So I'm in the process of rebuilding my LS engine and running into tight of clearances across the board, pretty much showing .0008 (guess). I have standard ACL's which I have used several times with no issues. My crank is standard and I'm using 22 ft lb first then 56 ft lb in the proper order. I have tried three TQ wrenches and all leave me with the same clearances. My main bolts are stock and this is what I am thinking is causing the issue. When these go bad do they show less TQ than what is really applied? For instance my final TQ spec being 56 ft lb but in reality its 60+? I'm probably going to order main studs (ARP) just wanting to know for sure. Thanks!


PS: tried searching for a couple hours for the past three days with no luck finding my answer.

 

No, a measured torque is a measured torque. The only way it could be wrong is if the measuring device itself is incorrectly calibrated. A stretched bolt will not apply a greater torque than measured, it is just simply weaker than a non-stretched bolt. The way to tell if it's stretched is to measure the length & measure the thickness in several different spots along the bolt. A bolt will stretch in the area where the threads are not engaged, either the "un-used" threads or the shank (un-threaded portion) of the bolt.

edit:
Have you actually plastigaged the clearances yet? Factory main journal clearance is 0.0009-0.0017in on #s 1,2,4,5 and 0.0012-0.0019in on #3, so I'd say measure them if you're guessing.
I really doubt it's the bolts causing your problem. Any sludge, varnish, oil, grease, or debris between the back of the bearings and block?

 

Well I can't see all 3 TQ wrenches being incorrect at the exact same TQ (so its not the TQ wrenches). I just used my old crank and plastic gauged it and it comes out the same as the new crank, way tight. My old bearings are ACL's and have the exact same part# as my new ACL's. I even tried going 54 ft lb for the heck of it and came out that same

 

I agree, and was kind of implying, that the torque was correct and not a bad torque wrench since you had tried 3 different ones.
What about getting the exact bearings by following the bearing codes on the block & crank? May simply need thinner bearings. Is there any sludge, varnish, oil (even clean/new oil), grease, or debris between the back of the bearings and block? They should be clean & dry before you put the bearings in.

 

Your bolts are probably just fine, you just need a little more bearing clearance. Factory clearances are good for factory power engines, but if you're planning on making more power, a good general rule is .001" for every 1" of journal diameter. So if your main journals are 2.1644"-2.1654", you should run a bearing clearance of roughly .0022" on the mains. If you're getting .0008" with STD bearings, you won't get enough clearance going with "x" bearings.

I'd say your best bet is to have the crank ground. If you have someone locally that can do it, it usually costs about $60 (for V8 cranks). Tell the grinder you're getting .0008" for clearance and you want .022" and when you get it back, it'll be ground perfectly straight, round, and to the EXACT bearing clearance you want.

If you want to stick with factory recommended clearances, you'll probably be ok with "x" bearings.