jbeenz wrote:
well, two.
2. what have people paid to grind a stroker crrank.
1. What stroke does a small journal rod on a big crank give @
*std
*010
*020
roughly
1. Spiro (at St George Cranks) said when he did mine last year that he charges A$240 to grind the mains to next size under, and offset grind the crankpins/rod journals to std Cooper S size.
2. Your question is ambiguous, are you talking about offset grinding a std crank to -.010" or -.020", or grinding down a crank that is already at -.010" or -.020"??
anyway-
The std stroke of a 1275 was 81.33mm. In my case, the 12G1505 crank was std/std, and Spiro managed to offset grind it to 84.33mm, an increase of 3.0mm. This is with std size (1.625") I could have gone smaller, but why weaken it... it's only EN16.
Going .020" under std will give another .020" stroke, as taking .020" off the inside of the journal moves the crank throw out by .010", you double that figure to get the stroke change.
Obviously, if you start with a crank that's already undersized, you won't get quite as much stroke as I did.
Matt Read TheMiniMan did a couple once to -.080", got 86mm stroke approx but bearing shells that size are apparently rocking horse now.
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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
