jonas need help to clarify doubt about: : what is the difference between a mechanical and vacuum advance distributors?
i dont know what distributor would work better for my chevy 383 stroker motor.
would a vacuum advance be easier or a mechanical my chevy 383 is in a 1970 pontiac gto .
Try this:
Answer by don d
I would use a vac advance on that vehicle ,be easier than adjusting timing periodically.
What do you think? Answer below!
Vacuum advance uses the engine’s vacuum (a vacuum hose attaches from a vacuum advance unit in the distributor to the bottom of the carburetor) to advance the timing in unison with the increased rpm
Mechanical advance uses weights and springs inside the distributor, to advance the timing.
In the old, old days, the timing was controlled by the driver, by a lever , sometimes on the steering wheel.
Application applies here. For street you really want a vacuum and mechanical combination. It gives you way better fuel economy. Pure mechanical distributors are for the race track where wide open throttle is the normal mode of operation. I would recommend an HEI distributor, however, I think it will not fit, due to firewall limits. My friend ran a stock distributor in his 1965 El Camino hot rod 350, and it worked just fine. I run a stock Chevrolet distributor in my 1974 Nova 350. No problamo.
i own a repair shop,and you need a msd ignition system on it with a vacuum,and mechanical advance unit on it,,and you don’t have to keep adjusting the timing on it,i do this 6 days a week and i have a stroker engine,,i haven’t set the timing on it in months,,and it runs fine,,ask at any advance auto parts they can show you what you need to make it run good,,hope this help,s.
You ALWAYS have mechanical advance on a distributor, and usually you also have vacuum but you can disconnect the latter.
Mechanical advance is controlled by weights on springs, spinning on the dist. shaft. They advance timing as RPMs increase. Mechanical advance is necessary if you want to rev over 2000 RPM, so it’s always there even if you don’t think you have it. ALL distributors have it.
Vacuum advance is there purely for efficiency. It forwards the timing based on engine load. High vacuum = low engine load, so the engine can run more timing with no problems and deliver better fuel economy. The round vacuum can on the side of the dist. does this. You can disconnect the vacuum line (and plug it) to do without the vac advance if you want.