good street cam in that 506". Tony A.

That is because a lot of cars are fuel starved and he wants to make sure yours is not. When I ordered a cam for my 502 in 55 Chev, he told me to make sure I had lots of fuel. I was'nt to concerned about it and told him of the stock ZL-1 in my Camaro that was running a 3/8 fuel line with a stock GM pump. It was going 113 mph through the exhaust manifolds! He told me to upgrade the fuel system on it. I never ever felt the car nose over, so did not think it was a problem. The next time at the track, I brought a Holley mech. pump and changed it at the track after three 113 mph runs. The first pass it went 116mph!!!!!! No other change!!!!!!! graemlins/clonk.gif
Peter

Robert, you knew Harold wouldn't touch this post when you mentioned the arse from NJ? If not, I apologize. If you did know, shame on you. If you hadn't noticed, we don't care what that guy says at all anymore. And Harold won't come near a post with "the namecaller". Still, congrats on your top ten, that's very cool. Yet, don't prostitute yourself here.

And the answer to the question to quote Mr. Brookshire.....

"

We are talking about air/fuel ratio here, and you obviously need the correct A/F ratio to make peak horsepower. About 26 YEARS of experience designing unsymetrical cams, 1st for Competion Cams(They still sell some of my original cams today!), then for UltraDyne, has shown me that at high-RPM the unsymetrical cam(the way I design it) flows a lot more, and cleaner, air, than the typical camshaft. All engines respond to this by going LEAN on the top-end if there is insufficient fuel for the available air.
Because I design all my cams, hydraulic, solid, roller, etc, similarly, over a certain BHP number they start showing this problem.
You can get my SB288/296R9, put it in like I said, and run it with just your one Mallory 140. If about 5500-6000, the engine quits pulling and goes very flat, you know that I will say it's running out of gas. The cam is pulling gas through the jets faster than the one pump is supplying to the float bowls. This is not a jetting problem, but a fuel volume/supply problem. Engines have been responding to the dual pumps for about 26 years, although the new breed of 250+ GPH pumps need only one pump. The 1/2" #8 line is also a necessity.
Please note the valve timing: When you put the intake lobe in at 102° ATDC by the lobe-centerline method, the intake opens at 39° BTDC. Everyone will tell you that is at 105° intake CL, and they are correct too. When the majority of this cam is at 102° ATDC, after top-dead center, this cam is at 105° at .020", and at 103.5° at .050". This is part of its' secrets(only part...)."

Guys, keep in mind Harold is a professional cam designer and quite busy. I encourage you to use the search function when applicable and run the searches only here in Performance under Harold's reg tech team number # 12554.

(And yes, on an unsolicted basis, I'm trying to be his 'body guard', since I promised him he wouldn't have to deal with trolls here at Team Chevelle. We are fortunate to have him drop by once in a while and I'm always 'locked and loaded' and apologize in advance for being a paranoid- just my nature.)

Gene ..... excellent response re Harolds fuel line rationale ,like COPO Pete says in a lot of cases fuel volume is more the issue than pressure I,ve been there too ( Turbo Buick)...go the big line!!!

maybe dumb question but !/2 " fuel line is always mentioned and most associate AN 8 with 1/2" but big fuel pumps like the Carter 172 comes with AN 10 inlet fitting which is 5/8 od 9/16" id so my 66 project getting 5/8 od line and tank pickup some have told me too big pump won't pull that volume ......I disagree ???

Man, I'm still running a 3/8" and a "stock" AC pump, what do I know? graemlins/clonk.gif All I've done is eliminate some 'kinks' near the tank. Pressure seems fine, but I understand it's VOLUME not pressure.

I keep an eye on my fuel pressure gauge at the top end. The original stock pump with 3/8" lines started out at 7psi at the starting line and dropped to 2 psi going through the traps. I put the big Carter mech pump in and retained the 3/8" line. Fuel pressure starts at 8psi and ends up at 7psi. As long as I have sufficient pressure, my line size is adequate, correct? I measure the fuel pressure right before the bowl. Just my $.02 and observations

FWIW ..... I have a fwd grand prix with Supercharged V6 running in the high 12's and although fuel pressure was good at redline I was going lean and detonating at max boost increasing pressue did not help, made changes to increase volume, Bingo!!

Originally posted by Epistuff:
I keep an eye on my fuel pressure gauge at the top end. The original stock pump with 3/8" lines started out at 7psi at the starting line and dropped to 2 psi going through the traps. I put the big Carter mech pump in and retained the 3/8" line. Fuel pressure starts at 8psi and ends up at 7psi. As long as I have sufficient pressure, my line size is adequate, correct? I measure the fuel pressure right before the bowl. Just my $.02 and observations Usually you want to watch fuel pressure between shifts 1-2 and 2-3, most cars shift at a higher rpm than what the car is going thru the traps at the end. again I said most. graemlins/thumbsup.gif

maybe dumb question but !/2 " fuel line is always mentioned and most associate AN 8 with 1/2" but big fuel pumps like the Carter 172 comes with AN 10 inlet fitting which is 5/8 od 9/16" id so my 66 project getting 5/8 od line and tank pickup some have told me too big pump won't pull that volume ......I disagree ??? For that same reason I ran -10 all the way from the sump in my tank to the pump, from the pump to the fuel log -8 and a 1/2" Aeroquip Fuel Log. It does get expensive though, when I got started I didn't have a clue as to how expensive that stuff is. My Carter 172gph pump does fine with that big of line. I don't think the male AN would be a -10 if it wouldn't work. Works fine for me though.

Matt

Matt, Thanks for that ......... good point doing an AN 10 fuel line can get expensive but I only want to do it once and should not have to spend $$ on electric pumps so total cost should not be too bad........ Bill

I'm running a very mild set up that was falling on its face in high gear. I had a 1/2 line from the cell to the reg. with cheap 3/8 fittings and line to the carb. I got some good 1/2 fitting and line from the reg. to the carb and went from a 107 mph to a 112 mph.

First off, is there a downside to running 1/2" even if you dont have to??? Its not going to be any harder to run, and its simply a precautionary. Anyone have any down sides to it that youve heard of???

Yea I hear its a noisy cam too. I already have one ordered for my 506 getting built, it'll be a daily driven car, but im going to race it. The engine is supposed to make peak horsepower at 6500 rpm, I probably wont need power past that will I? is your cam the .574/.578 lift, 240/246 at .050 (just making sure thats what the xe284 is, in case I got confused with it's name)? Would you consider this a mild-ish cam, I didn't think it was but I see other people here, big and small blocks, turning 10-11 sec times (what I hope for) with much bigger cams, usually solid rollers. What kind of application is this cam best for? Should I run a 1/2" fuel line too? Sorry about all the questions, trying to learn this stuff. thank you - Aubrey

I was just using Ed as an example Gene,nothing more nothing less. There are not as many on this board that do more with less as Ed does or quite as free flowing with information about their combo,or has a combo that is so stock appearing. I know he has a trick rear suspension,although its bolt in. But the performance of his car just flat out impresses me. I wasnt trying to ruffle any feathers. As for me,I'm still using the 3/8's fuel line also, with a carter mechanical and a comp 140 which is probably blowing right throught it, I just havent got around to removing the mechanical pump,just have to hook the AN line up to the 3/8 fuel line.

It's a nice looking race car Bob, that's for sure. Thought it looked like 1/2" line under the hood when I saw the car last year though. Todd, Kenny, Pat and a few others are running roughly the same times.

I was thinking of mounting a Holley blue in back to push through my stock AC. Switched through a relay. On demand only. Wonder if its even worth the effort through 3/8 steel line though. Would be an easy test to see if mph picks up. Sure would like to run 120+! smile.gif

Originally posted by Epistuff:
Fuel pressure starts at 8psi and ends up at 7psi. As long as I have sufficient pressure, my line size is adequate, correct? I measure the fuel pressure right before the bowl. Just my $.02 and observations For your car yes but as a general answer to everyone no. It is still possible to have good pressure and have to bowls running dry because of lack of volume. Pressure is always created by a restriction ( needle and seat, fuel fittings, line size, fuel filter, ect...) Since there isn't any practical way of measuring the fuel level in a carb while running the 1/4, going a little bigger in a fuel system doesn't hurt just to make sure the volume capacity is there. This is especially true if a power adder is used

When the 383 was in my Camaro, I could pull 1.6x 60' times. But, I'd only gain 8-10 mph between the 1/8 mile marker and the end of the 1/4. The car would physically run out of gas (stall) by the time I got to the turn off.
I tried all the different "hi output" mechanical pumps on the stock 3/8" line.
Finally, swapped in 1/2" fuel line from the stock tank pickup and installed a Holley "blue" pump. No more problems and the car ran 113 mph in the 1/4.
And yes, Harold did tell me over the phone that I'd need TWO Mallory 140's in the Chevelle to feed this new cam recently purchased. :D

RapidRobert,

I don't miind answering this question, as I have repeated it every working day for 23 years.
1st, NO ONE has ever told me they have SLOWED DOWN when they increased the volume of the fuel system the way I told them to. And I've never made a cent off of selling them 'trick fuel systems'.
2nd, THOUSANDS, or tens of thousands, have told me they've picked up. A lot of them have been running the BB288/296H10, the same cam that Ed, aka racer1320, has run. The difference is that I tell them to run the cam 6° advanced, and when they do, they see that they need the bigger fuel system to keep the float bowls filled up around peak power. Ed refused to change his 3/8" line and 1 Mallory 140 pump, he was told that that set-up was enough. He found out that the BB288/296H10 ran best 2° RETARDED, and the other 4 or 5 thousand customers found that it ran the best 6° advanced, and with a better fuel system. Ed did wonders with that cam, and I thank him for telling people about it.
I claim that my cams make a broad range of torque, it takes fuel to do that. I claim that at high-RPMs, my cams have LESS reversion than normal cams, and this allows them to flow more, and cleaner, air, therefore demanding MORE fuel, rather than having to be leaned out for power. Because my cams used a lot of fuel making torque in the mid-range, the fuel system MUST be capable of meeting the VOLUME demand at high-RPM. It takes a good fuel system to do that.
BTW, the cams are not wasteful of fuel. My smaller hydraulics give excellent fuel economy, particularly in applications requiring a lot of torque, such as duallies towing race-cars, or motorhomes. In racing, after the 1980 Daytona 500 Bobby Allison, the 2nd place finisher, claimed that Buddy baker beat him because Buddy got better fuel economy. The 1980 Daytona 500 is the FASTEST Daytona 500 ever run. And the 1986 24 Hours of Daytona's GTP/L class was won by a Fiero-engined sportscar. Pontiac had told me that if they could make 6 MPG, they had a chance of winning. In 24 hours they went 2330 miles, and averaged over 8.6 MPG.
My designs use gas to make power, not to waste gas. This is enough. I literally have thousands of stories about picking up, particularly at the drag strip, where you have to supply enough fuel, and you only have 6 to 12 seconds to do it.
BTW, other companies do not design cams the way I do, and they do not make these claims. They know what is best for THEIR cams, and I know what is best for mine.

Thanks,

UDHarold

Hmm,
I ran 12.90's at 105 with a 427 and a 5/16" line ,stock mechanical pump...

My question is,

How can 1/2" fuel line be necessary when the orfices in the carb (needle and seat are usually no larger than .135"

Say you are running a Holley with 2 needle and seats.
The area of the 2 open seats (not figuring needle interference), combined would be .0286"
Figuring an outside diameter of .375" with an tubing thickness of .050 leave the inside diamter at .275"
Area of .275 is .05936"
So were still 48% more area figuring a worst case scenario.

So why is .500" fuel line necessary?

I understand a need for an adequate fuel pump for the volume necessary to keep a 3/8" line fed, but I do not understand the need for any larger orifice than what the smallest orifice in the system is....


So explain in mathematical terms WHY a larger fuel line is necessary?

Originally posted by UDHarold:
RapidRobert,

I don't miind answering this question, as I have repeated it every working day for 23 years.
1st, NO ONE has ever told me they have SLOWED DOWN when they increased the volume of the fuel system the way I told them to. And I've never made a cent off of selling them 'trick fuel systems'.....
Thanks,

UDHarold I've been following this thread and wonder why no one has asked the obvious: Say you get a 1/2" line, you can't get a 1/2" or even a 3/8" needle and seat. Isn't that needle and seat going to be the biggest restriction anyway, or is it the filter? (I'm talking Quadrajet especially, although it seems to me Holley would be the same.)

If the filter is your biggest restriction, why couldn't you just get a 1/2" inlet/outlet filter and keep your 3/8" line?

No disrespect here, but maybe the reason these peoples times improved with a 1/2" line is because while changing the line they also installed a larger filter?

Mike

Thanks Harold

My best guess would be that the line works as a fuel log, storing the extra gas until the split second that its needed. My dad and I have had this conversation and many others like it the last few years and he now sees that this is not the 60's and things change, he was stuck on the speed of BB cars with 3/8 and 5/16(mopar) lines. He now runs a solid cam that stays set, a "little" 3.90 gear and a Holley DP and runs faster and more consistent than he ever has. Like I said earlier, my car went faster and its a 355 with a .480 lift hyd. cam. BTW, I run that Fram chrome and orange filter, its a cheapy.

Interesting thread going on here! I am by no means trying to dis anyone, and I have learned alot and am still learning. I have always been a proponent of maximizing stock components. I have been using a stock GM truck fuel pump :confused: on my Chevelle.
If we use the formula for CFM to size the carbs we use, can we then calculate the Fuel volume needed from that equation. then conclude the delivery required. A stock pump test procedure for volume is what? a pint or so in 30 seconds of cranking? Am I running my bowls low on the big end I guess I might be? :confused:

At one time I didn`t beleive that an electric pump was worth anything. They were noisy too!

I was then convinced to try a holley blue pump instead of my 110 mech. carter (I was running the stock 3/8 lines).

With the 284XE it picked up 3 mph!

Just thought I would share my experience.

Tony, thanks for the e-mail. smile.gif

I'm thinking along the lines of Unclepennybags. Not disputing anything or anybody, just trying to understand why. My Nova runs 91 MPH in the 1/8 and 113 in the 1/4 with the original 5/16" line all the way from the tank to the stock mechanical fuel pump. The gas tank has never been dropped on this car.

I might just rig a Blue back there to check it out. Of course, I'm running through 3 needles and seats , so it shouldn't be overkill.

BTW, I noticed a slight decrease of steady 3000 rpm cruise rpm from around 15.9 to around 15.1 switching from another cam to Harolds, which also gained me 7-8 MPH in the 1/8th.

The MPG issue may have to do with going from 114 lsa to 110. To many variables to conclude anything.

I'm looking at this from an engineering point of view. Say you have a 750 cfm carb and you are using all of it. For the sake of argument let's assume you are running at 12:1 air/fuel ratio. That means that you are using 51.7 lbs. of air and 4.3 lbs. of fuel per minute. Anyone know how many lbs. of fuel per minute a 3/8" line will flow at 7 psi?

Mike

Hom much does a gallon of fuel weigh? 10-20 pounds a stock pump can pull one pint in 30 seconds
Milan

AFAIK gasoline weighs ~6lbls/gallon.

So according to this data would it be presumptuous to as that a stock pump covers the spread with 50% to spare?

I have revised my fuel system to run on my Carter 172 on the street and then use a Mallory Comp 250 at the strip.

Just the turn of 2 ball valves and a toggle switch and I can run on one or the other.

Testing will commence in the Spring...... :(

I have used nothing but my Carter and -10 line up to this point.

FWIW here are my thoughts on the fuel line issue ...I support the you can't have a fuel line too big, camp ..... IMO it is all about short term demand, yes the carter pump can give you 172 gph and that is OK with 3/8 line but there are millisecounds when the inlet opens on a high HP motor and this pump needs and can pump 500gph and when that happens you need the volume to be available ......
Winston cup cars run AN 12 line with a mechanical pushrod actuated pump ...... and I do beleive Chev 4x4 454 carbureted trucks from the 80's had 1/2 " fuel line from factory !!

For my street/ strip car with AN 10 line and Carter 172 pump if I ran into fuel delivery problems before I would go to a electric pump you can buy an Uprgade Kit for that carter 172 that increases output even more IMO as long as you not adding Nitrous etc this pump should handle up to 600hp easily if the fuel line and fittings are sized right


In a previous project I found the Holley Blue pump rated at 140gph was only putting out 90gph at 9psi !!! , so IMHO like most things it's all about your engine combination and needs whether you need mechanical and electric but regardless you need the volume availble when the pump asks for it . FWIW

At 48 F (508 A) a cubic foot of normal pressure sea level air weighs approximately 1.25 ounces.

750 CFM (1.25) = 937.5 ounces/min
For a 10 second run -
937.5/6 = 156.25 ounces or 9.76 pounds

12:1 AFR = .82 pounds of gasoline or 17.5 ounces.

Looks like, theoretically at least, a pint (of gas, that is graemlins/beers.gif ) is about all it takes to get you down the track. :eek:

1 pint-Wich is exactly how much a NHRA Pro Stock Bike gas tank holds.Go figure....

...but the fuel level in the fuel bowls must be maintained at a constant level (i.e., it cannot drop at all) for the jets to supply enough fuel, so that pint of fuel must be sucked through the needle & seat in 12 seconds, right? (or 11 seconds, or 13 seconds, or whatever your car runs). It's not like you can say you start out with a pint in the bowls, so you don't need a pump at all...the float level must not drop during the run.

Go to your kitchen sink and see how long it takes to fill a one-pint container with the spigot at full blast...it takes a few seconds.

All of my knowledge on this is based on Water Flow in the Fire Service, so please bear with me because all of my values are based on Gallons Per Minute and Fire Hoses that are 100's of feet long. But the theroy is the same.

Fluid flow through a pipe, hose, or conduit is subject to friction loss over the length of the pipe. FL is calculated by FL=C(Q*Q)L

FL=Frictin Loss
C=Friction Loss Coefficient
Q=Flow Rate
L=Length of hose

So any time the diameter of the pipe is reduced OR the length is increased the amount of firiction loss is increased. For fire hose the value for Q is:
1 3/4" hose = 15.5
2 1/2" hose = 2
3" hose = 0.8
4" hose = 0.2
5" hose = 0.1

So as you can see the diameter of the pipe greatly affects how much friction loss occurs.

So if you want to flow 250 GPM through a 200' hose you will see the following Firiction Loss Values:
1 3/4" = 190psi
2 1/2" = 24psi
3" = 10psi
4" or 5"=0psi

So what I am trying to say with all of the junk is that there is allot more to it than my needle and seat are this big and my fuel line is larger than that so I sould be ok. The longer and the more bends that are in the fuel line than the greater the chances are that you will not get the flow that is needed.

Also, Mike you mention that the largest restriction will be the 3/8" inlet. And you suggested that 1/2" inlets with a 3/8" line might be a better idea. Well the oppsite is true. A 3/8" inlet is a restriction however it is a restriction that is say 1/4" long and so the FL will be very minor as compared to the FL over the length of the entire line which can add up to allot exspecially as demand increases. My example is we had 2 1/2" hose for many years. We wanted to increase to 3" hose but it was to difficult to change connections from 2 1/2" to 3". And so we purchased 3" hose with 2 1/2" connections. The results was a minor FL increase due to the momentary size reduction in the couplings, but the size increase of the hose made a much greater improvement. The resulting FL at 500GPM over 100' was:
2 1/2" = 50psi
3" with 2 1/2" couplings = 30psi
3" = 20psi

So all things being equal in the fuel system (line length, number and size of bends, number of connections, and pump size) every time you increase the diameter of the line you will increase the output significantly.

Sorry for the trip over to water and fire flows but that is where my major experience with fuild flow is from.

airrj - very well explained, thank you

Originally posted by airrj:
....So what I am trying to say with all of the junk is that there is allot more to it than my needle and seat are this big and my fuel line is larger than that so I sould be ok. The longer and the more bends that are in the fuel line than the greater the chances are that you will not get the flow that is needed. We'll get the fluid books out this weekend and give it a closer look. Remember though, we are talking about maybe 15 feet of line tops.

Originally posted by airrj:
...Also, Mike you mention that the largest restriction will be the 3/8" inlet. And you suggested that 1/2" inlets with a 3/8" line might be a better idea. Well the oppsite is true. A 3/8" inlet is a restriction however it is a restriction that is say 1/4" long and so the FL will be very minor as compared to the FL over the length of the entire line which can add up to allot exspecially as demand increases. Actually, I was floating the idea that the smaller FILTER with a 3/8" inlet might be the problem - not the size of the inlet per se. While I agree with the friction in the line increasing as the length of line increases, the shorter the line, the more likely that the filter is "check point Charley"

While your real life observations about fire hoses are no doubt valid, fuel lines are only maybe 12-15 feet long as opposed to a 200 foot long fire hose.

Mike

I have often wondered if the Carquest 3/8" fuel filter I use between the pump and carbs is adequate. How to know?

I've got my UD cam stabbed in the way Harold wanted it, +6, so the engine is subject to the demand issue he raises. Could the fact that I have three float bowls ( albeit the smaller side hungs ) compensate for the fuel line/stock AC pump? Guess I won't know until I rig an electric pusher in-line.

Some great info here. Never associated cam timing with fuel demand. I put mine in at 2 deg. retarded so it would make power (torque) in the upper range. Perhaps I inadvertantly covered an inadaquate fuel system. (Holley mech 130gph & 3/8" fuel line). Tony A. graemlins/clonk.gif

a friend of mine has a blown 67 vette with a tri-carbed 454. he runs 130 mph in the quarter. his fuel system is a stock tank with 3/8" fuel line and a carter 174 nascar pump. i believe he put out 675 foot #'s on a chassis dyno. mike

Originally posted by 427L88:
I have often wondered if the Carquest 3/8" fuel filter I use between the pump and carbs is adequate. How to know?

Be interesting if some one would run a A-B test to find out. Hint Hint!!! Don't get me wrong. I'm not knocking 1/2" lines, and while your car certainly turns some impressive times now, it may run faster with a 1/2" line.

Rather than go through the hassle of installing that 1/2" line though you might be well served to upgrade the filter first. Run it at the track, see if your times improve. If not, run the 1/2" line and see what you get.

We run 3/8" outside diameter steel braided lines. Approx 20 feet from the fuel supply to the engine. Far as I know, the pump puts out ~70psi. I can still get 60+ psi at the engine. I've run 460's and 415's for extended periods (hours) at 5,000 WOT and was able to deliver enough fuel to get 11.5:1 and could probably go richer than that! In this case I'm not sure where the filter is. I am sure though, that it isn't between the pump and engine.

Mike

Well there is a good point. Where should the filter go? Before or after the pump?

Wow, I never really thought about cam timing effecting the required fuel delivery before. My 383 is going super lean with a 60gph Holley mechanical pump and 3/8" line stem to stern. My dad's 383, same carb and similar sized cam but timed very differently has no problem on a stock AC mechanical fuel pump for a 77 GMC truck. I have a new pump on the way hopefully, and I am going to install it as soon as I get it. Then god willing I won't have anymore fuel supply issues.

THIS JUST IN: My new fuel pump arrived on my doorstep about 20 minutes ago. I am installing it tonight. I'll post changes in fuel pressure when I have the data.

A 3/8" inlet is a restriction however it is a restriction that is say 1/4" long and so the FL will be very minor I disagree with this statement. If you restrict the line at any point (however short the restriction) the flow is inhibited the same amount from that point on.

It would make very little sense to run a 1/2" line and have just one 3/8" fitting!

Also most of the 140 GPH and under pumps have 3/8 fittings simply because that is all that is needed.

If you're running alcohol and a Dominator, then you'll need 1/2 inch line and a 250 GPH pump.

Actually, if you're running alcohol, you'll need a 3/4"(#12) line---alcohol requires 2.2 times the volume of gas to make the same BHP. This is why so many injected alcohol cars run down-nozzles, to get all that alcohol out of the runners, where it is inteferring with airflow!

Looking at the flow-per-minute is only useful when you're running a minute at full-throttle.
Most of the cars with nice-sized cams are running between 6 to 12 seconds in the quarter.
A car with a T350 and a 4000 SS converter will run between 4000 to 7500 3 TIMES in 11 seconds, under a tremendous inertia load, forcing the fuel backwards. The only thing important is how much fuel the system will pump in those 11 seconds. The cam governs airflow, and the rate of airflow pulls the fuel out through the jets. BHP is governed by the air/fuel ratio, as well as by the volue of air/fuel present. If you have a lot of air, but not enough fuel, your system is lean, and flat on power. If you don't have as much air, but you have the proper air/ffuel ratio, your system will make power.
My comments about MY cams needing 1/2" lines are concerning MY cams only. Ask other companies about what type of fuel system they recommend, they are responsible for their own cams.
The most common complaint about UltraDyne cams were that they would go 'lazy' on the top-end, and every complaint that I heard, that actually listened and did things the way I suggested, told me that the 'laziness' went away, and PH and ET picked up.
If you'd like to prove me wrong, please buy one of MY cams and try it your way. If you're right, it'll run just fine with whatever fuel system you want to use. If it doeson't pull on the top-end, give me a call and I'll tell you how to make it work......

UDHarold

Originally posted by CDN SS:
FWIW here are my thoughts on the fuel line issue ...I support the you can't have a fuel line too big, camp .....That would be incorrect.

One thing you didn't consider is that the fuel isn't just free flowing to the pump or carb. When a vehicle launches, the fuel is being "held back" by the g-forces of that launch. The larger the fuel line, the more fuel weight is being pushed back to the tank/cell. This weight of the fuel then has to be overcome by pump pressure (rear mounted electric) or by pump vacuum (front mounted mechanical) which reduces the pumps ability to do it's job. Lower PSI street/strip pumps (6-12 psi) are more vulnerable to this than the real high pressure race pumps (some are 20-30+ psi).

Fuel pressure vs fuel volume vs line size is one of those endlessly debatable topics because there are so many people on both sides that *seem* to have good results with big or small size lines.

Marty was right that it is all about being able to meet instantaneous demand - volume wins hands down. Pressure only indicates backed up flow - it says NOTHING about how much actually made it out the other end. I run across this all the time whenever talking about the psi of boost in a supercharged engine application (air or fuel, pressure is pressure) - most people have a hard time understanding how it is possible to change a few select components in a supercharged engine, resulting in a lower manifold boost reading, yet power increased dramatically. Bottom line is that the throughput of flow in volume always trumps the measure of stacked up pressure.

I learned a lot about fuel volume while building my supercharged engine. The first dyno facility I used was convinced that I had run out of carburator capacity because the engine was going lean at ~ 25 to 26 fuel psi, 16.8 psi of manifold boost, and power in the very low 700 hp range. Not completely confident of the first facilities tune and setup (and not wanting to prematurely waste the $12,500+ that I had spent on the engine) I took my engine to another facility for a look-see and further tuning/setup. When the second shop told me my fuel pressure regulator was insufficient I protested that it was showing plenty of fuel pressure for the boost level. They went on to explain that it was a volume issue, not a pressure issue. The couple of hundred $$ that I spent on a new regulator of their choice was the best money I spent. With that and a couple of other small changes power shot way up into the mid 900's, boost psi up only slightly from 16.8 to 17.1, fuel pressure reading in the same 25 to 26 psi range - and a very nice BSFC that was considerably fatter than at the first shop. No carb problem here, but there was a fuel volume issue that the second shop uncovered.

Thomas

Todd makes a great point about G forces on the column of fuel. Again, I can see why a pump pushing the column rather than pulling on it would be superior.

Also, when I had a "nose over" problem at 7200-ish or so, I removed the regulator altogether as I suspected it might have some restriction issue. ( Holley regulator). Unfortuntely I also swapped out the stock push rod for a light Moroso one, so I can't tell which of the two things affected the clearing up of the "nose over". ( also surpised the carb handled the 8+ psi at idle.).

Don't know if that adds anything, but I understand its volume, not just pressure. And like a "mini" version of Thomas's experience, removal of the regulaotr seemed to allow more fuel volume.

The most common complaint about UltraDyne cams were that they would go 'lazy' on the top-end, and every complaint that I heard, that actually listened and did things the way I suggested, told me that the 'laziness' went away, and PH and ET picked up.
If you'd like to prove me wrong, please buy one of MY cams and try it your wayOk Harold, I would rather you prove me wrong. But this will be a good test. So here we go!

Below is my Time slip from yesterday, and current combo.

I was planning on doing a cam swap this off season to a custom grind of the CompC Solid Roller with .654/.660 lift .248/.254 @50 cut on a 107, installed straight up. Along with a head mill to bump compression to 11:1.

I will install 1/2" fuel line, new pump and filter as you suggest! Along with buying your grind, if you tell me by doing this I will see 2+ tenths lower ET. I already know the above cam change alone is worth at solid 10th!

Also the MPH already look's lazy on the top end but I just don't think it is fuel related.
http://home.swbell.net/kenladd/timeslip1.jpg
My current fuel system is a Mallory 110 with all AN fittings and 3/8 line.
70 Chevelle
3830 lbs. (with driver)
468 BBC
049 oval port heads, .030 mill & mild port work and 2.19/1.88 valves
10.25 to 1 SRP forged pistons (26cc dome)
Comp Cams Solid Roller XR280R (11-771-8)
242/248 and 646/653 @50
Dynomax headers/3" bullet mufflers
Turbo 400 (Street/Strip, Auto/valve)
ATI 8" 4400 Stall
4.10 gear 29.5x10.5 slicks

10secBu, BTW, the ATI converter you suggested was worth a 10th, very happy with it, Thanks!

FWIW I believe Harold's reasoning and experience on the subject, but it would have to apply to other brand cams as well. It has too . . . Harold's cams are great, but how can a simple cam BRAND cause an engine to require significantly more fuel when the car is only picking up a couple tenths and a few MPH (bast case - assuming similar grind specs, etc) from a cam swap?

If you do the calculations on how much fuel an engine consumes you might be suprised at how little the engine actually uses.

For example: according to the Holley Carburator Handbook by Mike Urich, a 400 cid engine at 6000 RPM consumes roughly 250 pounds per hour. If fuel weighs 6 lbs per gallon then the engine is only using 41 gph. A more radical 454 cid engine at 8000 RPM would use about 315 pounds or 52.5 gallons per hour - still WELL BELOW the free flow rating of just about any electric pump.

So if there is such a huge need to upgrade a fuel system to support a hot strip combo IMO it cannot be because the engine actually USES 280 gph. There's no way typical gasoline engines actually USE all that gas.

IMO what is happening is that the g's off the line combined with the bends in the line and friction make "overkill" necessary. The other very important factor is that most pumps are rated FREE FLOW rather than under pressure. I haven't seen pumps rated at the pressure we use them at . . . wish they would rate them all at 6psi.

Personally, my 3/8" line and Holley 110 gph mechanical pump work fine (using a Comp cam).

I have to say that this is one of the most thought provoking threads that I've read in quite some time.

Keep it up guys. graemlins/thumbsup.gif

Originally posted by Eric68:
For example: according to the Holley Carburator Handbook by Mike Urich, a 400 cid engine at 6000 RPM consumes roughly 250 pounds per hour. If fuel weighs 6 lbs per gallon then the engine is only using 41 gph. A more radical 454 cid engine at 8000 RPM would use about 315 pounds or 52.5 gallons per hour - still WELL BELOW the free flow rating of just about any electric pump.Were those engines on engine dynos or were they accelerating 4000 pound crates over 100 mph?

Tim.

Bingo, Tim has it. Do not confuse steady state fuel demands to the instantaneous demands of accelerating a heavy car to speed - quite different they are.

Thomas

Hopefully there will be not too many mistakes in this post, I've got 2 Nyquils and a Hot Toddy in me.....
When I became Comp Cams' designer in 1977, there was no one there who knew how to design cams. they had been partners in Cam Dynamics, but the designer kept Cam Dynamics, and they were running off onld Cam Dynamics masters. I came in during January 1977 and started designing UNSYMETRICAL cams. Oddly enough, they showed this fuel-starvation problem at high-RPM, and we had to increase fuel supply.
At UltraDyne ALL the cams were unsymetrical. The trick was to have a delayed opening-point, and a slower, gentler, closing point.
When we look at an intake cam's opening point, we see it is during the exhaust stroke on the engine. The piston is rising, and pushing out the old exhaust gases, and there is a positive back-pressure existing in the combustion chaamber before the intake valve opens. When the intake valve opens, we call this back-pressure REVERSION, and it will enter and bloock the intake runner. The amount of reversion depends upon When, ie degrees BTDC, the intake valve opens, among other things.
Opening the valve later DECREASES the amount of reversion enterinng the intake valve, and allows the intake to recover sooner/faster during the intake cycle. The earlier the intake valve starts flowing cleaan air, the higher the port velocity, and the better the cylinder gets filled.
Because we are flowing more, and cleaner air, it puts a higher demand upon the fuel system, and requires sufficient volume of fuel.
This is why changing the brand of cam can make a difference.
BTW, in 1957 engineers were able to 'prove' that Don Garlits could not possibly go as fast of 8.97 in the quather. He paid them no mind......
That's enough for me tonight.....

UDHarold

For what it is worth, my HP500 EFI (injected 502, 8.75:1, 655 ft.lbs/575 HP without the spray) consumes 65 gallons per hour at 5200 RPM (approximately steady state). These numbers are confirmed from a flowscan on the fuel line, the ECU with a scan tool, and personal experience.

I personally do not see why anyone would not increase the size of the fuel line if they intend to race their car (especially if their goal is 11 seconds or less). There is no downside to it, except to remove the stock line (which can be replaced) and experience has shown nothing but positive results. Just because someone can run fast with 3/8 line does not mean that it is a good thing. Cost does not have to be an issue - both Moroso and Russel offer 1/2 aluminum line at a fraction of the cost of braided and, if you are patient, you can bend it to look original.

Just my observations

UDHarold,

Don't get me wrong, I mean no disrespect.

I agree with there being no mechanical downside to running the 1/2" line. IF someone is building a car from the ground up to race, they should probably start out with the 1/2" system. I'm merely looking at this from the point of view of someone with a desire to keep his car as stock looking as possible.

Where do you draw the line on this 1/2" fuel line issue? While I'm sure the 454 guy with one of your company's big camshaft would require it, how about the guy with one of your company's middle of the road camshaft and a 283? 327?

Since this isn't merely a steady state fuel issue, can a certain 1/4 mile time be used as a yardstick in determining what size fuel line to use?

Appreciate the time you are taking on this issue!

Mike

Mike you answered your own question as soon as you specified a middle of the road camshaft on a 283 or 327.

I don't know if there is a 1/4 mile time that determines when a larger fuel line is called for - because there are too many variable car weight/engine combos to get certain 1/4 mile times.

The only yardstick that I have ever used is the raw horsepower level. For carburated engines I've always considered ~ 600 hp and beyond to call out for 1/2" line.

Thomas

If there is NO downside to running a bit larger fuel line....why wouldnt you just do it. Somone can brag all they want about having 3/8" line but why? its nothing to brag about. Its not any more expensive to put in 1/2" so i guess i dont get why anyone would want a smaller fuel line.

Originally posted by TronDD:
</font><blockquote>quote:</font><hr />Originally posted by Eric68:
For example: according to the Holley Carburator Handbook by Mike Urich, a 400 cid engine at 6000 RPM consumes roughly 250 pounds per hour. If fuel weighs 6 lbs per gallon then the engine is only using 41 gph. A more radical 454 cid engine at 8000 RPM would use about 315 pounds or 52.5 gallons per hour - still WELL BELOW the free flow rating of just about any electric pump.Were those engines on engine dynos or were they accelerating 4000 pound crates over 100 mph?

Tim. </font>[/QUOTE]Tim, the weight of the car has nothing to do with it as long as the engine is trully fully loaded, unless your 4,000 car magically requires an AF ratio that is significantly RICHER than a normally optimal 12.9:1. A free reving engine is throttled, so of course VE is much lower and the engine uses less gas.

Its fairly simple math when you think about it. Displacement, engine RPM and VE determine how much AIR an engine uses, correct? Then based on the amount of air required you can determine how much fuel is used if the ratio remains 12.9:1.

Adivaman's real world data seems to support the idea that our engines don't use nearly as much fuel as we think. I still believe the overkill is only necessary to overcome g's during acceleration and resistance to flow in the fuel line NOT because an engine magically requires more fuel with a particular cam.

As I stated before, I'm not doubting Harold's experience or recommendation, just exploring the theory behind it.

Given a drag car with the carburetor situated approximately 15 horizontal feet from the fuel tank. The pressure observed in the fuel line at the tank, due to the G-forces of a 1-G launch is approximately 5 psi. What this means is that a rear-mounted electric pump would need to overcome 5 psi just to move fuel through the line. At a 1.5 G launch, this requirement increases to 7.5 psi. This is why a 6 psi pump is not enough and serious racers typically employ pumps capable of 15+ psi with a regulator mounted as near the carburetor as possible.

An engine driven mechanical pump would need to overcome 5-7.5 psi of negative pressure before fuel will move. This is probably approaching the vapor pressure of fuel, which means the suction created by the mechanical pump is momentarily vaporizing the fuel in the fuel line instead of transferring the fuel to the carb.

And just because the fuel pump is momentarily vaporizing fuel at launch, or not providing enough fuel at the top end does not meen that either of these conditions will be noticable at the track. Under both scenarios, the pump will not provide enough fuel to keep the fuel bowls full. As they begin to empty, the engine leans out, makes less power, pulls less air, and subsequently less fuel. The level in the fuel bowls continues to lower along with power output until steady state is reached, which means the inadequate fuel supply is exactly meeting reduced engine output.

I guess I shouldn't have enabled the e-mail notification. Got more than I asked for. This perhaps could explain the stumble the carb has coming off the line. With 60' times in the 1.65 range, I'd say it's time for some fuel supply upgrades. With changes over the winter months, I'll post results in the spring. All the input and experience we have/share here is invaluable. Tony A. graemlins/beers.gif

Originally posted by Eric68:
Tim, the weight of the car has nothing to do with it as long as the engine is trully fully loaded, unless your 4,000 car magically requires an AF ratio that is significantly RICHER than a normally optimal 12.9:1. A free reving engine is throttled, so of course VE is much lower and the engine uses less gas.Right. My concern was if the tests reflected the same kind of load on the motor as would be felt acccelerating a vehicle. Air/fuel ratio would be the same, but more work = more fuel. Also maintaining a constant speed reguires more work at higher speeds and acceleration requires even more work than maintaining speed.

Tim.

Does anyone have any theories why injected alcohol sprint cars show the same leaning-out, flat power curve when using my cams, and why they respond so well to richening-up fuel delivery on the top-end?
Some of you, by your posts, seem to think that all cams are alike, and only those posted numbers make any difference between them.
My program allows me to design 15.5X10 to the 14th different cams of the same lift and duration.
Most of these are so close together that we couldn't tell them apart, some of them are so soft and mellow that no one would want to run them, and some are so radical that they can't physically be made. But then there's a WHOLE BUNCH of them that work, more or less usuable. And this is before we get into unsymetric off-sets.
A number of years ago at UltraDyne I designed 8 additional 288R lobes. They were all 288 at .020, and .626 lift with a 1.5 rocker, but they opened and closed the valve at different rates, and had different off-sets. At .200 they differed by 3 or 4 degrees, and the valve timing diagrams were different. My question to the salesmen was, "Seeing how many races and National championships the original 288R has won, which of these designs do you think would be better?". Of course no one knew the answer, yet all of them had in excess of 10 years each as a cam salesman/technician.
Competition Cams spends over a million dollars a year to convince everyone that their cams are better than other cam companies. If all cams with 268° at .006", 218° at .050", and .454" valve lift were the same, their expenditures would be wasted.
Several cam companies have copied some of my cam designs, I have never copied anyone else's. Anyone who knows me knows that I believe what I say. I've spent the last 26 years designing nothing but unsymetrical cams, and I am convinced of their superiority in airflow over the symetrical cam. I will continue to try to improve over my old designs......

UDHarold

UDHarold, you don't have to defend yourself b/c YOU HAVE DONE IT!!!

BTW, I haven't read every word but an analogy please!!

Totally off the subject...

Once, when I was installing refractory gunning plastic, I ALWAYS specified that a TRUE 2" diameter air pressure delivery system had to be ran to the gunning machine!! I'm talking a 750cfm portable air compressor running 125 psi of air to the gun!!

The was an old hard-headed owner that I think the world of that my boss and I were helping get into the plastic gunning installation business..

He and his crew were having fits b/c the old man HATED 2" diameter Boss coupled bull-hose b/c the 50 foot sections are heavy as h-ll to pack around!! He didn't even own any hoses like the 2" STUFF..

Anyway, he had piped the gunning machine to (2), 1.5" diameter hoses AND the SOB still wouldn't gun the plastic!!

He got right up in my face with my boss on my left side and demanded to know why the stuff wouldn't shoot!! He was pissed off to say the least!!!

I told him to unhook the (2) smaller hoses AND run a true 2" air line and he said that (2), 1.5" air hoses had more flow volume then (1), 2" hose!!

I looked over at my boss, threw up my hands and said, boss tell him again and walked off!!

Anyway the old hardheaded guy installed a third, 1.5" airhose to the gun AND then the SOB started shooting right!!!!

WHAT I am getting at here is that you HAVE TO TAKE IN ACCOUNT QUALITY of a fluid's flow be it air, water or gasoline!!!

AND it just so happened that in the case of gunning plastic the magic setup was a true 2" diameter air hose, a 750 cfm air compressor running at 125psi!!!

I figure the same here with a bigger gas line piped into the system b/c when a big engine gets ta sucking, like Harold say's, it will need more fuel up top which the larger 1/2" line will give!!!

'nough said..

pdq67

PS., the material hose was just 1.375" diameter AND let me tell you it was like holding onto a fire-hose!! I felt like I had been beat to within an inch of my life after installing (20)3,000 pound skids of the stuff in an 8 or 10 hour day... I kinda just wanted ta fall right over after the gunning machine was shut off......

Harold and others,

I'm sure you make a good cam, and I also believe an unsymmetrical cam will make more power,

However a given motor that makes X HP at XXXX rpm will consume a set amount of fuel at a set air fuel ratio. PERIOD.
No matter who's cam it has or whatever.
It takes a certain amount of fuel to make a certain amount of power.

Now it may very well be true that some of these hard hitters using a big cam, big cubes, etc.. need a better fuel delivery system I feel it has NOTHING to do with cam company but only HP produced.

Nothing wrong with 1/2" line, but a 3/8 line with an adequate fuel delivery pump may work fine, as some have proven..

Jacob,

You are absolutely correct....
At any fixed RPM, all cams making the same BHP should use the same fuel.
Unfortunately, most race cars, except for things like Bonneville Streamliners,ACCELERATE through the RPM band, sometimes over 1000 RPM/second, and 2,3, or 4 times in a 1/4 drag strip. We even see the same thing in oval tracks. The SB288/296H8 requires 1/2" line, even when running a 500 cfm 2 barrel. Hundreds of racers have reported gains up to .1 sec per lap on 1/4 mile ovals when they replaced their old 3/8" line with 1/2" line when using this hydraulic cam. My solids and rollers just make the problem worse.
I claim that my cams make more torque. It requires more fuel to make more torque, and the cam is flowing more air at each RPM as the engine accelerates, more fuel is being pulled out through the jets. Perhaps my cams change RPM faster. Whatever it is, if the fuel system is inadequate to deliver enough fuel, the engine goes lean and flat somewhere past peak torque, and before what would be peak horsepower. If the engine is turned off during the flat and lazy phase, the plugs will show a lean condition. If you drive it back to the pits, the plugs will read normal.
What I am saying has worked for 23 years.......
And I am not saying it is necessary for Brand X cams, let them tell you what their cams need.

UDHarold

UDHarold,

Is there a rule of thumb you can use when considering what size line to use? If not, are you saying that any one of your cams in any size engine will require the 1/2" fuel line?

Appreciate the time you are taking on this issue!

Mike

Harold, I certainly am not implying that all cams with the same .050 duration, lift, LSA numbers, etc. are the same. I'm not that naive. The camshaft efficieny will certainly affect the engine's VE and consequently change the fuel requirements.

My point is that if you flat out make the best 288* cam in the world how much higher can your cams VE be than the next best 288* cam? 5% maybe? I think most people go after a cam swap because they aren't happy with the cam they have right? So if they suddenly get the right cam, and a darn good one at that, certainly their VE goes up and fuel requirements would go up proportionally.

The Sprint car having a flat power curve due to a cam swap would be no different from a 1/4 mile car. Sprint cars see G forces and resistance in their fuel lines too, probably even more-so than a 1/4 mile car. The G forces would just be in multiple drections. Same principle.

and on another note. If one decides they want to purchase one of your cams what is the best way to go about it? What about a cam recommendation?

Mike,
My smaller cams, the ones considered daily drivers, do not require anything but stock fuel lines. Cams like the BB276H12, or the BB276/286H12, are happy with stock fuel lines. In STOCK engines, the 276H12 makes about 380 BHP without headers, and works with a stock fuel system. The BB288/296H10 runs out of gas by 5000 with a stock fuel system, in 330 HP 454 jet boats, it will not rev above 4200 UNTIL the fuel system is changed. Then it goes 5500.....
If you are using one of my cams and the engine goes flat and lazy at some high RPM, this is caused be fuel starvation. If the engine pulls hard as high as you want it to, you have no problem. It's that simple.

Eric,
give me a call next week at Lunati, 901-3655-0950, ext 135. I am under the weather will a bad cold this week and do not know when I will be in... Or you can E-Mail me at home, brookshire@panola.com .

UDHarold

Harold, does this have anything to do with the old idea of an engine being able to pull more cfm than its carb is rated for at peak rpm causing a lean spot? I have not read anything on this in a long time and what I did read was from the 70's. This was cured by going bigger on carb causing a loss on the low end. Could a bigger fuel line have fixed it?

I can vouch that cams with same specifications will not perform the same. In 1985 my father built a flat top 350 with factory open chamber heads, cast iron intake, quadrajet, cast iron ext. manifolds for his '70 chev 4x4. It was 8.8:1 and ran a Comp Cams 268H. Note this early of a cam may have been one of Harold's designs.

Anyway the truck had a 4 spd trans, 33x12.50-16.5 tires and 4.10 gears. Mash it to the floor at 3,500 rpm in second gear and it would flatout roast the tires and chirp into third if you could shift fast enough.

We discovered some lifters were not rotating and got talked into running a 262 Isky. It could not touch the performance of the comp.

After wearing that engine out, we rebuild it and installed a "Brand-X" cam with the same advertised, 0.050, lift, separation, centerline, etc. as the original Comp. It never ran the same as that original motor.

Thanks for the insight Harold. Sounds like you will be able to tell when you need 1/2" line.

I had gotten the impression that some of the folks had been running 3/8" line with one of your cams and been happy with it until they switched to 1/2"

Regards,
Mike

Just wanted to drop in and say [B] THANKS {\B] to Harold for yet another informative post. Nice to get the logic behind the reason, and the anti-reversion makes a lot of sense! My cousin is running several Ultradyne cams, and he also received performance gains by upgrading his fuel system.
Hope you're feeling better Harold graemlins/thumbsup.gif

How can a 1/2 flow more when Needles are so small?

so what I get from this is that fuel flow need is never a constant. What we need to build a fuel system for is max potential flow. Even though it may be many times more than a calculatable value.
Things like intake reversion(Variying valve opening rates), momentary fuel line inertia load, overall system routing(BENDS and Kinks). even though the line may be reduced by the size of a restriction(JET,Needle /seat) there needs to be a sufficient POTENTIAL(adequate pressure and volume)to overcome the MOMENTARY point(s) of restriction.

Kinda like tuning intake runner size?

Milan

Now is a 1/2 line needed for your small solid cams?Like the 230-238@.050 range ones, in a 350?

Milan ...... that's how I understand it and how my circle track engine builder explained it to me

ALL Go .... go thru this post you will see your answer

That makes sense to me. I am not a doubting Thomas! I have always had the need to understand thats all. I was of the opinion "who in their right mind thinks they need these mega volume per hour pumps?" I've said it before and it bears repeating. The more I learn the less I know!
Milan

UDHarold,

Reading all these postings and your responses makes we optimistic that one of your cams would be just what my Roller 408 BBC needs to get a little more torque/HP across the power band (3500 - 7500+) and would also work nicely if I was spraying my fogger at 200+ HP...

You should have a detailed email of my motor/car combo that I sent late last week under username rhexemer63@aol.com. When you have a chance could you give me your recommendations? I'd be glad to bring this discussion to this forum if you'd prefer so we can all benefit from your advice. Whatever you prefer.

Thanks! And I hope you feel better soon.

Rich

Guys (and UDHarold),

Just bringing this back up to the first page in hopes that Harold will see it and help me out with a new roller cam selection....

BTW.... With the last transformation of my chevelle, (and this wasn't the 1st since I've had it since I was 16 and now I'm 40) :eek:

I though ahead and used AN-10 lines with a Holley Volumax 250 gal/hr pump and one of their large port regulators to make sure my motor had an adequate fuel supply from both the carb and for the NOS fogger system. I also made sure that all the fittings were as big as possible and actually drilled a few out to avoid any restritions that could decrease fuel flow.... Also made sure to pick filter(s) that were large enough to minimize any flow losses.... I'm an engineer and tend to consider all these things and often "over-engineer" the solutions, but to each his own and it does keep me off the streets at night... LOL

Rich