When you have a rebore and regrind
Discussion
When I fitted a big bore piston to my bike, all those years ago, I took the new piston to the machine shop and they bored the barrel as appropriate. Is this still the case for car engines or do they know what the bore originally was and add 30 thou or what ever oversize your pistons are? What about a crank? Do they fit the new oversized shells, measure it and then regrind to fit? I've rebuilt car enignes before but always had the pistons and shells etc supplied by the machine shop so I don't know how they knew which size to bore / grind to.
Typically a machine shop will know what size to grind and lap a crank to based on the bearing manufacturer's data. The same goes for the pistons.
If you are building a highly optimised engine, for example a production type engine with few or mods allowed, the pistons would be measured, and the block would be honed with a deck plate to ensure everything was as good as it could possibly be.
The second adds a lot of expense and little gain so it is rarely done.
If you are building a highly optimised engine, for example a production type engine with few or mods allowed, the pistons would be measured, and the block would be honed with a deck plate to ensure everything was as good as it could possibly be.
The second adds a lot of expense and little gain so it is rarely done.
I would always supply all the bits and define the clearances I want, not just absolute sizes. Otherwise you're relying on their measuring stick being accurate enough, and also tolerances stacking up. Pumaracings approach is good - be anal about everything, otherwise you just end up having to do it again.
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