ORIGINAL: downunder
ORIGINAL: Jim Thomerson
Cox engines don't need much break in because of the precision with which they are made. They are in fact little jewels.
What Jim said. I read the other day where someone said they were made to a tolerance of 25 millionths of an inch which is pretty much what I'd heard years ago. They had to do this because they were pumping out engines in the thousands every day and they couldn't afford to have anyone hand fitting pistons to cylinders or giving a final hand lap as Enya used to do. So any .049 piston would fit perfectly in any.049 cylinder. This can't even be done today on the much vaunted CNC machining with much larger engines where fits aren't as critical. Because of this precision Cox said a one minute rich run was all that was needed to finish settling in all the parts.