Tighter Main Clearances in LQ4
Thread Starter
Staging Lane
Joined: Apr 2014
Posts: 74
Likes: 1
Tighter Main Clearances in LQ4 My main oil clearances (using stock bolts) were right .003 in. Recently I decided to go with arp studs, which could tighten the clearance between .0005 in to .001 in. Is this ok without machining? If I could pull it off without machining or buying new bearing that would be awesome.
On The Tree
Joined: Dec 2011
Posts: 151
Likes: 6
From: Houston Tx
I will tell you what I do in those cases......now, it might not be the accepted method as many people would rather just throw money at it, or get the crank polished. In a situation like this, I take some 2000 grit wet/dry paper, and submerge, and lightly polish the surfaces. I also have had to put the bearings in the block, torque down without the crank in, and polish the mating surfaces. Bearings that are too tight, are a nightmare, and usually spin bearings. Personally, I would polish wit paper, as opposed to buying .001 under bearings, or polishing the crank. But, I am fairly seasoned.
Good luck.
Good luck.
Most engine builders would have the Mains line honed after application of the new studs. In your case the .003" was a bit loose which may have caused low oil pressure numbers. The tolerance from GM for the Mains is 0.0007"-0.00212". Assuming you are using a dial bore gauge and using it correctly, .0005" would be too tight thus requiring machining and probably new bearings.
Staging Lane
Joined: Jan 2007
Posts: 71
Likes: 2
From: st-jean baptiste, quebec ,canada
I build hi performance engines since 35 years ......
main clearances of .003 is best for high revolution .....
I always manage my main bearings tolerance to obtain this specific .003
main clearances of .003 is best for high revolution .....
I always manage my main bearings tolerance to obtain this specific .003
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
3 thou is perfect for iron block LS mains. That is what my motor has and I have 55psi hot idle pressure.
Also, on the ARP studs, I just measured an LQ4 block mains before and after installing ARP studs. The distortion was limited to 3 tenths on the #5 main only.
Also, on the ARP studs, I just measured an LQ4 block mains before and after installing ARP studs. The distortion was limited to 3 tenths on the #5 main only.
I will tell you what I do in those cases......now, it might not be the accepted method as many people would rather just throw money at it, or get the crank polished. In a situation like this, I take some 2000 grit wet/dry paper, and submerge, and lightly polish the surfaces. I also have had to put the bearings in the block, torque down without the crank in, and polish the mating surfaces. Bearings that are too tight, are a nightmare, and usually spin bearings. Personally, I would polish wit paper, as opposed to buying .001 under bearings, or polishing the crank. But, I am fairly seasoned.
Good luck.
Good luck.
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