I have a 67 Malibu 250 2 barrel engine. All original. Only 137K miles on it. Just replaced wires, plugs, points, cap, rotor etc. Adjusted dwell and timing to specs. Starts and idles fine but I noticed at speeds there is a slight hesitation. Very noticable but subtle, if that makes sense. I also just noticed this. When I do the timing I always disconnect the vacuum advance. Usually when I do this the idle goes down. I noticed now when I disconnect the vacuum there is no change in the idle. The Vacuum advance is original. Could this be causing my hesitation issue? Is it time to replace it? I also threw some gumout and fresh gas in for good measure. This car has not been stored. I drive it for 6 months every year. Thanks for your help.

That sounds like that may be the culprit for sure. Make sure there is vacuum at the line when you pull the hose off. If there is you have found the problem.

Dave

Dave,

There is definitely a vacuum when I pull the hose off. I can feel the suction when I put my finger over it. Thanks for responding.

Mark

OK, vacuum in the line. What about does the vacuum adv work in the distributor?
That old the diaphram could have given up the ghost.

George,

It does not appear to be working at the distributor. I can find a new part. Is it an easy thing to replace? Never did one of these before. Looks like a couple of screws and done. Appreciate your input.

Mark

It is an easy thing to replace. The difficulty lies in reaching to the distributor. There are also some vacuum advance pieces that allow you to adjust the amount of vacuum advance you want in the engine. I don't know how "hot" your motor setup is, so it may or may not be worth your time to fumble around with one more tuning option.