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 Posted: 07-20-2017 04:44 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 572
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 Many years ago, comments on this forum by JH racers who converted the 907 engine to run Chrysler 318 V8 main bearing shells. The idea was that for racers who rebuild the engine often, the savings on the dirt cheap Chrysler bearing shells compared to expensive Lotus shells quickly offset the initial machining costs and then became a significant on-going cost savings.

The +0.015" oversize bearing shells are no longer available from Lotus or JH sources. Vandervell, the original manufacturer, stopped making the Lotus OEM shells many years ago. Then JAE stepped-up, developed an aftermarket source, and also supplied bearing shells to other JH & Lotus suppliers. Now that source has dried up as well, and JAE's in-stock inventory is no longer insufficient to put together one complete set of +0.015" bearing shells. Owners of 9XX engines with oversize main bearing bores can no longer get bearings from any source. Perhaps a few lingering pieces getting dusty on a shelf somewhere, but not a steady, on-going supply.

As I recall, the first step to converting to Chrysler bearings was to align-bore the block assembly oversize. How much oversize? Was it (hopefully) +0.015" or more oversize? Are Chrysler 318 bearings a solution with a positive history?

Does anyone know the machining details? Preferably down to the 4-place decimal tolerances necessary to convert the block and main bearing panel assembly to accept Chrysler bearings?

Does anyone know how to reach any of those old racers who ran Chrysler bearing shells in their 907 engines? Any leads would be appreciated.

This affects all 9XX owners, JH and Lotus (907, 910, 911, 912, 920), whose block assemblies have been bored +0.015" over-size. In some cases, the blocks were bored oversize at the factory, so this can also affect 'virgin' engines. If a block was bored over-size at the factory, then +15 was stamped on the bottom of the Main Bearing Panel's 4th or 5th bearing web.

I've also posted this message over on the JensenCars mailing list on GoogleGroups. I think it's in the collective's best interests to figure out a workable solution.

Thanks & Regards,
Tim Engel

Last edited on 07-21-2017 04:10 pm by Esprit2