Vacuum Advance

[k7ujx1]

I will probably regret putting this information on this post, however I
think some one out there may benefit, if you would like to try it, or
experiment with it.

A few years ago we had quite a few people in the trade with there high
compression vehicles and with low grade gas pinging is always a problem.
One of the locals here in a speed shop is Seattle came up with a new
approach. Change out the Vacuum Advance one that moved less, there by you
are able to set your initial timing a little higher. I made the change
on two of my vehicles 71 Chev 400sb with 69 HC heads and 71 Riv 455 I
haven't done this to my GMC yet but when I get to that part of my project
I will be doing it also. Most of the V.As. move more then 16 degrees add
the mech advance
and it is way out of proportion for what we are trying to accomplish.
Like I said it works for me. These were both HEI

Gary Duvall WA.

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[gene]

I think you are right on. If you read:

http://www.california.com/~eagle/engine.html

"Recurving your distributor"

You will see the current recommendations for the GMC are
base = 8
VA = 10
flyweight = 18

for a total advance of about 35 at 2500 rpm.

gene

> I will probably regret putting this information on this post, however I
>think some one out there may benefit, if you would like to try it, or
>experiment with it.
>
>A few years ago we had quite a few people in the trade with there high
>compression vehicles and with low grade gas pinging is always a problem.
>One of the locals here in a speed shop is Seattle came up with a new
>approach. Change out the Vacuum Advance one that moved less, there by you
>are able to set your initial timing a little higher. I made the change
>on two of my vehicles 71 Chev 400sb with 69 HC heads and 71 Riv 455 I
>haven't done this to my GMC yet but when I get to that part of my project
>I will be doing it also. Most of the V.As. move more then 16 degrees add
>the mech advance
> and it is way out of proportion for what we are trying to accomplish.
>Like I said it works for me. These were both HEI
>
>Gary Duvall WA.
>
>
>________________________________________________________________
>YOU'RE PAYING TOO MUCH FOR THE INTERNET!
>Juno now offers FREE Internet Access!
>Try it today - there's no risk! For your FREE software, visit:
>http://dl.www.juno.com/get/tagj.
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/