I changed my timing chain on my Buick 350 after finding out someone had it on 40 degrees advance at idle and if i lowered it it would die and my idle could never go below 1200 in park no mater how much i messed with the carb , so i figured maybe my timing chain skiped when i took it apart the dots were still lined up but there was a lot of slop in the chain, after taking it apart and changing the timing set it seems the car runs worse and still demands 40 degrees advance. I am stumped. I need yours guys advice on what to do next, thanks
Is the engine completely stock? If not, what has been modified on it? Cam, intake? Carburetor? Distributor?
OK, a stock engine should make 18-20" of vacuum fully warmed up, idling in Park. If vacuum is low, you have a vacuum leak. It maybe internal from a poor fitting intake. That would be one reason it needs so much advance to idle. Buy a vacuum gauge and check. Also, one of the reasons Q-jets get such a bad rap is because they are not cookie cutter carburetors like Holleys. Each Q-jet was calibrated for the engine family it was intended for. You cannot put any Q-jet on any engine and expect it to run right. There are guys right here on V8 that can build and calibrate a Q-jet for your engine specifics.
That could be all wrong as well. HEI distributors tend to have too much mechanical advance built into them. That makes it necessary to run retarded initial timing so that you don't over advance at higher RPM.
it has 20" pounds at idle. i bout the car with the carburetor on, but the part number on the side comes up as chevy. i try to put my edelbrock on but it just wants to die.
it ran okay on the freeway it was just at idle it seemed to have a miss fire and idle high. it was derivable though.
20" at idle is very good, but you are at 40* ignition timing at idle. That could be artificially increasing vacuum. Can you adjust the distributor for less timing, or do you run out of rotation because the distributor cap hits the intake?
1. "Dots lined up" means squat. Is there more than one set of "dots", like a multi-keyway timing set? Is one timing gear mis-marked? DEGREE THE CAM. This will also require you to... 2. ...VERIFY the timing mark on the damper is actually aligned with the TDC pointer on the timing indicator. 3. If the carb has it's ID numbers, it's not a "random Chevy carb", it can be traced to model year, and perhaps engine and body-style application.
Maybe the timing is covering up a the real problem like vacuum leak or bad carb. Recheck firing order on plug wires also.
Is the vac advance on the distributor on the correct line out of carb? Also is the distributor pointing at the #1 tower when the piston is at TDC on the compression stroke? and the pointer on the timing tab pointing at "0" at this point.
I would verify the timing mark on the balancer is correct. A spun outer ring would account for your bizarre timing issues.
I second the ‘check your balancer’ recommendation. It sounds like you have more than one problem and you you’ve figured out that the timing set wasn’t one of them. Probably needed replacing, but wasn’t the problem. Patrick
