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Discussion Starter #1
I’m running an adjustable vacuum advance can made by Accel and am wondering what exactly I’m adjusting when I turn the adjustment screw. I have tried to find a good description of this but haven’t been able to.

Neal :thumbsup:
 

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Halfway down this page are simple cross sections etc.

http://www.kendrick-auto.com/ignition.htm

Here is a hands on explination
http://www.73-87.com/7387garage/drivetrain/hei.htm

Another
http://www.highperformancepontiac.com/tech/vacuum_advance_tech/carburetor_modification.html

Here is Cranes PDF
http://www.cranecams.com/pdf/210g2.pdf

http://www.cranecams.com/pdf/Page607.pdf

A separate hand pump vacuum source with gauge works well for seeing when it activates and how far it goes. You need a dialback timing lite or degree tape for this.:D
 

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I’m running an adjustable vacuum advance can made by Accel and am wondering what exactly I’m adjusting when I turn the adjustment screw. I have tried to find a good description of this but haven’t been able to.

Neal :thumbsup:
I've only used a Mr Gasket but I think its the same.On the MrG you put the allen wrench in the nipple and tighten a spring that resists a diapram.This adjustment only changes the amount of vacuum it takes to move the diapram and advance the timing.That part works OK but I prefere the fixed cans.The thing you cant change(at least with the MrG)is the amount of timing built into the unit.Mine had 30 degrees in it !!! Way too much-I soldered a piece of metal in to limit the timing.Hope this helps if nothing else it will give you a bump.:thumbsup:
 

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The can itself I think is made by only one manufacturer but marketed and packaged by several different brands.

The Crane comes with a limiter plate to limit the amount as shown here and above. It is also available separately and is good for playing with.

http://www.cranecams.com/pdf/Page607.pdf
That bad boy is hard as hades to install with the dizzy installed. I tried and tried and never got it installed. I wound up going and picking up a fixed unit that was recommended by Lars.
 

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I found that using the hand vacuum pump with out the engine running and the cap off and then later with it running seems to work out best for me.
 

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Discussion Starter #7
thanks for all the help, I will read through the info in the liinks.


Neal :thumbsup:
 

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That bad boy is hard as hades to install with the dizzy installed. I tried and tried and never got it installed. I wound up going and picking up a fixed unit that was recommended by Lars.
:agree: The adjustableunits are crap. Read the Lars tune up "stickey". Select a fixed unit for your application. Toss the adjustable in the trash.:thumbsup:
 

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Or toss both of them in the trash and don't run one at all. you realy don't need it just follow the sticky and change the springs and dial it in,just one less vacume leak to worry about. :thumbsup:





Kevin
 

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Discussion Starter #10
Or toss both of them in the trash and don't run one at all. you realy don't need it just follow the sticky and change the springs and dial it in,just one less vacume leak to worry about. :thumbsup:





Kevin
I need the extra vacuum at idle, with this motor.

Neal :thumbsup:
 

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I need the extra vacuum at idle, with this motor.

Neal :thumbsup:
Oh,ok well i don't have any experience with the adjustable vacume advance,but from what ive read from the other poster's it sounds like when you adjust it that you are loosening or stiffening a spring inside the can that affects how much vacume is needed to move the internal diaphram, if that made any sense :laughing: Do you have a big cam in your motor?

Kevin
 

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Discussion Starter #12
Oh,ok well i don't have any experience with the adjustable vacume advance,but from what ive read from the other poster's it sounds like when you adjust it that you are loosening or stiffening a spring inside the can that affects how much vacume is needed to move the internal diaphram, if that made any sense :laughing: Do you have a big cam in your motor?

Kevin
Decent size solid roller, :thumbsup:
 

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Discussion Starter #14
What Dizzy are you running? What is your vacuum at idle?
10.5 hg at idle (1000 rpm) :thumbsup:

what is a dizzy? :laughing:
 

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Discussion Starter #16

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Discussion Starter #18
Go to Napa and buy an "AR-12" and an "AR-31." See which one works best for you, and return/save the other one. Your vacuum is kinda at the break.
Giving NAPA a call right now, thanks :thumbsup:
 
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