Distributor Gear problem

I started disassembling my spare sbc engine today that has 500 runs and when I removed the MSD Billet distributor that was installed new I couldn’t believe that the gear teeth were almost worn away.

I noticed that it appears the cam gear doesn’t engage the very top of the distributor gear either.

Why is this happening and what should I look at doing to keep this from occurring again?

Any chance the distributor gear is bottoming on the oil pump drive shaft? It should have clearance between the 2.

quote:

Originally posted by Eman:
Any chance the distributor gear is bottoming on the oil pump drive shaft? It should have clearance between the 2.

The distributor drops all the way in and the fixed collar is tight against the manifold with thin gasket in-between.

Distributor endplay?

Locked out?

Camshaft endplay?

Weight oil?

High volume oil pump?

Slip collar? If no might need one.

Post photo entire distributor.

quote:

Originally posted by Mike Rietow:
Distributor endplay? Locked out? Camshaft endplay? Weight oil? High volume oil pump? Slip collar? If no might need one.

MSD 85551 Pro-Billet distributor with fixed collar and locked out. Melling 10% higher volume than standard pump. 20w50 BP.

quote:

Originally posted by markemark:

quote:

Originally posted by Mike Rietow:
Distributor endplay? Locked out? Camshaft endplay? Weight oil? High volume oil pump? Slip collar? If no might need one.

MSD 85551 Pro-Billet distributor with fixed collar and locked out. Melling 10% higher volume than standard pump. 20w50 BP.

Machine off the collar, add a slip collar. Measure for depth as it is vs how far it falls no collar / slip collar.

Post a photo of dist. Does it have o-rings?

Correct depth is drop it no collar, lift it 025 w/gasket.

https://images.holley.com/583x/85551_0118305.jpg

O-rings Not installed. Dart SHP sbc

quote:

Originally posted by markemark:
https://images.holley.com/583x/85551_0118305.jpg

O-rings Not installed.

If it has grooves for o-rings, run the top o-ring only.

I have the same distributor. Why do you say leave off the lower o ring?

quote:

Originally posted by BG7X77:
I have the same distributor. Why do you say leave off the lower o ring?

Oil the gear. If the gear looks good, leave it.

No reason to leave the lower o-ring off. The housing should have a small hole vertically to a hole between the o-rings that will help oil the gear.

Looks like the distributor isn’t dropping in enough. Just had a friend with the same problem, his machinist ground the old collar off the dist and put a slip collar on it.

Probably needs a slip collar and I think they have oversize bronze gears if that does not fix it. Appears that it is now lot enough.

I bet it is just barely catching oil pump drive to.
I use a slip collar and set it up where it is bottomed out with no gasket, tighten down collar and then remove it and put a gasket on there for the clearance I need to keep it from bottoming out and hurting your pump.

If the engine is on a stand or the trans is out,pull the lifter galley plug in the back of the block to see that the area between the orings is centered, or measure with a pair of calipers.
Sometimes the bottom of the gear needs to be machined to clear the block.
Sometimes the drive ends up too long becaust of machining tolerance on the oil pump,drive, and dist shaft.
The void between the orings (transfer passage) needs to be centered, the gear should also be centered, the distributor should drop in and touch the manifold with no gasket, then add 1 gasket to set the clearance.
You also need to check the oil pump to make sure the gears have not been eating into the cover.

Honestly it appears to have about 90% or more engagement. That should be more than enough. Was the cam new when you put the engine together? The cam gear may need to be deburred. I have seen some really rough. Also knowing so many things are off shored now I would be more inclined to blame rough cam gear or dust. gear material than engagement.

Look into the Morel distributor gears for American made gears.

This engine is a Dart SHP that was built all new 6 yrs ago by a shop that installed the distributor, ran it for four years 500 runs and has been sitting as my spare the last two years. The cam was new from Cam Motion and the then new oil pump is a Melling 10552.

I’m removing the intake and heads now to go back to the guy that ported them for freshening. I’m having the short block rebuilt by a different shop that is closer to me and dropping it off next month.

I’m taking this damaged distributor gear with me to show them so they can inspect the cam and installation. I’m having the oil pump replaced with the standard volume Melling ST model during rebuild.

The engine in the car now which is a Little M has the exact same internals as the SHP, has the same nonadjustable collar distributor also. In spring when I get the car back out of the trailer I’m going to remove that distributor as well.

I’m switching ignition controls next spring and need a distributor with dual Hall Effect outputs and am looking at the 2376MSD as the replacement. This is a BBC tall deck model distributor with adjustable collar.

Curtis, I’ll look at the Morel gears also. Thanks Mike for the initial suggestions.

Looks like it might need to engage in the cam gear deeper.

This fall when I was taking the rocker arms off one of my engines I found some bronze in the corners of the heads. Figured it had to be from the gear so I pulled the distributor out and found a bit of wear on the gear. Gear has about 500 runs on it so it’ll get a new one. I imagine with how worn yours is you would have had a lot of bronze floating around, surprised you didn’t notice it sooner. When I cut the filter open as I do at every oil change I found more bronze in it.

I pulled the cam plug out and centered the gear on my last rebuild. It made an unbelievable difference. I also got rid of the HV pump and I've always run either 10-30 or straight 30. This is a 12:1 BBC 433 that only turns about 7k in the 1/8.

how high was oil pressure.
? just curious.i have had the issue before ,not sure what caused it or fixed.i am guessing it was a gear material issue or matching to cam material.one other idea is the machining on the cam as was mentioned above.