New Cast "Steel" Stroker Cranks Arrived: Initial Inspection

[RobMcQuarie]

We had a chance to check a second crank and it was even better. Mains showed .0005 from smallest to largest main jounal, with only .0002 taper. Rods showed .0003 size variance and up to .0003 taper. Stroke was right on with 1.249-4.250. Actually pretty darn good. I don't see many crank grinders that can hold their tolerances any better. It is generally accepted that "stock" grinds are acceptable with + or - .0003 and a high performance/high tolerance grind is held to .0002 variance. This is what we see with the high dollar billet cranks, but it is rare with your typical crank grinders out there.

I did check w/Scat, and oversize cranks are not available, so if you are looking for an absolute spot on grind, you may have to grind .010 under. But, don't expect that just any crank grinder will be able to do so.

We are going to be able to polish the "large" mains on the first crank to bring the sizing in pretty close. With only a two crank sample so far, I would advise checking closely, but you should be able to use these cranks as is. These cranks will be a nice addition to the FE builder's war chest.

NOTE: This whole discussion is based on the assumption that the block has been properly line honed, with new ARP hardware, and you are using Performance type high quality bearings. If not, your tolerances in the bearing housing bores will be off far enough that an accurately grond crank is a moot point. And that includes any block that the machinist has passed jugdement on as NOT needing a line hone. Rubbish, after 40 some years, EVERY performance block needs new hardware and a QUALITY line hone.

Rob