AV7 crank shimming

Douglas Mackinnon /

So I’ve been rehabbing an old Moby with its original AV7. The engine’s bottom end was completely stuck. Yesterday, I started reassembling the case. I purchased new bearings, seals and an Airsal stuffed crank.

I test fit everything using plastic mock-up bearings and found there’s about .80mm of side play with the cases at spec torque w/ gasket installed. You can rattle it around.

That’s quite a bit considering the shop manual says “1/10mm” or 0.1mm. There were no factory shims and the original rusty bearing/ crank setup measures out dead nuts same across outer bearing edges.

I can only assume it was as loose previously. I purchased 2 of every shim size available from Treatland. I should be able to get it a lot closer.

I’m Just curious, if anybody else has ran into this?

From what I’ve read, shims are not too common to find in one of these engines, let alone so much.

Re: AV7 crank shimming

Totally normal JBOT /

Shim it if you like, unless you’re really spinning it you’ll probably never notice a difference.

Just leave a bit of room for heat expansion

Re: AV7 crank shimming

0.1mm sounds a little tight, maybe not for a stock setup but once you start spinning more rpms itll want some more wiggle room. I'd shoot for 0.3-0.4mm.

Re: AV7 crank shimming

Richard Eberline /

Plastic mock up bearings are for port timing and squish.

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