OK - I went to the track Saturday with the new CAM, 1/2 fuel system and slicks. The car ran good but not to my expectations. I got a dead hook and the best 60' time ever. 1.82. I was getting 1.97 to 2.01 with my street tires.

I went to Bradenton just before Hurricane Jeanne arrived so it was a little humid but not real hot. It was pretty empty and I got to make 5 runs before 1pm. I had to leave at that point because it looked like the weather was deteriorating.

I was happy with the way the car hooked but not with the way it ran. It ran equal to my best time with the old hydraulic CAM (Performer RPM) and street tires on my first run. I expected more. I jetted up to see if I could get more out of it after the second pass. It got worse. I have two big issues that I can figure but want to hear more ideas.

First, I think with the addition of the better LunatiDyne solid (276/284)CAM I should have made more power. It is either the heads or the carb or both limiting my power making ability. Probably the heads more than the carb. I didn't go to the bigger valves when I had the 781's done. Is it worth taking them back off and having the bigger valves installed?

Secondly, I should have been able to get more out of the 60'. I was not spinning, it launched straight and never moved around or shook. My theory - converter is a POS. I need a good 10" 3500 stall to get this number down. I don't want to spend a fortune but what do you suggest?

Let me hear your questions and thoughts.

Troy.

Post your timeslip please

I'll have to do that tomorrow. I don't have it with me. I did run 12.74 @ 107.6 with a 1.82 60'. My 1/8 mph was 87.? and I thnk the 1/8th Et was about an 8.4 something. What else do you want to know?

Troy.

Your 107 MPH indicates a 12.30-12.45,maybe even quicker
Concentrate on your 60 ft.
What convertor are you running now?
Is this the same cam as Gene's ?

I believe it is the same exact CAM that Gene runs.

The converter is a hughes 2500 stall that actually stalls around 2800 in this car. At least it used to. I'm having a hard time power breaking past 2000 now. I don't have power brakes but I do have a good set of manual disks on the front. The converter has to go.

What's your opinion on the heads/valves? Is it going to make sense to put the bigger ones in? I can't afford new heads right now.

Troy.

Troy,I think your 107 MPH is good indicator your heads are fine.You need more convertor/better 60 ft.

But why would my MPH be worse than the best run with the old Performer RPM hydraulic cam? Shouldn't the newer design of the solid cam have made me more power and increased my MPH.

I know the 60' has to improve to get my ET down.

Slap me if I'm missing something obvious. I just can't figure this out.

Troy.

You installed it advanced as per Harold's recommendation? ( I think that might be less of an issue with your better heads, but?) ?

Hmmmm, maybe Chris can help with this, unless our cars are dramatically different in weight, I would have expected a higher mph with the swap. Quite a bit higher actually. I've havent raced it in a bit, but in the 440ci, the 67 will run anywhere from 116 to 118 mph depending on me and air. Even if the 70 is slightly heavier than the 67, you have 30 cubes , and I'd deduct some for the tranny vs a manual...so..... ?????

Sure your converter/tranny isn't toasted? Have you done a compression check on the new assembly yet? Maybe something isnt sealing?

Or maybe for some reason that cam will run a Chevelle to 118mph with rect ports and only 107 with ovals?

KIDDING!

Even thought he big valves would have really helped with the .580+ lift of that cam, I still would have expected a MARKED improvement over the old grind, especially in mph at first.

I'm not experienced enough with that cam in 454s to know what they'll run.

I think the converter is toasted in my opinion. It's stalling lower than it should.

I haven't done a compression check but perhaps I need to.

The CAM is installed 7º advanced as Harold recommended. I have played with the timing and jetting and still no improvement. Is it possible I need a bigger carb to get the Air/Fuel into the system?

I think you may have mis-understood about the valves. I did NOT install the larger valves and I'm wondering if that was a big mistake.

Troy.

Gene,your car with a TH400 and factoring in 10% convertor slippage would probably yield a MPH about 112-114 I would guess.
Troy,what carb are you running?

I'm running the Holley 4160 750CFM with vacuum secondaries. I would like to try something like an 850 DP. That should confirm whether the top end problem is my heads or not.

Troy.

Before you do anything get your convertor issue settled. A dieing convertor will kill MPH as well as ET. You can make all kinds of changes but if the convertor is sick you are just wasteing your time.

Troy, no I understood about the valves.

Converter and fuel system. That cam is going to be ramming alot more charge into the cylinder than the old one. Even if you never noticed a deficit before, you might now.

Set your floats a bit on the high side and make a pass and see if anything changes. What kind of fuel pump are you using?

"Don't know 'nuthin' about no converters" except to know that a bad one, as an auto tranny, can be a huge parasitic drag on things.

10-4 Mike - that makes sense. I will see about getting a replacement. What would you suggest? I don't really want to spend anymore than $300-$400.

Can I really put a 3500 stall 10" in there and still cruise at 3200 RPM without getting the tranny overheated and wasting gas? (I know I shouldn't be worrying about wasting gas and running low 12's or 11's in the same car)

Troy.

Not the heads IMHO. My combo with stock 049's made 490 HP, 500+ torque on the engine dyno.

I'd take it like this before you go out and spend any more money.

CVICIC

That is:

1. Compression test. Verify that everything is sealing right. What are all the cylinders running?

2. Valves. What's your lash? Did they need resetting after your day at the track? Are they "seated in" real good yet?

3. Ignition. What's your timing curve? As in, how much initial and mechanical? Your vacuum advance shouldn't be a factor at the track when you hit WOT, but I always disconnect and plug mine to eliminate any variable.

4. Carburetor. Are your floats set correctly? Especially the secondary float? Are your secondaries themselves opening? What color secondary spring are you using? What size squirter? What is your jetting? What size power valve?

5. Ignition. After your initial check of the timing curve, I'd see if you can move it around a bit.

I just test drove a friend's '68 Camaro the other day. 406cid, GM Fastburn heads, GM aluminum dual-plane, 700R-4, 3.73's, Crane cam (can't remember specs, but it wasn't ideal, yet better than stock)...yadayadayada. The absolutely laziest car I've ever been in. graemlins/sad.gif It would baaaarely scratch the tires and had NO giddyup and go. Turns out he's running 4* initial on timing. We didn't have time to mess with it any more, but I've got some digging to do, to find out why he can't run more than that. He had tried and the car wouldn't run at all. Anyway, timing can make a HUGE difference in performance.

6. Carburetor...again. After you've reset the timing or at least tried something a little bit different, retune the carb to match it.


All this stuff is pretty much free. Or if you don't have a compression gauge, jets, secondary springs, etc....then it might set you back a few bucks. However, it's cheaper than a new converter (that you definitely might need anyway) and it could verify any other problems instead of throwing money at it.

Good luck and keep us posted. You may need to spend some money, but I hope you don't. I'd like to see you pick up some E.T. off of what you've already worked so hard on.

I'd give it another try in better weather conditions. With humid air and an approaching hurricane you had some of the worst conditions possible for making power. Humidity is a big power reducer because it displaces oxygen in the air and hurricanes are accompanied by very low barometric pressure which is another big power killer. The higher the barometer, the more air fills a cylinder on the intake stroke.

ak - Perhaps but those are closed chamber heads aren't they? How do you like that converter you are running? What did it run you if you don't mind saying?

Justin - That's some good information. I have varied the timing the last time to Sunshine and found that 36 total is where she likes to be. It's all in by about 2800. The carb is opening ATW and I have played with the jets but not the pump or squirters. I don't get a bog so I'm guessing the pump is sufficient. What do the squirters affect? Isn't that rated to initial response as well? It's been a while since I've checked the floats so i will double check them and look at the compression numbers as well. A leak down would probably be nice to do but I don't have a tester - I will see if I can borrow one. I will also have a look at my lash again. (Gene where do you run yours?)

Von - the weather crossed my mind but do you think it would have made 2-3 tenths difference in a car like mine? If so perhaps I don't feel as bad. I will check some of this stuff tonight and get back with some info for more pondering.

Troy.

Yes it can make as much as a good 2 tenths difference. BTDT. Maybe more in the case of a super low barometric pressure. Also headwinds, tailwinds, etc. I'm assuming your running at the same track. There can be big differences in tracks too. You were probably hooking better due to power being down and/or cool temps with no sun making traction better.

I run an ATI 10" 3500 stall converter with 3.73's,no problems with trans over heating,I also have a Derale deep pan,and an external cooler. Personally I think you need the 2.19/1.88 valves as a minimum in a BBC if you plan on any time at the track.

I run the lash at .019 cold or .023" hot. ( or tighter, with rect ports on a 439, it does it's best work @ 4500+) But that's a 'tweak' thing, it's not worth 2-3 mph , could it be?

Troy, my motor combo is the same as yours with the exception of the bigger 2.19/1.88 valves, one step smaller 272/282 Lunati cam and a 850DP. My 65 mph's in the 114+ range at about 3500# total weight (your pushing probably another 400#). I would doubt that your making any less hp than I am so what would be the mph penalty for 400#'s ? Maybe someone can chime in with and factor for mph vs weight.

As far as the converter goes I'm running a tight 10" BTE (about 3000 stall) with a 3.08 gear. No problems so far with heating of the oil. I will say that this converter works like no other I've had, doesn't even hardly act like a stall converter under normal driving but just jump on it and its there!

Jeff65SS
Best 1/4 mi 12.57
best 1/4 mph 114

Are you sure the fuel pump is giving you enough fuel at the top end of the track?

Jim

Sorry for being late on this post, but here's my thoughts.

Your 8.4 half track time should be lower with the 87 MPH and that 1.82 sixty foot. What RPM do you shift 1-2 at? If your TH400 is already slipping, then a higher RPM solid won't help it out any. i.e. power made, but not used.

What are your RPM through the traps? If you shift 2-3 at the 1/8th (like I do), it's a good indicator to use that MPH and and compare it with your shift RPM. but be honest, or buy a play-back tack. ;)

I think the new converter is a good idea (assuming you haven't tinked with the spark curve or total timing). I spent $800 on mine... but my hydraulic 402 motor runs the same times your combo does. smile.gif It's a crucial part to say the least.

Side note: are those slicks on lighter or heavier rims? Rotational mass will affect top end MPH.

Troy, If you got pretty good traction and only got a 1.82 - 60' it would seem your down on power. Who did the work on your heads? Sometimes porting without the use of a flow bench to quantify your results can result in lost power instead of a gain. It also seems that advancing the cam by 7 degrees is quite a lot. Most of UD Harolds cams are ground advanced to start with. A faulty converter or a fuel problem might also be a possiblity. Those things just have to be changed one at a time to check them. Pick a day without an impending Hurricane in it and try again before you change anything and see if anyone has a weather station so you can eliminate the weather as a cause for your lack of power .

Call The Converter Shop. I've heard a lot of great things about these folks, though I haven't used them yet myself. He should be able to get you set up at a good price.

http://www.tcsperformance.com/ppdnew/performanceconverters.html

Harold, fwiw, I have the same grind indexed to a 103 ICL and it flat out rips. ( part of the "over" advancing was to keep inlet velocity high for the lil 440 through big ports and 1125 cfm of carbs.)

Unless it sets up completely differenct waves with small inlet ports, I can't see it holding it back.

You're going to find something amiss, you should be making more power. By my ROUGH reckoning 115-116 mph worth of power.

Thanks for all the replies guys.

The heads were ported by me. I didn't get real drastic. I simply took the burrs out of the bowls and smoothed the short side radius and gasket matched the ports.

The wheels are Corvette rally's just like my street tires. The slicks are a little taller than my street tires. They are 28" tall and the street tires are about 26.5" tall.

I looked at the slip last night and the 1/8mph was actually 85 not 87mph. Everything else I stated was very close.

I am going through the traps at about 5600 or 5700. The 1-2 shift is about 5600. I did make one run shifting manually and I hit the rev limiter at 6000 on the 1-2 shift and the run was a 13.1 at 105.

The fuel pump is a Carter 172 race pump with 1/2" fuel lines from the tank to the carb. plugs looked about right .. maybe a tad rich.

I ran a compression check last night and came up with 195-200# on all cylinders. That made me feel a little better.

The cam is installed at 7º per Harold's instructions. That includes the advance ground in which, if I remember right was 4º.

The more I think about it, I know I need to change the converter. I would like to try a larger carb... say an 850 or so and see what that does and then look at the bigger valves. I'll see if I can borrow a carb to test before buying anything. The only thing I know I'm going to purchase is a converter. Jeff, how much was the BTE? I don't want to spend $800 like Mike if I can avoid it.

Gene, I'm lashed at .024 cold. I haven't checked them hot. I will try going to .019 cold and see if that wakes it up any.

Troy

Converter sounds like its junk to me. My car crossed the line at 6000 at 118mph. 4.10 gears and 27in slicks. If your crossing at 5600 you have a lot of slip in the trans or converter.

Troy, I think I paid about $375 for the converter through Steve Oldani here in Iowa. Heres a link to his webpage:
http://oldanimotorsports.20megsfree.com/index.html
Give him a call, very helpful.

Jeff65SS

Troy,
For info, 107 with no slippage, 3.73's & 28" tires is about 4800.
At 5600 you have a wee bit of slippage :D

I am not a convertor guy but I think 15% is a little "excessive" :(

And weather can make a HUGE difference,, call the nearest airport & ask them what the baro & humidity was on the day in question just for giggles ;)