73-84 IMSA Widebody

A Donovan aluminum 502 is the easy fix

joe flannery

I would check the advace curve on the distributor. With the cam you have- you will bleed off some cylinder pressure. That will make the engine a little lazy on the bottom end of the power curve.I dont know what kind of distributor that you are running. Get a timing light with the advance wheel and set the timing so that you have about 35 degrees of advance in by 2,000 to 2,500 RPM. You will need to use a limiter bushing to prevent it from advancing beyond that. They come in the kit with the weights and the springs. Make sure that you use it. You may also need to buy and adjustable vacuum advance unit , or otherwise you will wind up with the engine pinging at part throttle on the highway.
Crane Cams makes a kit with the Vacuum advance unit - limiter and weights -springs. Check Jegs or Summit- Let us know how you make out with it . Get the curve dialed in and will be happy with the gears. When you go to a hot aftermarket cam - You can take the stock ignition timing specs and throw them out with the stock cam. They are use ess to you now.

wiseman79

Exactly. Something more is wrong than gears.

jim2527

Dont feel bad...my 2003 C5 with 2.73's wouldnt spin the rears either.

Its all in the gears...my '06 GTO with 3.36?'s will fry 'em all day long.

comp

i'd try it

joe flannery

I would forget about playing with the carbuetor. It worked just fine the way it was- until you changed the gears.
What happened when you changed the gears is that the engine lost a bit of its mechanical advantage over the tires. Like you trying to break lug nuts loose with a 3/8" drive socket set and ratchet handle versus a 1/2" breaker bar and socket.
The engine didnt lose power when you changed the gears It just lost some of its leverage. The thing is that with the other gears the engine was able to get into its power curve sooner. I went to the Comp Cams website and they recommend a higher stall converter to help get the engine into its curve sooner , and to help with torque multiplication. With a stick car a lower gear set like a 4.11 would be recommended.
Get the ignition timing set so that you have the engine fully advanced by at the latest 2,500 RPM. The cam you have is ground on a 110 center line which is quite a bit tighter than the stock one. This will cost you some bottom end torque. This is obviosly what you are experiencing.
I would speak with a tech at Comp Cams if you have any further questions and leave your carburetor alone. A re curve kit will cost less than $20. Try it out. It will be the best $20 You will ever spend. Another thing. You will improve your fuel mileage when you are dialed in at last. If you were in my area I would invite you over and set it up for you. I mean it too . I am from New Jersey . Where are you ?

L-82kid

Thanks for the info I appreciate it, I live near New Haven Ct. If we were closer and gas wasn't 3.50 a gallon I will take u up on your offer.

Here my iginition:

Stock HEI dist.
MSD blaster II coil
MSD 6al Box
Lars re-curve kit.

I set the timing up about two years ago with that re-curve kit and I followed lars paper on how to do it. I have to find my notes on how I did it and go back and check everything. I put about 6,000 hard driven miles on it since then. So I'll take your advice and keep it out.


I had some free time yesterday so I pulled the valve covers off just to check things out. There weren't any broken valve springs or lose rockers. I ended up having a header gasket leak so I fixed that but didn't have enough daylight to check the timing.

I'll keep you guys posted on my problem. thanks for the help.

L-82kid

My car burns up the tires and launchs again. I pulled carb off again, set it up and tuned it with a vac gauge. I took my time setting it up but still need to play with it. My timing is 36 deg total timing all in by 3500rpm. The carb is set up down one jet size then I had it with the 373s.

The car sounded like it was running better. I took it out for a test run on a back road. I dumped the clutch at 3000-3500rpm just to see if there was any different. The tires broke lose and I fishtailed. Left two long burnout marks. Then I made a few practice launches and ran it through the gears. But now Its hesitating slighty when going from 1st to 2nd or 2nd to 3rd. It run great through the gears before and bogged hard off the line, now the power is back off the line and hesitates a little up top. lol I kinda hate this speed demon carb but i guess I'll keep playing with it to get it perfect.

thanks for the help guys

comp

have you tried more accelerator shoot ???

Alwyn678

Or my favorite 3.73's

USALT1

Did you put your original jets back in? Sounds like you might be leaning out a bit, also make sure there is no play in the accelerator pumps, even a tiny wink of slop will cause bogs. Going from a 3.73 to 3.36 shouldn't affect doing a burnout, just rev the engine a little higher & pop the clutch. Whit will affect most is your 1/4 mile times.

L-82kid

I thought the same thing. But when I dumped the clutch (even at like 4000-4500rpm) the car would chip the tires then bog down so hard it would come to a stop and almost stall out. I tried lauching at several different rpms and still the car would fall on its face. but if i was going like 2800rpm in 1st or 2nd and punched it, the car would rip and had no hesitation at all. So I pulled the carb off, went from 76/83 jets to 75/82 jets. Then tuned the 4 idle mixture screws. then are 1 5/8 turns out from seated. I went for a ride and dumped the clutch at 3500rpm and the tires smoked up and I went sideways. But now when going 2800rpms in 1st or 2nd the car hesitates.


I already checked the accel pump arms and they're good. they shoot gas even at the slightest touch of the finger.

I really want to get this car dailed in, I wish I knew what the hell I was doing. lol