Does the vacuum advance keep the dizzy plate advanced or retarded during idle? Explain how it works. I think at idle, it keeps things retarded and when you gas it due to the lack of vacuum it advances it? Shed the light.
The vacuum canister uses the ever increasing engine vacuum in advance the spark. When you hit the throttle you lose vacuum, but as the engine increases in speed you gain it. You also have mechincal advance. Counter weights that swing out as engine speed increases. This is what you are working with when you are at idle.
Just the opposite actually. The Vacuum advance should be hooked up to manifold vacuum. At idle when you have full vacuum, advance is added to improve idle quality. When you open up the carb the vacuum drops off and your just working off if the mechanical. When you get up to speed the manifold vacuum increases again and the vacuum advance comes in again improving fuel economy.
Engine off, no vacuume, retarded, Easy start Engine idling, Vacuume, advanced, runs nice Accelerate, no vacuume, retards no pinging
Umm... there's more to this topic than what's been posted so far. There are two types of vac advance - direct acting and reverse acting. Direct acting systems use manifold vacuum to advance the timing, and are routed to the intake manifold. Reverse acting systems use vacuum to RETARD the timing, and the timing signal is pulled from a point ABOVE the throttle plates - known as a 'timed port'. Most SBC's and many later carbureted Fords use reverse acting vacuum systems. Finally - there is a direct/reverse system out there which has a vac line on one side of the diapragm going to the manifold and another to the carburetor's timed port. I believe this is a mid 60's Ford thing - but I could be wrong. simply put, all three systems regulate advance in conjunction with engine load so as to optimize performance and economy.
Timed ports on Holleys/Carters are not reverse acting....the just don't 'pull' until the throttle is opened......it still advances the timing.....just not at idle... Or are you talking the DIZZY is reverse acting???? Cause the same dizzy(direct) will work with either straight or timed vac***, generally idle is only affected..... But then again......I prefer mech advance only.....he he
Man .. Check the tech archives for C9's EXCELLENT post on timing...... ALL you ever wanted to know .......... ........... jersey Skip
I think you're thinking of the Load-O-Matic....of late flathead & early Y block notoriety...died at the end of the '56 model year....THANK GOD.
check this out http://www.chevytalk.org/threads/sh...aros.net"&topic=&Search=true#Post1105501 maybe it will help ya out Vance
Thanks all, we are trying to get OldBeets Merc to run like a peach and the 76 Lincoln 460 has a weird problem under heavy acceleration, pops and backfires ect. Was suspecting the vacuum advance though it seems to be working, but I think the problem lies deeper as we have changed carbs and it runs the same. I converted it to Duraspark last summer and it ran great till recently.Going to try cap,rotor and wires next.
It sounds to me like your problem is the distributor timing is too slow, try loosening the distributor and turning it to the right, if that does not fix it then you will have to pull the distributor out and turn it 1 notch counterclockwise, or maybe more than 1 notch. hope that works for you k-member!
Hey, Reds 67, this posting was from 2007, I think they probably got it running by now. You might slow down long enough to check the posting dates before jumping in...
"Vacuum advance" is one of those names that has always caused confusion for some. I've hear so many people over the years who think it advances the timing when they hit the throttle!
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