The stock HEI distributor out of my '75 Olds 455 appears to be in good condition: the drive gear isn't badly worn and the shaft spins freely with no funny noises. The shaft has no side play, but it does have about 3/32 of vertical play. The engine had around 100,000 miles on it; I'm rebuilding it for street use in my '70 Cutlass.

My original plan was to get an upgrade kit (PerTronix D8010) and reuse the distributor core, but that vertical play and the 100k miles concern me. I couldn't find any specs in the service manual on shaft end play - does anyone have some experience as to how much vertical play is acceptable (i.e. no adverse effect on timing)? And with 100k miles already on it, is it nearing the end of its useful life?

I'm not against buying a new distributor (PerTronix D1100), but I'd hate to discard a serviceable one.

 

Why buy a new distributor if the one you have works fine? Someone might have specs on distributor shaft end play. I thought there was a recent post where someone asked about that for their 394 distributor...

 

I see now that there was. I searched for "hei distributor" and didn't find it, searching for "distributor" did. Sorry for not being thorough.

Any input on whether 100k miles of use should be of concern would still be appreciated.

 

Not at all. I just couldn't remember if there had been a post or not. If someone mentioned the acceptable end play for a 394 distributor it could be different for a 455 HEI distributor.

If I were in your shoes I would continue to run the old distributor with a new cap and rotor. 100k miles isn't that many for our cars. If you get poor performance then consider replacing the distributor.

 

Keep an eye on the little posts that the weights sit on. They probably need bushings. If you don't bush them, the metal on metal contact will eventually saw the posts off.

 

HEI dizzys are easy to rebuild. Shaft end play is not critical on the Olds. Because it spins backwards, the rotor is pulled down on the housing, closing any gap. With that being said, I still wouldn't run with that much play. Off the top of my head, I can't think of a good number, maybe .010"-.030"?

Pickups and modules can be bought from NAPA. Or if you want a rev limiter you can install the HEI upgrade kit from MSD. If the stock Delco module still works fine, you should use that.

 

Not sure, but think so, HEI dizzy in Chevs are very reputable and dependable. I do beleive its normal to have quite a bit of end play. Maybe not in an Olds though. At any rate, whether it needs a rebuild or not is up to you, but I think I would stick with the HEI dizzy and not upgrade. It maybe end being a lateral upgrade anyway which is not an upgrade.

 

What are your plans for the car?

If your planning on running low 10's or faster at the track, go with an expensive unit. If it's a street car, street/strip car get an OE HEI from the parts store.

The only differecne with the dis's that cost $300, $400 is to impress your friends when you open the hood.

Note: My friend who has a dragster powered by a 500 ci Chyrsler big block, is running an OE points type dis. Car runs low 8's