1964 Pontiac StarChief erratic idle

EHALL09

MEMBER
1964 PONTIAC STARCHIEF
V8
2WD
AUTOMATIC
97,000 MILES

I have a 1964 Pontiac Starchief with a 389 I recently put on a 4 barrel manifold and a new edelbrock 600cfm carb (electric choke). When I finally get it to start it idles extremely rough idling high then low then it eventually just gets reving high and stays there. If I hit the throttle it idles erratic again then revs high. I thought it was a vaccum leak and sprayed choke cleaned around all the gaskets it did not change the idle indicating a vaccum leak. I then replaced all vaccum hoses, the pcv valve with the grommet was replaced as well (pcv valve is located on the crankcase behind the intake manifold). I then took the vaccum hose off from the break booster thinking it was a leak inside it and caped the hose off and still no change. The engine was doing this before I even replaced the carb and intake manifold so im running out of ideas. Please help.

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Check to see if you have a spring type clip holding the distributor in. If you do the distributor may have popped up around it. You can fix this by getting a solid hold down to hold the distributor in the block. I thnk a chevy one will work. You might also check the distribuotr weights under the rotor, you may have a broken spring or one off of the pin that holds it in place. You can usually find a racetype setup and use the lowest one they have to give you normal type driving. Also check the vacuum advance and breaker plate. I definitely think this is a distributor problem. Another thing to maybe check is the timing chain. Pontiacs for that period are well known fo rhaving chain problems. If you ended up getting 40,000 on them then it was on borrowed time.