y car is a 1991 Chevy Camaro, has a th700-R4 with a shift kit, corvette servo, better clutches, etc. As far as I know, the stall speed is at roughly 2000 RPM.

350/360HP


-9 to 1 compression
- Hydralic Flat tappet camshaft .480" valve lift 230 duration @ .050"
- 76cc Heads with 2.02" Int./ 1.600" ex. valves, 1.250" valve springs
- Edelbrock Performance RPM Alunimum Intake manifold

The problem I am running into, is when the car is in neutral or park, it idles just fine at about 800-900 RPM, without much deviation. Very little actually.

When I drop it into gear however, it lugs down to roughly the 300-400 RPM range. It does this in any driving gear.

When I have it on the road, and driving, the breaks don't seem to work correctly, and when I give it anything more then roughly 2000-2500 RPM, the car stalls, and doesn't want to get any more power. is this because the secondaries aren't opening up at the right time?

I tohught I had a vacuum leak, which would also explain why my power breaks aren't working, but I don't really know how to check for vacuum leaks.

I'm rackin my brain trying to figure out how to fix these problems. I have the Holley 670 CFM Street Avenger carb, and Im pretty sure I got different springs to put in for the secondaries.

I know part of this is probably my own dumb fault cause some stuff is mismatched, but if so tell me tactfully, don't come right out and say im an idiot....im learning, and im trying...thats whats important, so please keep that in mind.

I hope that that is enough info, and I thank you for any help that you can give me! Thank you very much.

 

It's because you have terrible smog heads which give you low compression; and too much cam for the amount of compression you do have.

The carb is about right for the engine size and RPM band and all that, and the intake should be OK as well.

The best thing you could do would be to lose the smooger heads, and get some better ones. In order to do that, you need to know exactly what pistons are in it.

Basically, you have one of those combos, that gives very low idle and cruise vacuum (which is why your brakes suck), and poor low-end torque because of the too-low compression and too-much cam, and no high end power because of the poor flowing smogger heads. It all adds up to a difficult situation to tune a carb for.

Make sure your brakes have their vacuum line hooked up, which should most likely be to the base of the carb, and that the kine isn't blocked or anything; make sure your PCV is hooked up properly as well. Look to see where your distributor vacuum advance is hooked up to; it should probably go to the "ported" vacuum port on the carb, which is the one that doesn't have vacuum at idle, but instead, starts to have vacuum after the throttles are opened a bit. Set the static ignition timing to about 15° advanced, with the vacuum advance line disconnected. Then go to the Carb board on this site and do a search on my userID and the word "transition", and follow the instructions for tuning Holleys.

Those things should help out until such time as you can get a halfway decent set of heads in there.

 

wow this is REALLY old, but your wrong, its not the heads. Its timing and my rear gearing and AT THE TIME I didn't have the right stall converter in there. I have a new stall converter (higher and matched to the engine) and this thing takes off like a bat outta hell from 1-2 gear. Still hits a wall in third, but I'm going to be putting in the higher geared rear into it, and tuning it with my friends dad who used to race carbed cars and tune em, he knows his stuff. ( he also doesn't think they are crap smog heads )

cheers

 

amazing what setting the timing correctly will do! for awhile my timing wasnt set right and it was a dog!