Can't get distributor to lock down.

[grubsster]

I am having a fun issue. I have installed many distributors with no issues. I had my engine rebuilt a few years back and have constantly had timing issues. I thought it was an internal distributor problem and chased that for a while, then purchased a GM branded HEI from Summit. Dropped it in and have been driving it but still having issues. The other day while replacing plug wires I bumped the distributor with my hand causing it to move. No matter how much I tightened the hold down it still moved. Bought a fancy Edelbrock hold down with a stud and still moved. Bought the the moroso shim kit, removed the distributor and checked to see how much gap between the base of the distributor and the intake which was about .025. Installed the thick shim from the kit which checked about .065 and the gasket. Also got an OEM hold down from the salvage yard, used a stud so I would know the bolt is not bottoming out. Snugged up real good, let it run about 10 minutes after timing blipped the throttle and sure enough it rotated. I have not tried what another member on here did, which was to tap his oil pump shaft and his seated, which I will try tomorrow. I have pulled my 3 remaining hairs out. Any help would be appreciated.

Engine is a 283 with vortec heads and Edelbrock intake built by Boyettes machine shop in raleigh, a very reputable place.

[geezer#99]

I saw a clamp like this one once. Used on an off-road buggy. Under heavy vibrations the distributor wouldn’t stay in place.
Likely easy to make one.




https://www.connollymarine.com/Chevr.../all-27500.htm

[grubsster]

Thanks. That certainly looks like it would hold it. I'm just concerned I'm putting downward pressure on the oil pump. Other than the oil pump which rotates easy enough there's no real load on the distributor.

[The Rocknrod]

Originally Posted by geezer#99

I saw a clamp like this one once. Used on an off-road buggy. Under heavy vibrations the distributor wouldn’t stay in place.
Likely easy to make one.

https://www.connollymarine.com/Chevr.../all-27500.htm

https://pitstopusa.com/c-132723-igni...old-downs.html

[cadillac_al]

There must not be much downward pressure on the oil pump if it still turns. It must not be sitting tight on the manifold. I think I would try a double gasket to see if it tightens it up. I wonder if the heads and intake have been re-surfaced.

[grubsster]

Originally Posted by cadillac_al

There must not be much downward pressure on the oil pump if it still turns. It must not be sitting tight on the manifold. I think I would try a double gasket to see if it tightens it up. I wonder if the heads and intake have been re-surfaced.

Thanks for the reply. I agree because I've driven the truck for a while now but always chasing this timing issue. I tried the moroso nylon spacers with no luck.

I checked using my msd street fire distributor last night and without a gasket or spacers stands about ..035 taller than the intake. Seems the spacers and gasket installed would have compensated. The engine was completely redone and yes the block was decked .010 and has vortec heads. I called the engine shop and they said I should just need the spacer. I did try what another member on here did which was tap the intermediate shaft to make sure it's seated with no luck. I have also tried multiple hold downs but none of the extreme ones like geezer or rocknrod posted. Can't believe my little 283 would need something that extreme but I'm close to buying one.

Still looking for help...thanks everyone.

[geezer#99]

Got to thinking and remembered a similar problem you have.
Found the slot in the pump that the distributor shaft slides into had a small burr in it. Held the collar up enough it wouldn’t tighten down.
Had to reshape the tang a bit so it slid in better.
You could check that.

[grubsster]

Originally Posted by geezer#99

Got to thinking and remembered a similar problem you have.
Found the slot in the pump that the distributor shaft slides into had a small burr in it. Held the collar up enough it wouldn’t tighten down.
Had to reshape the tang a bit so it slid in better.
You could check that.

Thanks. The intermediate shaft to the pump or to the distributor?

[grubsster]

Does anyone have a idea as to how a regular HEI gap to the intake would be on a stock engine? Is there a gap or, does the distributor sit flush on the intake with no gasket?

[The Rocknrod]

I think he means oil pump.

[grubsster]

Originally Posted by The Rocknrod

I think he means oil pump.

Thanks, I'm hoping I don't need to take the pan off but I'm almost there... I'm going to call the engine builder again today.

[geezer#99]

Originally Posted by The Rocknrod

I think he means oil pump.

I did, but not wanting to pull the pump out I ground a little on the distributor shaft instead.

[grubsster]

Well folks I am officially at a loss. Pulled the oil pump and it was the correct shaft. All the pieces go together as they should, shaft to pump, distributor to shaft. Put the distributor in with no shaft and still won't lock down with a gasket and a spacer. I'm truly stuck...

[burnin oil]

Could be the driveshaft is to long. I have only had that problem on 400sb though.

[grubsster]

Originally Posted by burnin oil

Could be the driveshaft is to long. I have only had that problem on 400sb though.

Called the engine shop. A few years back some of the companies like Moroso were shipping BBC intermediate shafts in SBC packaging. They said maybe they missed one. Told me to pack the bottom of the distributor with grease and install it with the shims and the gasket, if it pushed all the grease out odds are its the BBC shaft which is approximately .500 inch longer. Sure enough all the grease came out. Pulling the pan later today... I'll post a picture. Thanks everyone.

[grubsster]

Picture of distributor shaft. That is with the 2 thick nylon shims about .090 and gasket installed.

[cadillac_al]

I'd be giving that intake manifold the side eye. Something must be out of spec with that. Maybe the old 283 has been decked more than once?

[grubsster]

Originally Posted by cadillac_al

I'd be giving that intake manifold the side eye. Something must be out of spec with that. Maybe the old 283 has been decked more than once?

Thanks. I honestly have no idea as far as whether it was worked before or not. So would I add more shims? How does one know if the gear is in the cam correctly? I have no out of the ordinary wear on the distributor gear.

[cadillac_al]

I don't think that gear clearance is going to make much difference on the intake mounting part. If anything it would be best to have no shims in there with the problem you are having. When you drop the dist in place, how much of a gap do you have between the intake surface and the distributor sealing surface? If the gap is big, something is out of spec, I would fill the gap with nylon washers and drive it.

[grubsster]

Originally Posted by cadillac_al

I don't think that gear clearance is going to make much difference on the intake mounting part. If anything it would be best to have no shims in there with the problem you are having. When you drop the dist in place, how much of a gap do you have between the intake surface and the distributor sealing surface? If the gap is big, something is out of spec, I would fill the gap with nylon washers and drive it.

I really appreciate the time all of you have put into trying to help me solve this. I like things to work as they should. The gap when installed is only about .030, with no oil pump shaft, so I keep thinking it should lock down with a .060 spacer and gasket. But cadillac you are right, I could throw the shims and a gasket in, buy one of the clamps that geezer and rocknrod mentioned and probably drive it. I may pull the motor and take it back to the builder. Honestly not hard to take out and put in, a day each way. Whatever I do, I will post back so that if anyone else chases their tail like I am right now, hopefully, this thread will help. If anyone has any other ideas though, I'm still all ears...

[cadillac_al]

What kind of intake is it? Is it new?

[crossfire84]

Don’t you have an other distributor to drop in and check if it bolts down? If so I would measure both to see what the difference is, hope this helps.

[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.

[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.

[geezer#99]

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