I`m sorry but i did not understand your question. That doesn`t mean anything , but please try again. I have never heard of a non- vaccum advance dist. and would like to learn. Ofcourse i am old too!!!
Slider in Wa.
HEY 69: I have been doing some studying about timing. Found an article that stated " However many factory and after market performance distributors do not have even come with vacuum advance. The reason is simply because race cars do not spend much time at part throttle". It sounds to me like if your only mode id WOT you probably don't have to worry about vacuum advance. If you look on this site under " ARTICLES" and punch in TIMING there are a number of tech articles that discuss the different type of distributor adjustments and their relationship. I hope this helps, if not give me a shout I have found a number of sources for tech info. GOOD LUCK DAVE
i know mallory makes non vacumadvance distributers but i dont know if they are for high performance or not. i was asked when i bought my distributer if i wanted with or without vacum, i should have asked then whats the differance!!
all vacuum advance does is increase low to part throttle driveability, also helps gas milage, all the old high perf distribs were non vac, you don't need it on race type motors. if you drive at less than three thousand rpm, you will notice the difference.
as they say non vac for race cars if you want to taylor u ign get a adjustable vacuum adv from hi-perf co [under 30 bucks stock don't know about carban if car doesn't hessitate you can do with out it if gas milage is not a problem
Some of the older stuff, like 1950's maybe early 1960's, had MECHANICAL advance, not vacuum advance. It used weights and centrifugal force to advance the distributor.
Chevys need vacuum advance if driven on the street. Although a high performance distributor without vacuum advance will give you very quick throttle response, when you get stuck in traffic it will also help your motor to overheat. Some of the newer computerized systems take care of the timing advance with electrons so it doesn’t look like they have one. Trust me though, for everyday driving you really need a vacuum advance setup. Adjustable vacuum advance seems to work very well for street/strip use so if you do some part time racing that may be the way to go.
At one time (many moons ago) it was fashionable to disable the vacuum advance feature thinking that it would improve performance as many factory muscle cars (early/mid-sixties) came from the factory with mechanical only distributors.
What most overlook is the need to recurve the timing curve to drive on the street or for track use. For a mainly street driven engine (pre ECM} you want to have the vacuum advance feature.
If you see occaisional or frequent strip duty, you may want to have a spare distributor set up for track only.
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