jb1289610

hey guys. got an 84 camaro with a 350 in it. if i'm barely on the gas or if its floored the car does just fine. but when it's under partial throttle it shakes real bad. i know the carb has bigger jets in it so i was thinking that the motor was getting too much gas and causing it to act funny. it'll also backfire sometimes when floored from a stop or will even sometimes die. what the hecks wrong???

pancherj

Sounds like a lean surge. Are you running vacuum advance? If yes, then at part throttle the vacuum is high so the timing advance goes high. If the carb is lean at that point, you will get surging.

Make sure it is not shaking at a certain RPM (which happens to be at part throttle). If it is just happening at a certain RPM, then it may not be the carb at all. It could be an engine balance issue.

jb1289610

i checked today and it is at a certain rpm. how do i fix this? it's quite annoying

pancherj

If it is occurring at a certain RPM only, I would first look at wheel imbalance and if it isn't that, I would start looking at the engine. If it is the engine, it should shake at a similar RPM in park also...so you can check with the hood open.

I had another thought...It is possible it is the torque converter lock up malfunctioning. I have heard of this, but never experienced it personally.

jb1289610

if it helps at all i just had a 350 turbo transmision swap done on my car.

jb1289610

the shaking doesnt happen at all in park. and it isnt the steering wheel. its just at around a 1/4 throttle at lowish to mid range rpm the car shakes like crazy cause of the motor. it shakes the whole front and my dash. i know its not the steering cause thats steady. its the body panels and the dash and stuff that shakes. and it doesnt happen at low rpm's or when the motors screaming. whats going on?

pancherj

I missed the part in your original post where you mentioned backfiring through the carb when you floor it. That could certainly be timing related. How is your timing curve set up? I still think the kind of shaking you are talking about isn't carb or timing related. It sounds too violent. If the engine was detonating that bad, it would have killed a piston by now.

taonindo

check your motor mounts