10/24 Track results...

69-CHVL · Oct 25, 2008

Went to Cecil tonight, Joe let me borrow his M/T DR's to use instead of my ET streets (same size). Much nicer to drive on I must say. Got there at 6pm, made 4 runs, left at 6:51 :thumbsup:

I would be lying if I said I was happy. But hey, 4 runs and nothing broke, so I did have a good time
.
1)2.08-8.24/90.37/12.62/113.94
2)2.02-8.31/88.85/12.80/113.35
3)1.92-8.11/88.50/12.49/114.38
4)1.87-8.04/88.33/12.43/113.84

I was having a hard time hooking and leaving. Once I dropped the tire pressure from 18 to 16 I got the 1.8.

But I think I found my problem, which surfaced its ugly head last time I was at the track...fuel system (I think).

While I was flying down the track, I kept my eye on the AFR meter as I went through the traps. It was at 14.0 exactly on the 3 runs that I looked at it! I am running a Prosystems 780 right now. Last carb I had was a Holley 950HP, which pretty much ran the same AFR through the traps. Around town, I'll do a 3rd gear blast and the AFR hovers around 12.8-13, but it must not be loaded down enough to get a good reading. I stopped racing for fear of buring a piston.

I like most of us feel my car is slower than it should be. I ran 12.1/115.5 with Eddy heads that had bent valves and the rest had severe leakage. Here, I have much better heads and carb and I'm slower! I'm running the stock 3/8" line and the Carter 120GPH high pressure pump 7.5-8.5?? pump.

Suggestions? Chassis dyno?

69-CHVL · Oct 25, 2008

PS - AFR meter's are cool! Never would of know I had a problem w/o one. Interesting side note...it was 50* out, and the airgap intake was cooling down so fast during those 10-15min breaks that the car had to warm up to run right! AFR meter was showing a slight miss till the intake got hot.

Additionally, the trip to the track and back is 80 miles. That plus my 4 runs and I burned less than 1/2 tank. Gotta love that OD!!

mr 4 speed · Oct 25, 2008

Vince,whats your launch technique? Cool you got to make some passes :thumbsup:

Bob West · Oct 25, 2008

I dont think its the fuel line, might want to make a fuel pump change though. Hey...ya made it home in one piece :beers:

Dave427 · Oct 25, 2008

Vince thats a nice mph. How much mph gain do you get from the 1/8 to the 1/4? Ever think about leaving on a 2 step with your stick?

Dave

HPseeker · Oct 25, 2008

Vince ,the fuel pump is a Carter 120gph or a 172gph ?

69-CHVL · Oct 25, 2008

mr 4 speed said:
Vince,whats your launch technique? Cool you got to make some passes :thumbsup:

Chris, my patented "fast release" method, leaving at around 4000. Side stepping just blows the tires off. I would need some chassis work to get this car to handle a side-step.

Bob West said:
I dont think its the fuel line, might want to make a fuel pump change though. Hey...ya made it home in one piece :beers:

Bob, pump is new, but I'm open to anything. Even though its has 3/8 fittings, they use 1/4 NPT I believe, which means the fittings are about 1/4"

Dave427 said:
Vince thats a nice mph. How much mph gain do you get from the 1/8 to the 1/4? Ever think about leaving on a 2 step with your stick?

Dave

I think my mph is way down, probably cause I'm leaning out. I dont think my car can leave any harder...it just about holds the tires now. I actually spun the tires the 1st two runs. Were talking M/T DR's here!

HPseeker said:
Vince ,the fuel pump is a Carter 120gph or a 172gph ?

120GPH.

Dave427 · Oct 25, 2008

Wow you are gaing up to 24 mph from the 1/8 to the 1/4. It sure is pulling hard for sure.

Dave

M.Maner · Oct 25, 2008

Have you tried a lower rpm launch? What size slick did you have on the car?
Mike

1968 hot rod · Oct 25, 2008

cool air, high afr = bigger jets

HPseeker · Oct 25, 2008

Why not try a single plane intake to try to give away some low end torque ?, leaving with a stick car at 4000rpm with a dual plane is hard to get a good 60ft.

JIM · Oct 25, 2008

Vince,
I have stock pickup in tank, factory line from tank to pump and a Carter mech pump so you ought to be fine there. You also picked up 24-25 Mph on the back half which is good. Multiplier from 1/8th to 1/4 is just like mine (1.54x). I feel your issue is in the first 330'.

Kevin R · Oct 25, 2008

I agree with the lower RPM take off,,, When I took the 66 427 to the track last with the TKO 600 I made my best run of 11.96 @118MPH with a 1.79 60' with a 1500 RPM launch on BFG DRs.... Any higher launch RPM I just spun and was getting 2.0 60' times. Now I have a Turbo 400 with a 3500 stall so we will see what that does for me next year,,

BTW its always a good day at the races when you make it home with no broken parts:thumbsup:
Also I run stock fuel lines and a carter 110 Mech pump

knudsonm · Oct 25, 2008

definately something amiss there. I run 11.40-11.50 @ 111-112 mph on drag radials and with some seriously butchered crappy heads. the rest of our engine combos are pretty much the same.

blue66 · Oct 25, 2008

How did the car 60ft with the ET streets?
You said you had radials on the car which are never gonna work great with a stick.

GRN69CHV · Oct 25, 2008

Prior runs with the ET Streets were in the 1.80's also. Also, keep in mind, Cecil on Friday night open street nights gets every street vehicle known to show up including 4x4 trucks - especially this late in the year. I ran there last fall on a Friday night and dropped from 1.75 60's to 1.85 60's. Launch technique and tire combo aside, there's something went the wrong way with the head swap. I think I have experienced the same thing with my own head swap. It's very possible that for the motor size and the RPM range (<6000 RPM) , the 290CC ovals may have actually been either optimum or possibly already on the large size. For me, the swap was from a 290cc GMPP/Ede to a Dart 310CC ProOne, Vince went from the same 290cc head to an AFR 305. Hard comparison because I also went to a 2400 converter from a 3000, but I lost .5 - .6 ET and 3-4 mph in the process.

A/F mix aside, here's what I think (PS - I am in the same situation). These larger heads belong on 500" motors. If ran on a 454-468" motor, the motor has to be setup to turn to 6500 -6800 RPM, not 5800 rpm. So, my gut tells there are three options. Stroker kit, solid roller (not necessarily a longer duration cam, just solid for RPM and lift) or smaller heads ( ie. 270CC ovals). One more thing, JMHO (based on personal experience), the anticipated gain in swapping to a set of high flow heads in not seen unless the cam profile has enough lift area to use it. I doubt that either the AFR305 or the Dart310 is anywhere near efficient with a .600 lift intake lobe. I would bet the potential of these heads would show up with mid-high .6xx lift.

69-CHVL · Oct 25, 2008

I know convetional thinking is that the drag radials wont work for a stick car, but I believe and confirmed last night, for what I'm trying to do, they work fine. The best I did with the regular ET streets was in the 1.7 range, and the car was ALL over the place going down the track - I hated it. These drove so nice even with 16psi that I forgot I even had them on there. For the casual racer, I think the DR's are the way to go.

But back to the combo, I need to get the AFR under control. I dont think its jetting, maybe it is. I think I would need alot of jet to drop the AFR from 14 down to 12.5-13 range, and I hate to be band-aiding a flaw somewhere. My factory 3/8 line had a crack in it right where it goes over the coil spring area, so I temp'd a piece of braided line in there. I need a new fuel line anyway. Also, the factory sock is on the pickup, b/c it fit kinda loose on the pickup, I had to hose-clamp it on. Hope the sock isnt collapsing or getting sucked in. Need to rig that fuel pressure guage I was talking about before.

JIM · Oct 25, 2008

Vince,
I am going to agree somewhat with Joe and disagree a bit with you. I still say the problem lies in the first 330'. You pick up 24 MPH in the second half. Any car with a fuel flow issue is not going to do that. Like me, you have a big heavy car with a stick shift, You need gearing, RPM and low end torque to get that load moving. Sure, you may and probably pick some more ET/Mph with optimal jetting, but I do not think that getting down in the 12.5:1 AFR range from 14:1 AFR range is going to net you a full second ET. Remember, lean is mean. I don't think you are losing much ET there.
If you had run some 1.6 - 1.7 short times ans still ran a 12.xxx, I'd say you were laying over or running out of fuel. But that is not the case.
Just my $0.02
Does Cecil provide 330' and 1000' increments? Post the entire slip, I'd like to do some more comparison between your and mine.

69-CHVL · Oct 25, 2008

Hi Jim, what Joe said regarding the heads has been in the back of mind quite honestly, but want to finish hashing everything else out before coming to that conclusion. I know lean is mean, but how lean? 14.0 is good for crusing, not making power as far as I know, maybe dangerous actually. I'm not qualified to make that call however.

Here the full timeslip of my best run. If I stayed longer, probably could of made a dozen runs, but was worried about the lean ration at WOT, so I stopped. I was slowly chipping away at the times, too bad I quit.

60'-1.87
330-5.27
1.8-8.04/88.33
1000-10.44
1/4-12.43/113.84

M.Maner · Oct 25, 2008

I'm going to assume that you will dismiss this suggestion as you have done with all the other advice given to you but here it is anyway. Consider the odds that your engine was actually running out of fuel and yet it was still able to maintain a 14:1 AFR.
Mike

10/24 Track results...

69-CHVL

69-CHVL

mr 4 speed

Bob West

Dave427

HPseeker

69-CHVL

Dave427

M.Maner

1968 hot rod

HPseeker

JIM

Kevin R

knudsonm

blue66

GRN69CHV

69-CHVL

JIM

69-CHVL

M.Maner

Top Contributors this Month

Recommended Communities