Quote Originally Posted by Kevin C View Post
To get an accurate measurement, you need to have the housing torqued to its final value. The upside is that it will only reduce the clearance slightly, so your good. The initial torque on a TTY bolt set the preload. In that range the fastener is supposed to deform elastically ( stretches and will return to its original length). The 90° turn is supposed to put the fastener into its inelastic range. The clamping force increases to a level where it permanently deforms.

Since you using old bolts, yours have obviously deformed once. The issue is they lose repeatability and will deform at a different clamping force. As a bolt deforms, its initial strength goes up as it work hardens. Past a certain point, the bolt starts to neck down and looses clamping force. The strength per square inch of material is still increasing, but not as fast as the bolt is losing diameter from deforming.

If your old bolts have not deformed past the steep fall off from necking down, you can still continue to tighten them to increase your clamping force. If you notice that the torque needed to rotate them is dropping off as you turn, they are done and won't get you an increase in clamping force. The increase in clamping force might decrease the clearance as the bearing shells get further compressed in the housing and the housing obtains its actual running dimension (the block is machined with the mains fully torqued).

This is all academic since with old bearings you would only be concerned with too much clearance, and its pretty much impossible to go the other way.

Short story, nice to see they held up so well after so many miles and they may even be better than your first set of numbers would indicate. You could have plastigage them using 65 ft lbs and then a small increase in rotation. 45° degrees might just be enough to simulate the correct preload or just get you a bit closer. Not as good as using a new set of bolts and then throwing them away, but a bit better than just using the TTY preload.

I'm sure there is a procedure in the manual that outlines how to measure without throwing away a set of bolts, but the only way to get an accurate measurement is to use the fastener preload the motor will be run with, fortunately yours is fine. Before taking the old bolts out you could mark them for location and rotation that would get you to very close to the original clamping force. Could be a cheap way to get the correct clamping load with used fasteners.
Well I just used the old bolts because I didnt have new ones.New ones have been ordered.I just wanted to check the clearance for myself to make sure I didnt have any issues.However new ACL Race bearings will be getting installed along with new oem bolts.I know alot of people swear by the billet mains and arp bolts but I have yet to see the oem main bolts fail on a engine build.Unless the engine is making well over 550whp thats a different story all together.