Gipper

Did a basic tune up this weekend as the car is new to me, and I and trying to trace down a mid throttle surge that I get at speeds above 55mph. I changed the plugs, cap, rotor, set dwell to 30 degrees and set the timing to 7.5 btdc at 850rpm per the charts (distributor vacuum pluggfed off), it was at approx. 14 degrees. The motor is a HC 330 with a 4bbl Rochester on it. My question is in regards to idle speed after I set the timing. As I said I set it to 850rpm but when I reconnect the distributor vacuum it goes to 1250 rpm. Should I just turn it back down to 850 rpm with the vacuum connected? Or do you guys prefer the 550 rpm in drive setting? I realize each motor may be a bit different but what is the standard here?


Thanks - BRian

oldcutlass

Just turn the idle speed back down, I prefer the 550 in drive setting. My 330 engine preferred the vacuum adv connected to ported. Did you replace the fuel filter? Does the timing fluctuate? What vacuum do you read, does the vacuum fluctuate?

Gipper

I do not have a vacuum gauge at t he moment but the timing with the distributor plugged stayed very steady.....I will check it again with the vacuum connected and the idle adjusted.


Brian


Thanks for the quick reply.

Gipper

Ok dropped the idle to 850rpm and checked the timing again. The mark is steady but it is advanced to about 20 degrees,,,,,guessing as marks only go to 10 degrees.
















Brian

oldcutlass

The timing will be advanced as your vacuum canister is hooked to manifold vacuum. Have you changed you fuel filter recently?