Platform - 69 Cutlass
350 rebuilt (Don't know specs, was told it did get a bigger cam)
HEI
Performer RPM Intake
Edelbrock 600 CFM Carb
Autolite 86 Plugs gapped to 45 (Tried at a few different gap settings, then checked here, consensus said to gap to 45)
Accel Wires 8mm
12ga wire running to Dist directly from fuse box


First, after installing the Intake and Carb it ran great but since I used the rubber in the front and back it blew those out. I since replaced the gasket again and it seems to be holding using the RTV in front and rear, however, now the car has developed a surge when picking up speed, holding a constant speed, and off idle it kinda bogs a tad under light load.

It has all new vacume lines, no physical leaks that I can tell, I even used the old method I was taught, spraying a tad of ether around carb base, hoses, intake, etc and see if the engine RPM's go up. It didnt change no matter where I sprayed.

I then decieded to try changing plugs and wires to see if this was part of the problem, and to no avail. I am also getting a wierd shift on the transmission that never did this before. It will wind out and act like its slipping from 1st to second at WOT and it will act like a slip for a long time then shift extremely hard. The guy that sold me the car said it had a shift kit in it, but even still it's not suppose to do this, and it never did this before the new intake gasket. Which leads me to think vacume leak again, but I can't find any noticable leaks

At this point i'm not sure what can be causing this. Timing hasnt moved one bit. All wires and connections to Dist, battery, starter, Alt, ignition etc are newer wires, 12v sources and I have double checked it all. I have the VaC going tot he ported side of the carb and the transmission going to the Intake side as supposed to go. At idle and under load the car runs great, it does kinda stumble but I believe this is formt he cam as you can hear it chugging away. It has "some" power, not the power I would expect this car to have, and the pickup is pretty decent, it's just the surging and shifting that has me stumped.

Could the timing be off at a higher RPM causing the surge?

Are there better plugs to run in the car with my current setup?

Should I try removing the transmission VAC line from the carb and go directly off the intake fitting?

What about VAC Advance, is there another place I can try running it off of besides the carb?

Any feedback or help would be appreciated.

Thanks,
Brian

 

Anybody? Need to, must, get, the, car, running, right.... ugggg Need some input.

 

Fuel pump??

 

Yea, thought about that, but the owner before me ran all new lines from tank to pump. The pump that was on it seemed pretty new, but I replaced it anyways just this afternoon just to be on the safe side but it didn't help.

I'm gonna try to adjust the timing a tad tomorrow and see if it helps any on that issue. Just odd that it didn't do this before the first set of Intake gaskets blew out, and now it does. I know it's something I've done and missed, just don't know what.

 

What transmission?

 

350 Transmission

 

First guess since TH350 would be to check vacuum supply to transmission vacuum modulator (on trans). I would plug the vac supply to it & see what changes. I would think if bog went away(lean bog due vac leak) & shift still not right you probably have a leaky diaphragm in modulator.

Check for vac leak @ advance canister too.

These would be the first things I would check - FWIW!

 

Ok, this might be a stupid question, but where is the vac canister? My line goes from the Modulator on the transmission to the Intake port on the Carb. It's a direct line with no breaks.

 

Vac mod line I believe is usually manifold vac as you have it.

Vacuum advance canister(diaphragm) is on distributor supplied by ported vacuum off carb(above throttle plates) also as you have it.

Check advance canister by popping dist cap, hook vac pump to advance canister & apply vacuum. You should see the breaker plate(points)/Pickup ring(HEI) move as the vac is applied & then return as vac decreases. If you get no movement, canister's diaphragm is no good - could be a contributor to your problem.

 

Ahh gotcha I will check all this when I get home from work tonight.

 

You may have to use a vac reserve canister if cam is very large. Once the vac issue is solved and flat spot or bog still exists larger carb may be needed....good luck.