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Discussion Starter · #1 ·
Hi group,
Regarding the vacuum advance canister pull pin on *stock HEI distributors, I read a couple places that the pull pin originally came with a small piece of rubber tube that limited some of the total advance pull from the vacuum canister.
This rubber would inevitably deteriorate and crumble away and the advance would increase greatly and cause problems.
I cant see any rubber piece on my distributor.
Can someone please share a detailed photo?
Thank you
 

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Keep in mind if the vacuum pin never had a sleeve over it, adding one will change the initial position of the pick up to the reluctor by that amount the pin is away from bottom out in slot. Changing that also advances the position of spark to the distributor cap contact. If you want to limit degrees of vacuum advance a preferred way is to limit the stop position at the far end of travel. As seen in photo with a sharpe “L” shape metal press fit & Loctite in end of slot. Use what ever thickness desired to limit travel of pin in slot. I shot for 7 degrees total vacuum advance. And if memory is correct that is about .100” thick.
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If you want an easy way to limit the amount of vacuum advance timing on a "GM style" HEI, just install an MSD 84281 vacuum advance stop plate.

Below is an image of the MSD stop plate that I installed on my HEI (red arrow).
This type of stop plate is very simple to install and adjust on an HEI.
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