NHRA ACCEPETD AFTER MARKET CRANKSHAFTS
 

Can anyone guide me to the list of accepted aftermarket cranks?????

Crower is the only company that has a small block Chevy crank that has been in use for some time. It has a factory part number too.

http://www.crower.com/pdf/173-188.pdf

They are under the "Stock Plus" and "Pure Stock" names.

Raw GM crank forgings are shipped directly from
GM?s foundry to Crower. Stock GM part number is
forged into the counterweight. Features include lightening
holes and O.D. trimming that reduces weight
by 4 to 5 lbs under stock. Crower race-prep includes
1⁄8 radii and Crower heat-treat. Thorough magna-flux
inspection, chamfered oil holes, end-to-end index
check and polishing come standard. Crower even
straightens them so you don?t have to. Complete
stock legal engine kits also available.
WEIGHT: 51 lbs (4 to 5 lbs under stock GM weight

This is the "Stock Plus" crankshaft. Why would NHRA allow "lightening
holes and O.D. trimming that reduces weight
by 4 to 5 lbs under stock"?
Is there a limit to OD trimming? If OD trimming why not all the other mods in the other series (eliminate center CW, profile milling, wing contour, etc.)?

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1970 AMC AMX 390
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