current distributor in my Skylark with the 455 is a HEI from a 76. Number is 1112985, does anyone know of how much advance was built into that distributor? Would like to get my car time properly or buy a different HEI.
Ryan, It would be in the 1976 Chassis Manual. Teambuick only has a 1975, but I'll post it here. Chances are 1976 are the same, but it might not be. There seems to be only one distributor for the 455 in 1975, but those are pretty good specs for an HEI, 14-18* at 4400 RPM. Hopefully yours is the same. Pretty easy to verify though, all you need is a timing light (preferably an advance one), and a set of light springs. Install the light springs in the distributor, plug the vacuum advance, and then set the total advance to what you want. Then shut the engine down, and put back the stock springs or the heaviest ones you can find, and check the initial timing. Idle the engine down as low as it will go without stalling when you check the initial advance. This and the heavy springs precludes the chance of there being any mechanical advance at idle speeds. Then just subtract, total-initial and you'll know what you have.
Thanks for the help. I saw your other thread on distributor specs but it didn’t go up to 76. As a matter of fact it didn’t have the 75 you posted above either.