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 Vacuum Advance Help 
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Joined: Wed Jul 08, 2009 3:40 pm
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Location: Knoxville, TN
Post Vacuum Advance Help
Who has the most experience with tuning vacuum advance? Don't be shy if you know what you are doing. I need to ask a couple of questions. Thought I got mine all straightened out, but it is still acting up on me a little.

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Tue Oct 13, 2009 9:15 am
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Location: Parrottsville, TN
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Post Re: Vacuum Advance Help
Woody would be your man.

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Tue Oct 13, 2009 11:46 am
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Post Re: Vacuum Advance Help
What is it doing?

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Tue Oct 13, 2009 11:54 am
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Location: Knoxville, TN
Post Re: Vacuum Advance Help
It is just really inconsistent. Some days I drive around and it idles at about 650-700rpm. Later that day, when I come to a stop sign it might idle at 1000. I have the advance set to come in at about 13 inches and it is full in at 23-24 in. I have it set late for highway cruzin to help with mpg....but on days when it feels like revving up to 1000 it starts advancing, and when I put the truck in park she is revving at 1500 rpm and advance to like 36 degrees. I don't get it. Honestly now that I think about it, it did this some before I even had the vacuum advance hooked up, but with the advance it is worse. I just don't understand what can cause such inconsistency. Should I set set it to come in lower? Just getting a bit PO'd.

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Tue Oct 13, 2009 1:22 pm
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Location: The Netherlands Europe
Post Re: Vacuum Advance Help
sound more like youre having a vacuumleak somewhere could be the manifold to the heads or the fitting of the carb to the manifold
you should be able to find it if its a leak by spraying some WD40 or rustbuster type stuff around gaskets and hookups of the manifold with a running engine and listen for sputtering and look for smoke out of the exaust
if you work small bits at the time you can pinpoint the leak pretty acurate and might be able to fix it with a dab of siliconekit


Tue Oct 13, 2009 2:29 pm
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Location: Knoxville, TN
Post Re: Vacuum Advance Help
already tried with a can of brake cleaner....no leaks.

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Tue Oct 13, 2009 2:46 pm
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Location: Sevierville, TN
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Post Re: Vacuum Advance Help
What kind of carb are you running?

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Thu Oct 15, 2009 4:44 pm
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Post Re: Vacuum Advance Help
Speed Demon 750 Vac secondary

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Thu Oct 15, 2009 5:43 pm
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Post Re: Vacuum Advance Help
Runs like a scalded dog wide open....just have trouble getting it to idle consistently.

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Thu Oct 15, 2009 5:44 pm
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Post Re: Vacuum Advance Help
I think I am going to try to run the vac advance on the ported side......

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Thu Oct 15, 2009 9:21 pm
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Location: Sevierville, TN
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Post Re: Vacuum Advance Help
Yes, run your vacuum advance ported. How does the engine idle otherwise? I've heard Demon carbs have to have the butterflies adjusted to smooth out at idle.

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Matt
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Fri Oct 16, 2009 11:34 am
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Post Re: Vacuum Advance Help
Yeah...I ain't gonna lie they are kind of a B&#$% ti get to idle, I thought I had it all worked out.....didn't even think about running it ported until yest....been bugging me all week. I should of thought of it since that is the way it is essentially set up to run. Any recomendations on when to set the advance to start coming in? idles around 8 degrees.....cruizing around 15-25

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Fri Oct 16, 2009 11:41 am
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Post Re: Vacuum Advance Help
swapped to ported....called Barry Grant tech....they helped me out...everything was set pretty much correctly, just one little set screw that adjusts the secondary butterfly valves..... :banghead:

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Fri Oct 16, 2009 3:12 pm
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Post Re: Vacuum Advance Help
So your good to go now?

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Matt
:flag: Thanks to our soldiers and their services. :flag:

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Mon Oct 19, 2009 11:52 am
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Post Re: Vacuum Advance Help
pretty much...I may change out the power valve to a 5.5....i think it would help with light throttle stumble I am getting....I almost got everything worked out.

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Mon Oct 19, 2009 12:58 pm
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