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Discussion Starter · #1 ·
I just received a new RTR distributor from Summit. The instructions for the vacuum advance state that the screw inside the hose nipple will change the AMOUNT of advance. My experience with these adjustable vacuum advance distributors is that they only change the rate of advance, not the amount of advance. I have modified point and HEI distributors to limit the amount of vacuum advance, but that takes more than just turning the screw in the nipple. So are the instructions full of crap or do they actually have something different? Anyone have any experience with this distributor?
Thanks for any insight.
 

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Easy to limit the magnitude of the vacuum can by press fitting and Loctite a .098” aluminum stock formed at a sharp right angle (no form radius) in the window the rod stops in. This piece needs to fit tight with the forward edge. Custom file the aluminum thinner to allow a bit more advance if desired. Doing this about cuts the vacuum advance in half at .098”. I like about 7 or 8 degrees.
 

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Easy to limit the magnitude of the vacuum can by press fitting and Loctite a .098” aluminum stock formed at a sharp right angle (no form radius) in the window the rod stops in. This piece needs to fit tight with the forward edge. Custom file the aluminum thinner to allow a bit more advance if desired. Doing this about cuts the vacuum advance in half at .098”. I like about 7 or 8 degrees.
That for a stock vac can, thought most aftermarket adjustable have 10 deg? Cool trick, I saw an old post the other day when I was refreshing my memory on HEI mods, but they used a plate I think to limit movement(old post and pics where gone so just had words to go by).
 

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As an aside , I'm aware that many folks don't keep their vehicle long enough to change /service the distributor , I wonder how long parts will be available for these import / aftermarket units ? If you have a vacuum pump it would be pretty easy to check what the screw adjusts ....
 

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Discussion Starter · #6 ·
If you have a vacuum pump it would be pretty easy to check what the screw adjusts ....
I just use the engine for my distributor machine and vacuum pump. I will figure out what it does when I get it in the engine. I have to do a little cutting on the distributor notch in the firewall to get it in there. The darn thing is 1" taller than a points distributor. The notch was made for a points distributor and I had to take the rotor off to get it in.
 

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That for a stock vac can, thought most aftermarket adjustable have 10 deg? Cool trick, I saw an old post the other day when I was refreshing my memory on HEI mods, but they used a plate I think to limit movement(old post and pics where gone so just had words to go by).
True, I always use modified original parts vs aftermarket only because I feel the quality and accuracy are proven. But there are good aftermarket stuff too. Original vacuum cans are a type of part that definitely has a better proven record vs aftermarket IMHO. Advance rate to vacuum more consistent but just too much degrees for performance use. My preference is modified points distributor into HEI over aftermarket offerings too. Reason......original look, and cost $$$ of a quality aftermarket is too much.
 
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