Edelbrock AVS - distributor vacum port

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k3522

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I just installed a new Eddy 650 AVS and it is great. Went to Albion, Pa Mopar show and 70% of the cars with my carb had the distributor vacum hooked to the passenger front port (timed vacum) and 30% had it connected to the driver side front port (constant vacum). Why and which is right?
 
Ported vacuum is were the vacuum advance is supposed to go, like how you have it. If you put it at the full vacuum port it could have to much advance at idle.


Chuck
 
Mine actually preffered full vaccum it seemed, ran good in either port. Throttle was a little snappier hooked up to full manifold, never had any issues. After running the cutouts most the time i did away with the vac advance instead of tinkering with it. lol
 
If you run better hooking the vacuum advance to manifold vacuum, it indicates your mechanical curve is wacko. Hooking the vac advance to manifold vacuum basically causes it to work opposite to the way it was designed.
 
If a motor is running on the rich side at idle more advance from the full time vaccum will help with burning the fuel.


Chuck
 
C130 Chief said:
If you run better hooking the vacuum advance to manifold vacuum, it indicates your mechanical curve is wacko. Hooking the vac advance to manifold vacuum basically causes it to work opposite to the way it was designed.
Click to expand...

Interesting, no vac advance now and it runs well. Maybe it was too rich at the time like 340 mentioned. :hockey:
 
As I recall the directions are very clear about which port it is supposed to be connected to.
 
I am going to try both sides for the heck of it. Ever since I replaced my distributor with a FBO recurve, at high speed to the floor I get detonation clatter. I may put my Mopar performance curved distributor back in just to confirm what the cause is. If it clatters with either distributor I am replacing wires next. Then remove the Champoin 9s and put in 11s.
 
If it clatters with more than 1/2 throttle, you are running too much mechanical advance, way too hot plugs, crappy gas, burning oil, or too rich a mixture. (retard you initial timing about 3 degrees or buy premium).

Too much vacuum advance will cause a light throttle clatter (ping) which you will be able to totally "step through" by 1/2 throttle.

In either case, the vacuum advance is totally out of play by 1/2 throttle.
 
The FBO distributor is 18* initial, initial + mechanical 34* and 10* vacuum. You have me thinking, the gas tank is half full with last fall's gas with Sta-bil fuel additive. I think I will top off the tank and change to Champion 11s. Thanks for the suggestions.
 
K3522:

If your getting detonation then we need to go over your specs again. That distributor is designed to run with the vacuum line connected to CONSTANT manifold vacuum, as they should be on any Performance application.

Detonation is caused by excessive heat in the chamber, are you running out of fuel causing to lean out, is the compression higher than we thought?

Somethings going on and we need to correct it.

Call me next week and we'll try and figure out what's going on. Send me a picture of the ground stap on the plugs so i can try and determine what's happening in the combustion chamber.

So 30% of the cars at the show new what they were doing the rest were guessing and didn't have a clue as to how the advance cannister works.

I have seen so many so called distributor experts and Companies publish the wrong information on this on going debate over which port, it's not rocket science. Performance applications alway's get connected to Constant, some stock and emissions vehicles go to ported. If it doesn't run right on constant then get the distributor curved correctly, your bandaiding a lousey mechanical curve with the vacuum can.
 
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