anyone have experiance with coated bearing (rod and main) and tolerances? should it be tighter or what? i'm at the point now where it's time for me to measure and stuff just not sure how much tolerance i should run. thanks, ron

 

I did some research on this, and if you're talking about the Tri-Armor bearings from Clevite, they claim the coating thickness is .0003", so it's nothing to worry about. The coating is supposed to last, and if it doesn't for some reason it won't significantly change your clearance. I haven't heard anything bad about them yet, but I really haven't heard much at all.

 

actually i'm talking about calico. i guess they actually grind the bearing down then add the coating so you can get within the gap you're looking for.

 

Bearing clearance depends on the diameter of the crankshaft main and rod journals, the main bearing bore dimension in the block and the bore size in the con rods. Some manufacturers grind their cranks on the low end of the tolerance range and even under that size. So you need to be careful with sizing of bearings.

No one "grinds" bearings before coating that I am aware of. I use Calico bearings and have found that I usually need to get two sets of mains, one std. and one X (.001" oversize) to get the main bearing clearance correct with a stock sized crankshaft - not one of the smaller aftermarket cranks. That is with the block align honed to the low end of the main bearing bore size range for max. bearing crush.

Steve

Steve

 

thanks steve.