Is the a max limit on rod bearing shims in a banger engine ? I've got reconditioned rods and a new Burlington Crankshaft and need more shim than what came in the rods to get proper clearance..
Most of the time I believe the new rods come undersize babbet for cranks that are undersize. If you happen to have a standard crank I would size the new rod to the crank, not add shims to make the Rod hole larger. At any rate you need to fit each rod to it's Crank throw. All of them wear differently.
The way we do it is fit a few shims....maybe 0.003"-0.005" total. Then if it's still too tight use a bearing scraper on the tight bits if it's only tight by a few thou., other wise it's a rotary mill job....still leave a shim in there so someone can take one out to take up wear in the big-ends in 30yrs time.....
Didn't your new rods come with multiple shims already installed? The ones I've delt with started with .020 stack installed and the hole bored round. If you start adding shims you'll end up with an egg shaped hole and still need to scrape the sides to get back to round. Scraping the Babbet to size is common. With all new parts I'd start by getting true I.D. size of each rod and make sure they are in fact round then measure each rod throw of the crank so you know what's in front of you to do. I don't believe any new rods come ready to just install as even to a new crank. It not like buying a new crank and rods with inserts that fit as is.
The new rods came with a shim stack already in them but still not enough clearance, I'll have them sized to the new crank. The rods measure round but are a couple thousands shy to make proper clearance for the journals..
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