"Pilot" hole on 392 crank

Discussion of the 331-354-392 HEMIs.

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Jacin
Posts: 5
Joined: Wed Aug 29, 2007 9:44 pm

"Pilot" hole on 392 crank

Post by Jacin »

I see some of the aftermarket trans kits use the factory pilot hole to center the converter and flexplate.

Seems like a mistake ot me since I'm under the impression that THAT hoel is not necessarily centered on the crank.

Anyone have any experience here???


Thanks
Powerflite
Posts: 26
Joined: Wed Oct 05, 2005 8:22 pm
Location: Los Angeles, CA

Post by Powerflite »

It is centered on the crank. It is used to center the manual transmission shaft with a bronze pilot bushing installed. How accurate is it centered? Accurate enough since all 392 cranks (to my knowledge) are actually drilled for the bushing. Accuracy would only be an issue on much later cranks where the hole is not necessarily drilled - just "as cast". Most kits I have seen center on the crank flange though, not the pilot hole.
Jacin
Posts: 5
Joined: Wed Aug 29, 2007 9:44 pm

392 Crank Hole

Post by Jacin »

Thanks for your reply. I'm not sure IF I was clear enough in my origional post. I don't mean the small diameter hole but rather the larger c'bore (if memory serves it's right around 2" (maybe 1.941") and about .200" deep.

I ask because I bought an aftermarket trans kit and they provided a bushing that is supposed to align everything. I noticed that MOST other kits ,as you mentioned, pilot on the crank flange OD - so it prompted me to measure mine. It was offcenter .005 (.010" TIR). When I asked the manufacturer of the kit they suggested I must have a "bastard" crank. So I went and measured another one I have - it's off quite a bit more.

Now keep in mind I am NOT talking about th ehole in which teh factory installed that sleeve bearing - I would expect that to be quite accurate.

I'm gonna check much more carefully on the next crank I get ready to use, but I was also wondering what others experience was on this topic. I have a couple more cranks to measure but they are packed away.

FWIW - I ended up machining a custom "offset" bushing that when installed in the proper clocked position will "fix" my problem. Kinda hokey I suppose but I wasn't prepared to yank the crank back out at this stage. Maybe next time.
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