Just wondering if I can turn down a 4.0 crank from 2.185" down to 2.1" so I can use Chevy rods? Will this compromise strength in a 7000 RPM race motor?
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Shouldn't
How do the 3.9 cranks hold up with their 2.0" rod journals?
If you use the 2.1 rods, make sure you use the ones with 3/8" bolts. The 7/16" ones are too wide.
I am not 100 % sure but I believe than you need to machine the rods narrower anyway.
Yep, .050, both sides and both ends.
My stroker crank has TVR sized rod journals (narrow) and the rod big end width is 19,4 mm ( just over 3/4"). They needed a bit more machining. Also the bearings had to be machined narrower.
Hi John, First off, you have verified all manner of components to get you max power at 7k rpm. ? If so, by all means, 2.100 journals. Don't assume taking .050" off each side of big end of rod will put end, in center of bore . Use bigger fillet on journals, if possible. If 3/8" bolts, use AP 2000.
What is your hp. level ? Don't expect your cast iron crank to live many happy racing miles, at hi hp. and rpm.
Good luck, Art.