Crankshaft resistance
Thread Starter
Staging Lane
Joined: Jan 2018
Posts: 67
Likes: 8
From: Pensacola
Crankshaft resistance Got around to start final assembly of the bottom end yesterday. The block is ls1 aluminum and main bearings used are King MB5013XP 001. I measured clearance probably 10 times and consistently get from 0.0014 - 0.0016 on all caps. While using Permatex ultra slick assembly lube the crank shaft while still turn-able by hand gives considerable resistance and comes to a stop immediately after spinning. Thinking something was wrong I inspected every cap for malalignment or damage and everything checked out. So I cleaned and reassembled everything just using oil. After that I get about 3/4 of a turn of continued rotation after spinning it by hand. I ended up installing the crank again with Permatex since it will sit for a few months while other work on the car is done. Everything online I have found seems to say that crank should still spin by hand but will be a little tighter with assembly lube. Does anyone here have experience with thicker assembly lubes and these aluminum blocks with tighter clearances? Just want to make sure this is typical and something I am not thinking of is off. Thanks
Matthew
Matthew
Joined: May 2004
Posts: 1,593
Likes: 267
From: Halfway back on the Highway to Hell...again!
Was any work done to the block? Was it align honed?
You can expect some resistance. If you see videos that someone spins a cranks and it keeps going...They have either high clearances or the mains are near perfect from align hone.
If the cranks turns by hand with little effort, whether it stops when you stop or not, it's fine. What you don't want is heavy resistance where it takes a wrench to rotate with good amount of effort.
I do all my own machine work (align hone, boring, etc) and everything is always perfect. But on my street engines I keep tight clearances. So things are nice and snug. Never had one fail yet.
You should be able to just grab the crank snout and rotate it with normal clearances. But a thick lube like Ultra slick is sticky stuff. I love it and it will definitely make it not spin freely.
You can expect some resistance. If you see videos that someone spins a cranks and it keeps going...They have either high clearances or the mains are near perfect from align hone.
If the cranks turns by hand with little effort, whether it stops when you stop or not, it's fine. What you don't want is heavy resistance where it takes a wrench to rotate with good amount of effort.
I do all my own machine work (align hone, boring, etc) and everything is always perfect. But on my street engines I keep tight clearances. So things are nice and snug. Never had one fail yet.
You should be able to just grab the crank snout and rotate it with normal clearances. But a thick lube like Ultra slick is sticky stuff. I love it and it will definitely make it not spin freely.
Thread Starter
Staging Lane
Joined: Jan 2018
Posts: 67
Likes: 8
From: Pensacola
Only work done to the block was square deck and torque plate hone, nothing done to the crankshaft bore. The machine shop said the crank bore was good to go. I also measured the crankshaft. The main journals average 2.5590 throughout. I have a set of clevite ms-2199P standard size that they ordered and recommended (since I was putting this motor together myself). I measured clearance multiple times using these, even bought a new set of bolts because I checked so many times. Clearance would average 0.0025-0.0030 using the standard clevites. What was confusing is I measured also with plastigage and it consistently came in at 0.0015 except at main #1 it was 0.0020-0.0030. With crank installed (with clevites) using only oil I can notice it does spin a bit easier but never tried with the Permatex. I know plastigage isn't as accurate as a dial bore gage but did not expect that kind of discrepancy. My results are repeatable with a dial bore gage though so I am confident (or maybe consistently wrong). With the King undersize 001 I get consistent 0.0015. This kind of makes me want to clean and put back in the stock bearings to see what clearance the motor was running stock but honestly I am getting tired of quadruple checking this thing. Do you or anyone else commonly have to go with undersize bearing for these aluminum blocks? Do y'all think this warrents further looking into or should I just send it? Again, I CAN turn the crank by hand it just takes about the pressure/grip of a decently firm hand shake to make it go.
The assembly lubes really add resistance in my experience. With oil, I will usually be able to spin the crank by hand and get another revolution or two, but with assembly lube, it almost comes to a stop immediately. I don’t even like to use them because of that. I feel it could hide something binding or hitting.
I think the resistance you're seeing is fine. As mentioned above, Permatex is sticky so there will be a good bit more resistance than usual. The real concern here is the inconsistent main clearances. Can you post photos of the plasti-gauge on a 0.0015 bearing and also the 0.0020-0.0030 bearing? All my mains were 0.0015 when I built my motor and I would have the same concerns as you if one was 0.0020-0.0030.
Thread Starter
Staging Lane
Joined: Jan 2018
Posts: 67
Likes: 8
From: Pensacola
Appreciate the insight guys. In response to 98cherrySS no unfortunately I did not take pictures of the plastigage. My dial bore gage is only the $160 unit from Summit. But it does say its good to 0.0001. I zero it out using a micrometer set at 2.5590 and measure the difference. I have gotten repeatable measurements within a couple ten thousands of an inch about 5-6 times using either the king or clevite bearings. This being said, I thought those values would be more trustworthy than plastigage. Just hoping the Summit bore gage isn't a whole thousandth off and I'm building a super tight motor. That's why I was wondering how often y'all end up needing undersize bearings in an aluminum block whose crank bore hasn't been machined just to further rule out any error on my part?
Matthew
Matthew
