Can't get distributor to lock down.

[geezer#99]

Originally Posted by MySons68C20

geezer#99, do you think it's possible it is bottoming out on the cam gear?

If the pump shaft were out out what else could it be?

Easy to check.
Remove the gear and see how the distributor sits.

[grubsster]

Originally Posted by geezer#99

What did you mean in post #20 about ‘no oil pump shaft’?

I had removed the oil pump and shaft to eliminate them as the culprit. I finally did get it to lock down using one of the heavy duty clamps like you and rocknrod had mentioned. I think I have too thick of a spacer now because my mechanical advance isn't working now. But that should be an easy fix. I may be almost done with this issue...

[geezer#99]

What did the engine builder do with the vapor canister in the lifter valley at the back near the distributor?
I’ve seen them hammered out of the way enough to interfere with the distributor shaft.

[grubsster]

Originally Posted by geezer#99

What did the engine builder do with the vapor canister in the lifter valley at the back near the distributor?
I’ve seen them hammered out of the way enough to interfere with the distributor shaft.

I honestly don't know but, the down draft tube connection is still there, so I think they just left it stock.

I get home around 2 a.m. from work so I'm going to go out to the garage and tinker with it when I get home. Hoping I can free up my advance and still get it to lock down... of course I can't fire it up again till daytime.

[mattfranklin]

Intake issue? -- Maybe it just needs a new tunnel ram. J/K.
Seriously, what a pain.

As long as the shaft isn't bottoming out and keeping the bottom of the dizzy flange from seating on the intake...

There aren't many things left. Surface roughness (on the intake, dizzy upper and lower flange surfaces, and clamp) and clamping force are what you need to keep it from twisting. Are any of the surfaces more shiny and polished (and oily) than normal? Rough cast surfaces can be pretty grippy compared to smooth machined or worn surfaces.

I remember an old engine once that was pretty each to move just by tapping the distributor diaphragm cannister back and forth. It had a really shiny top flange surface where the clamp was supposed to dig in, and I think the clamp was really smooth too, and it had a film of oil on it. Maybe you just have the perfect storm of all of these things adding up against you.

Good luck and keep us posted.

EDIT: Is the clamp right-side up? Are there sharp corners on the steel clamp to dig into the aluminum flange of the distributor?

EDIT2: Note sharp corners on stock clamp. https://www.summitracing.com/parts/n...make/chevrolet
I've seen some aftermarket clamps have rounded bumps to do the clamping. Nice for not scratching show-car polished billet distributors, but kind of lacking in the grip department.

EDIT3: Check the stars and comments on that Summit link. They guys were using the stock clamp with a stud to solve their problems.

Originally Posted by grubsster

Cadillac_al, yes it is a new edelbrock installed by the builder when they assembled the engine. I am growing more suspicious of the intake. I guess this is why I've been chasing the timing issue for so long.

Crossfire, thanks. Yes, I have tried multiple distributors and clamps. I even pulled one out of an old truck yesterday just to see if it would lock down. None have worked out.