Thread: ARP Rod bolts
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spuggy spuggy is offline
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Join Date: Jul 2003
Location: Perfidious Albion
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Quote:
Originally Posted by AlfonsoR View Post
I haven't bought any rod bolts so I don't know the stretch spec for sure, but I read in one thread the spec was 11.5-12 mils (1 mil = 0.001"). From what I understand, the accuracy of most dial calipers (0-6 inch) is +/- 1 mil. I don't think I would want to be using a dial caliper if that's the case.

Plus, not only are you fighting the case to get the tool in there, the micrometer should provide more consistent, repeatable readings.
For a 930 (and presumably the 3.2, which has the same crank, rods & bolts), ARP spec their 204-6005 rod bolts and give the required stretch over each bolt's individual "at-rest" length as .25-.27mm. Which I make 0.0098" to 0.0106".

So you're looking for ~10 thou stretch, ideally just slightly on the fat side of 1/100". Getting repeatable readings within a couple of tenths of a thou with a good vernier mike can be tough enough, so yeah, a caliper doesn't seem like the ideal tool for that job.
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Old 12-30-2010, 09:52 AM
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