Question, a little basic, but it is my first mech advance distributor
07-25-2003, 12:49 PM
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Question, a little basic, but it is my first mech advance distributor
What is better vac advance or mech advance. I was thinking my first upgrade to my 68 was going to be all new ignition (everthing looks pretty old). I noticed it had no vac advance and I have never had that before. When going for the new stuff should I stick with mech advance or change to vac as long as I am there? I have never adjusted a vacum advance and they seemed to work fine, what do you need to know about mech advances to adjust them, if needed?
07-25-2003, 12:55 PM
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Re: Question, a little basic, but it is my first mech advance distributor (BigBadOrange)
They are not mutually exclusive, you can and should run both on a street driven car. Go to the tech section and look up Lar's paper on setting timing, that will set you straight. :thumbs:
Here is the link:
https://www.corvetteforum.com/techti...=109&TopicID=3
[Modified by Fevre, 12:55 PM 7/25/2003]
Here is the link:
https://www.corvetteforum.com/techti...=109&TopicID=3
[Modified by Fevre, 12:55 PM 7/25/2003]
07-25-2003, 01:22 PM
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Re: Question, a little basic, but it is my first mech advance distributor (Fevre)
Checked it out, nice article. The distributor on my car now is a mech advance only. SHould I replace it with the same, or go vac advance. Is one better then the other, why or why not?
07-25-2003, 04:22 PM
#4
Le Mans Master
Re: Question, a little basic, but it is my first mech advance distributor (BigBadOrange)
That all depends on your paticular set up.My BB will not handle ANY vacuum advance, I just run with the mechanical and even that is limited to 26 deg instead of 36-38. Vacuum advance is strctly an economy thing.
07-25-2003, 04:45 PM
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Re: Question, a little basic, but it is my first mech advance distributor (bluevetteman)
A standard distributor has both vacuum advance and mechanical. The vacuum advance, amongst other things, will advance the timing enough to keep the engine from overheating at idle. To me, it's an essential part of a street car, but obviously not required on a non street car. The mechanical advance (the weights inside the distributor) can essentially be tuned by putting different tension springs in them to quicken or slow the rate of advance. Lars posts and papers are essentially "the bible" on all this stuff....
Essentially you want somewhere around 36 to 38 total advance, with approx. 12 initial timing and enough vacuum advance to match your engine vacuum profile. Granted this is my SBC knowledge and BBC may (or may not) be different. See SWCDuke's posts (mostly in C2/C2 section). He, like Lars, is very knowledgeable. Good luck!!
Essentially you want somewhere around 36 to 38 total advance, with approx. 12 initial timing and enough vacuum advance to match your engine vacuum profile. Granted this is my SBC knowledge and BBC may (or may not) be different. See SWCDuke's posts (mostly in C2/C2 section). He, like Lars, is very knowledgeable. Good luck!!
07-25-2003, 05:10 PM
#6
Le Mans Master
Re: Question, a little basic, but it is my first mech advance distributor (68shark)
Early BB's are not tolerant of too much timing advance. Unless of course you run 98 octane. Totally different head and combustion chamber design has a lot to do with that