Hey all, I'm relatively new to posting things on the HAMB but I feel that I am out of my depth with my current chevy 350 build. About 2 years ago I dropped a brand new crate 350 in my 1962 impala and this past summer I decided it was about time to install an edelbrock top end kit consisting of new heads, a cam, intake manifold, cam and crankshaft gears, and timing chain giving me 338 hp and 389 tq. Ever since the rebuild (completed 1 month ago), I have been having issues where on a cold start I will need to keep revving the motor until the temperature gets up to about 140 degrees or else the engine will die. Once I get the engine up to a temperature where it can keep itself running, the idle is very low (about 300 RMP's) and the idle continues to rise as the engine gets up to temperature (around 200 degrees). Once the engine gets up to temperature everything sounds good when I rev the throttle, but when I actually get behind the wheel and drive, I start getting a lot of noise out of the exhaust 2500 RPM's and up (It sounds just like a Harley.) I also feel like the car should be more responsive in the higher RPM's. I suspected that it might be a timing issue so I did a lot of tweaking of that but no matter how I have it set, the problem persists. I also thought it could be a result of my old dirty edelbrock 1400 carb, so I rebuilt the carburetor but I did not replace the jets or metering rods. when that didn't fix the problem, I tried putting different sized springs in the pistons of my metering rods but that also failed to solve the problem. I also suspected that my electric choke could be the problem but all signs show it is working properly. Could the problem be that I need to change the jets (which were fairly old and rusty looking) in my carb, or could it be a vacuum leak that I have failed to locate? I also was wondering how likely it could be that my valves are out of adjustment, due to the fact that I have never lashed valves before?
whats the timing set at , like someone else mentioned... put a vacuum gauge on it and see where its at. also, what distributor and how many miles on it since the heads and cam install? and how did you go about breaking in the cam
Get the choke adjusted properly, including the fast-idle adjustment. There is also a separate slow-idle adjustment, if you were unaware, at that may be why your normal idle speed is too low. Also, does your distributor have a vacuum advance and is it working properly? Is it connected to manifold or ported vacuum?
Until the OP provides more info and decides to join in the diagnosis , everybody's shooting in the dark.......
Wait. You didn’t adjust the valve preload / lash? At all? With a new cam and heads? Did the Edelbrock kit come with directions? Did you follow them? Sent from my iPad using The H.A.M.B. mobile app
Not sure it would idle at 300 "RMP's " with a bad cam. Probably make a bit of clickety clack too, don't you think? I too , have about 20 questions for the o/p , but I think I'll wait to see if he even comes back, first.
The Jalopy Journal
