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I am building a mild 383 Chevy motor. I am using a scat cast crank and H beam rods. What is the necesssary rod to block clearance needed in such an application ? Is grinding results go to far is there a repair that can be made that is reasonable and effective. How much will a spinning assembly grow if at all under normal circumstances ?

Thank you,
John Johnson
Millville, CA

Hi John,

Generally speaking, you want to have at least .060" clearance between the Block and any moving component, in this case the H Beam rods. Depending on the brand and design of the rods you have you may not need to perform any clearancing. If you do, just use one rod and piston assembly without rings installed and work from cylinder to cylinder by installing the rod and piston and carefully rotating the crankshaft until the rod bolt touches the block. Make a outline of the area with a marker and move to the next cylinder. Once you have all of them marked use a die grinder with a 1/2" diameter carbide and carefully remove the needed material. Unless the cutter gets away from you I don't see why you should have any worries about "going to far". As for the assembly "growing" it depends on the parts used and the RPM attained. Generally, you will not have to worry about it.

Hope this helps,