I just built a 350 for my other car (not the 70 Camaro), and am running a Comp Cams XE268 cam with 1.6 rockers (specs below). I have a new distributor, and new Holley carb on it.

The car idles and sounds great when you set it where it should be, but when you put it in gear it stalls...

If I bring the idle way up and drop it in gear it will barely stay running and is already stalling the converter (it's trying to surge and pull the car along) but if I bring the idle ANY lower it causes it to stall again..

Once you get rolling out on the road it feels good..

I have the timing set to about 34deg full advance right now using a dial light.

The distributor is running of the "timed" vacuum port on the carb right now.

Is the stock converter just too tight for this cam, or is there something else I should be looking at?


The cam specs are below..
I am also running 1.6 full roller rockers
that bring the lift to .509 on the intake and .512 on the exhaust

Part Number 12-242-2
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS XE268H-10
Description
Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.477 0.48
Duration At 0.006 Tappet Lift 268 280
Valve Timing At 0.006
Open Close
Intake 28 60
Exhaust 74 26


These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 224 230
Lobe Lift 0.318 0.32
Lobe Separation 110
Edit/Delete Message

I've had the exact same problem before. Your cam is too large for the stall. Change it out and you'll be in business...not to mention being a hell of a lot quicker off the line.

I've had the exact same problem before. Your cam is too large for the stall. Change it out and you'll be in business...not to mention being a hell of a lot quicker off the line.

Grrr.. Comp Cams said that this cam was OK with a stock coverter :mad:

I had a 3400 stall in it with the last motor that had almost the same cam, but that was WAY too loose for the street and I am converting it back into a driver so I thought the stock converter would be allright :shy:

I have a much larger cam in my car than that and it idles ok in gear. The car rocks from one side to the other but thats just the cam. I would check to see how much vaccuum you have at idle while in park and in gear.

My old IROC used to do that when I first put my heads/cam motor in the car...even w/ a 2400 stall. Cam was a Comp XE270 .495/.502 218/224.

Try running the timing w/o the vacuum advance hooked up,adjust it w/ springs and weights...thats how I got mine to run good and idle good in gear. Friend of mine has a monte carlo we put a .480/.480 - 24X/24X - 108 LSA cam in and had to do the same thing on that,but hes still running a stock convertor.

I've run a cam that big with a stock converter and didn't have an issue.. Yeah, it wasn't as quick off the line, but it idled fine for a cam that big. Never had an issue. Plenty of members here are running the next step ( XE 274 ? ) up on a stock converter. Surging typically isn't a convertor issue.

Some things you've probably already done :

I'd check a few other things before pulling the converter. Recheck the carb, surging doesn't sound right and indicates a mixture issue. Block all the vacuum ports ( including the brake line ) and see if the issue goes away. Triple check for vacuum leaks. I've got a really cool clear glass spark plug for checking mixture at idle, but now you can get O2 sensors that will do the same thing. Just make sure you get the pre-heated variety, non-heated ones suck for checking idle cause they never get hot enough.

Timing might be an issue as well. Pull the vacuum line, and set the timing to 12 BTC. See if it idles then, your advance 'can' might be bad. I'd also check to make sure the advance springs and weights are not broken/worn. They could be messing with the timing by bouncing around at idle. You said it's a new distributor, but maybe one of the springs or wieghts slipped off during install. Make sure the timing is rock solid at idle, no bouncing or jumping around.

Spending the hour or so checking, and double checking, top side sure beats the afternoon and $$ you'll spend on your back, especially if the new converter doesn't fix the issue. Been there, Done that, got a box of parts to prove it..

Maybe surging wasn't the best way to describe it..
The engine don't surge, but if you sit at idle in gear you can feel the converter try to pull then ease off then pull then ease off, but the engine itself is pretty steady.


I'll try a few of the things mentioned this weekend and double check everything else and see if I can get her to idle..

Thanks for the replys so far ;)

Mine did that when the convertor broke.

I agree, not a converter issue. Sounds like either a timing, mixture, or vacuum problem. How much initial timing are you running? How far out are the mixture screws. What is the car currently idling at? Could also be misadjusted valves. Those are my best guesses. Good Luck