vacuum advance problem
 

got a problem guys. my 66 has an 86 model 350 in it with hei distributor. she will start right up and idle just fine but when i slowly rev it up it will start to stutter like its got a rev limiter, but when i unplug the vacuum advance she will smooth out and rev just fine and if i plug it back up it will start to stutter again. if i drive it with the advance unplugged it doesnt have any power at all so that aint gonna work lol. ive replaced my advance curve weights and springs and also replaced the diaghram that the vacuum line attaches too and its not fixed it yet. any ideas? i really hope so lol

Re: vacuum advance problem
 

It sounds to me like you have a timing problem, not a distributor problem.

I would double check that your initial timing is set correctly. Also, has any work been accomplished recently on the engine?

Re: vacuum advance problem
 

well the reason i dont think its timing is that it was running fine and then about 3 days ago it just started acting up on me, i put a new double roller timing chain in it about a month ago and it has ran perfect until now.

Re: vacuum advance problem
 

I'm just wondering because you said that it had no power with out the vacuum advance. That should not be the case. There is still a mechanical advance and when the centrifugal force is high enough (high RPMs) the engine should still have plenty of power. Vacuum is just for idle and off-idle acceleration/street driving performance.

Re: vacuum advance problem
 

a may play with the timing a little bit tommorow then, its worth a shot. thanks for the response

Re: vacuum advance problem
 

Is your vacuum advance connected to ported or manifold vacuum? Definitely check your inital timing. I would pull the distributor cap and give everything a good look and make sure everything is as it should be in there. When was the last time you replaced the cap, rotor, plugs, plug wires ?

Re: vacuum advance problem
 

its hooked to the ported side, and ive not been able to check the timing really well cause i dont have a timing light but she starts right up and ran perfect for the last few months and then just all of the sudden started this crap. i replaced the cap and everything a few months ago when i put my new timing chain in so its all up to par. and as for looking under the cap, ive had it off about 25 times in the last 3 days lol

Re: vacuum advance problem
 

I would get a timing light for sure. I once put in a cam 4 degrees off in a 350 when I was a teenager and it ran great, until you tried to go over 4000 RPMs. :lol:. I didn't have a timing light then either and just eyeballed the rotor. So double check your on #1 TDC, ensure the rotor is lined up with #1 plug wire and then set your initial timing which is probably anywhere from 4-8 BTDC degrees on that engine.

Re: vacuum advance problem
 

well like i said before, the motor has ran strong for the last few months. and trust me i have turned it WAAAAAAY over 4000 rpm lol it just started doin this out of the blue. it ran great when i parked it one night and the next morning it started this crap

Re: vacuum advance problem
 

could the coil be getting weak? i have seen this happen with the HEI...

Re: vacuum advance problem
 

Could there be a wire that is grounding out with the mechanical rotation of the distributor? Is the module tight? Do you have a coil on top of distributor or on the side?

Re: vacuum advance problem
 

the coil is on top of the distributor and ive thought about the coil getting weak, ive got a friend gonna bring one over tommorow off his truck and im gonna pop it on there and see if that helps. thanks to everyone for the replys