Originally Posted by Whitelightning
With a Model A engine, the main bearings would have to be poured and then line bored in the block wouldn't they?

Yes, that's right. One of the oldtime Ford service manuals I've got describes "burning in" the main bearings, clamping a hard steel straight bar up in the main bearing bores and turning it with a big electric motor WITH NO LUBRICANT! "When all the bearings are smoking well, stop the machine, insert the crankshaft and scrape the bearings to a perfect fit". How's that for a challenging way to fit bearings? Fortunately, I've got a friend with a portable line-bore rig that roughs-in the bearing diameter close enough to drop the crank in and do the final bearing scraping by hand using Prussian Blue. Once it's a good fit with no high spots, the bearing caps are shimmed for the correct oil clearance, usually .0015"-.002".
Jerry


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