Distributor gear change

[SkylinePCG]

Little something inexperienced this morning, and I’m curious if this is an anomaly or not.

I’m switching distributors, both oem Motorcrafts as far as I can tell. The gears appear identical, feel the same, dimensions etc.

But when I went to to put gear #1 (that’s been run in my motor) on shaft#2, the pin hole didn’t line up. I tried removing it and rotating 180 degrees, no dice.

I ended up putting the gear#2 back on distributor #2, with the plan right now of just running it. Being another oem gear, what are the chances it’s going to give me problems since it’s not the original “matched” gear?

As an aside, distributor #2 is part of an EFI kit with timing control. I’m sure I could weld the shaft of the original distributor but I’ve got a lot on my plate and I’m trying to avoid extra projects.

[toothofwar]

I ran into a similar problem with my tbi install. The difference with mine was I didn't know better and left the new gear in the new distributor. Within minutes my cam gear was shredded. After discussing this on here, I found out that matched sets is really the only safe way to go. I don't know how deep you would like to go, but if you decide to change your can gear, I'd also look at the cam timing gear oil passage while you in there. It's nice to verify everything is getting plenty of oil, because dry distributor gears are a bad deal also.

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[SkylinePCG]

Was your replacement distributor a modded oem or an aftermarket? If mine were aftermarket (anyone’s) I wouldn’t entertain introducing its gear to my cam gear.

But being one of AMCs own...

[toothofwar]

It was unfortunately an aftermarket. But you live, you learn.

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[weeegoneeer]

I was able to put a new MSD distributor gear and used the old cam gear, but didn't know the potential issues and would not do it again.

If you buy a new set, get the MSD - it's pricey but they work.

Also, the dizzy gear only has the hole drilled in one side - you put in on the shaft and drill through to the other side. Prevents alignment issues.

[SkylinePCG]

Both of mine are previously used, so both have holes all the way through. May have happened 38 years ago in the factory, or maybe right befor I got them.

[derf]

From what I can gather, the alignment hole changed slightly at least once over the years. I have no idea when the change over happened, or why they did it. But the gears from early to late won't interchange. And you don't want to waste time using one distributor gear without it's matched cam gear. They will shred each other in a matter of minutes.

While they're expensive, the MSD gears have a good reputation. I installed a pair in my engine and they are great.

https://www.summitracing.com/parts/msd- ... can-motors
https://www.summitracing.com/parts/msd- ... can-motors

And the cam gear, as stated above, is set up to be universal. You install it, line up the single hole with one side, then drill out the other side, then put the pin in.

[SkylinePCG]

Any distinguishable difference between the gears that you’re aware of? And what is considered early vs. late?

[derf]

Any distinguishable difference between the gears that you’re aware of? And what is considered early vs. late?

The hole is slightly off between the two.

Early came before late.