Engine Performance problem
1968 Pontiac Bonneville V8 Two Wheel Drive Automatic 120000 miles
I'm just about at wit's end.
The motor stalls on idle. It doesn't seem to matter where I tune the idle mixture screws on the carb base, still stalls. After revving it in the driveway and the motor decreases to idle it wants to stall unless I partially close the choke (increasing vacuum pressure?). It gets worse after the motors warm, even worse when its hot. I can pull out of the driveway OK, but once out on the street, even coasting in neutral, it stalls.
I've done quite a bit so far: I've partially cleaned & rebuilt the 2-barrel vintage Rochester carburetor (set the float twice), rebuilt the ignition (still waiting on the correct contact points assembly) & checked all the vacuum lines. There's no EGR valve (1968 Catalina actually, but very much like the more-optioned '68 Ventura, Bonneville or Executive).
I say "partially" on the carb rebuild: When I rebuilt the carb I just cleaned out the circuits using a straw nozzle from a spray can with some help from a nylon pipe cleaner. I didn't soak the carb however.
I wish I could just adjust the maximum choke intake opening, that'd keep the vacuum pressure up during idle. Should I go ahead & pull the carb again & really soak the base in a bucket of carb cleaner?
What else should I be looking for? I really appreciate any advice you have to offer. This is a beautiful car but this mechanical problem is becoming an obstacle in getting on with the rest of the restoration work.
Thanks in advance,
have the same problem?
Tuesday, April 22nd, 2008 AT 12:50 PM