Distributor gear alignment

[ken-r-mer]

While swapping out to a dual point mechanical advance setup I noticed, both, the original and new mallory distributor gears extend about 3/16" past center when set into the cover when its off the block.

Will this be corrected when the distributor tab sits on the block seat for lock down?

I shimmed and cut the Mallory shaft to match the distance from the underside of the distributor case tab (used to secure the distributor to the block) to the end of the shaft.

[rotorwrench]

There are several different covers for the 8BA family of engines. The first was the a cast iron type that used the original P/N 7RA-12127-C and the later 8BA-12127 distributors and their gears were pretty much flush mounted to the bottom of the distributor shaft. The second one was the aluminum type that was used with the P/N 0BA-12127 distributor that had a pilot bore in the lower recess of the housing for the extended shaft that protruded a bit below the distributor gear acting as a pilot bearing for more support. I've seen other variations on these but they were manufactured for six years plus so there may have been several suppliers of these covers.

[51 MERC-CT]

On a stock distibutor the dim. from the mounting pad (that clamps to the head) to the end of the gear should be 8.00"±.
This dim. should hold true no matter what distributor you have.

[BUBBAS IGNITION]

51 merc is right on with th eight inch rule.

Heres a couple pics of a mallory and one of our chevrolet conversion.
As you can see they dont fit on the centerline. I think all helical gears run off center...

[51 MERC-CT]

This is a shot of stock location when clamped to head.

[Walt Dupont--Me.]

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I think you'll find when the dist is bolted down on the head where it belongs the gear will be pretty well centered. I've made some of those Chevy dist conversions ( not as good as Babba's ) and always made them to clamp down so the gears were about centered. Walt

[51 MERC-CT]

Originally Posted by ken-r-mer

While swapping out to a dual point mechanical advance setup I noticed, both, the original and new mallory distributor gears extend about 3/16" past center when set into the cover when its off the block.

Will this be corrected when the distributor tab sits on the block seat for lock down?

I shimmed and cut the Mallory shaft to match the distance from the underside of the distributor case tab (used to secure the distributor to the block) to the end of the shaft.

I suppose that you can conclude that so long as the gears mesh and the distributor gear does not come in contact with the timing cover 3/16" offset would be OK.

[BUBBAS IGNITION]

Originally Posted by 51 MERC-CT

I suppose that you can conclude that so long as the gears mesh and the distributor gear does not come in contact with the timing cover 3/16" offset would be OK.

They seem to be pretty forgiving. Also seems as if the aftermarket heads have some variations in regards to pad height as well.
The good news is that the distributor doesnt drive any acc etc like a oil pump or something. Very little load on the drive if any..