Locking Out Advance

[Mark Yacavone]

Turn the damper until the rotor starts to move..then turn it the other way until it moves again. .See how many degrees of slop you have in the chain and other clearances.
You DID say it was Pontiac, right ? LOL

When I had my G/SA car. I used to take the stock HEI unit and weld up half the advance slot, then use the lightest spring. The car always started well, and total timing would be in around 1500. Simple modification, cheap, and very effective. 455's don't need a bunch of timing anyway.

[Ed Wright]

Back when we used points ( I still had brown hair, and all of it) I used no springs. Start it, small whack of the throttle and it was at full advance. Drag of points pulled it back at start up.

[FSA1673]

I already locked out the vacuum advance when I built the car and cut off the canister. But that is a good idea if I still had it, very clever.

I used to run mechanical advance in the ditributor with light springs but I installed a MSD digital 6 plus box and wanted to try the timing locked out, to see if there was any performance advantage, and then later try the high gear timing retard. Box has a 20 degree start retard function so starting should not be an issue with 36 degrees

I will check the slack in the chain but I do not think there is much if any there. Will see tonight.

Will buying and MSD distributor fix all this? I liked the idea of the HEI with the terminals further apart rather than the MSD unit which are closer. But it is not firing properly with the rotor being out of phase.

Combo is 1971 Pontiac 455 HO if that makes any difference.

[R. Thorne]

Another option, fabricate a bracket for a threaded rod, bend rod to attach to the advance plate and mount to the original mounting holes for the vacuum advance, adjust for proper phase as Ed suggested and double nut it in position. Ron.

[Mark Markow]

Originally Posted by Mark Yacavone

In my way of thinking , you would want to fix it in the middle of travel, seeing the vacuum advance would swing the arc across the lug in the cap, depending on degrees of advance.

There is actually a GM factory fixed advance tab made for big block, governor equipped trucks..I don't know if you can buy it separate.

Sean, turn up the heat!

bingo mark has it right . if you are still triggering with the pick-up in the dist. and not a crank trigger . mid way is close you need to be sure the roter is phased to the cap when the reluctor post lines up to the trigger.