Vac advance, ported or manifold?
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Max Power..................... just off throttle under acceleration..................[/QUOTE said:WTF does this mean?
I know what under acceleration means, but what does the "just off throttle "part mean? If you are off throttle, does that mean you are unaccelerating? How can you do both at the same time?
Hmmmmmmmmmmmm?????
this thread needs to be locked 
Max Power said:
Hey, I gotta be me.
Your discriptions about this issue have lead to some of the miss information in this thread. You are just now starting to explain yourself only after being questioned. I accept that ported vacumm goes down in the upper reaches of the rpms. But, I say again that ported vac increases up to a certain point and that point or points under that rpm range is where the majority of us do our driving. So, ported vacumm is benificial to fuel economy and performance.I posted this on the first page of the thread:
""""Actually, vacuum advance is pretty high at freeway cruising, as is vacuum. When you mash the throttle, timing retards a little cuz vacuum drops. Prevents detonation during higher cylinder pressures of WOT driving. Think of vacuum advance as fine economy tuning for mechanical advance. Vacuum allows more advance during light throttle cruising, which improves economy. When you mash it, it goes away. In the days of just mechanical, it would just run a little more retarded all the time.
It's a fairly fine tuned system, and anytime you make any engine mods, you alter it's effectiveness. That's why so many people with heavily modified engines just go to straight mechanical. Economy is less of a concern and it's hard to make mechanical and vacuum advance work perfectly together on your own.""""
While I occasionally stumble on my descriptions, I don't think it gets much clearer than that. Off throttle and off idle are commonly used terms that mean the same thing in the trade. The rpm that vacuum declines on ported turned out to be a little higher than I thought, after I hung a guage to look. At least I hung a guage, which is almost as difficult as clicking on many of the links provided.
I never questioned the benefits of vacuum advance, I just questioned that ported vacuum increases across the entire rpm range. I have no idea where you got that idea that I questioned the benefits of vacuum advance through a ported source.
That is counter to how vacuum advance is designed. To have it continue to increase over an the entire rpm range would result in far too much advance during high cylinder pressure situations, like WOT or high rpms, which would lead to engine damaging detonation.
I have tried to be civil through this discussion. I would appreciate the same consideration.
""""Actually, vacuum advance is pretty high at freeway cruising, as is vacuum. When you mash the throttle, timing retards a little cuz vacuum drops. Prevents detonation during higher cylinder pressures of WOT driving. Think of vacuum advance as fine economy tuning for mechanical advance. Vacuum allows more advance during light throttle cruising, which improves economy. When you mash it, it goes away. In the days of just mechanical, it would just run a little more retarded all the time.
It's a fairly fine tuned system, and anytime you make any engine mods, you alter it's effectiveness. That's why so many people with heavily modified engines just go to straight mechanical. Economy is less of a concern and it's hard to make mechanical and vacuum advance work perfectly together on your own.""""
While I occasionally stumble on my descriptions, I don't think it gets much clearer than that. Off throttle and off idle are commonly used terms that mean the same thing in the trade. The rpm that vacuum declines on ported turned out to be a little higher than I thought, after I hung a guage to look. At least I hung a guage, which is almost as difficult as clicking on many of the links provided.
I never questioned the benefits of vacuum advance, I just questioned that ported vacuum increases across the entire rpm range. I have no idea where you got that idea that I questioned the benefits of vacuum advance through a ported source.
That is counter to how vacuum advance is designed. To have it continue to increase over an the entire rpm range would result in far too much advance during high cylinder pressure situations, like WOT or high rpms, which would lead to engine damaging detonation.
I have tried to be civil through this discussion. I would appreciate the same consideration.
You know you like to do it 
Max Power said:LOL, so it's not just me, huh?
No, most old timers on here have had to suck it up when faced with newbs and the like. It comes with the turf. We usually either resolve the issues or just decide to give it a rest. Fortunately, I have a good relationship with Stangers in the know.
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