main bearing clearance hmm
Thread Starter
Joined: Aug 2002
Posts: 969
Likes: 1
From: New Market, MD
main bearing clearance hmm Just got my block back from the machine shop and dropped the crank in. Well, I plastigaged the mains and had a surprise. 1, 2, 4, and 5 mains all checked out at between .002-.003 and is probiably right around .0025 or so Stock clearance at the max is supposed to be .0021 max. The number 3 checked in around .0015 or so. I am using clevite bearings and understood that these were supposed to be good bearings. I'm gonna see if one of my fellow gearhead neighbors has a really good dialbore gauge that can do bearings and see if it is the bearings or the crank itself. Crank was polished but that was it, plus the fact that the number 3 was significantly different makes me wonder. Anybody have any experiences with Clevite bearings good bad or indifferent.
Did you plastigauge just one side of the bearing, or both sides at once? Clearance measurements include the spacing on both sides of the bearings. Meaning a .002 clearance will actually have .001 clearance between the bearing and the crank.
Thread Starter
Joined: Aug 2002
Posts: 969
Likes: 1
From: New Market, MD
Just one side how I've always done it. I also checked online to see if I have assembled the 10 tractor engines that we still use on our farm incorrectly and have been just running and holding excellent oil pressure by the grace of god. Here is what clevitte and Federal Mogul had to say about how to plastigage a motor. http://www.engineparts.com/it_crankinstall.asp http://www.federal-mogul.com/cda/con...5_6752,00.html
Staging Lane
Joined: Dec 2001
Posts: 90
Likes: 0
From: San Clemente, CA
Bearing Specifications Hi
My experience is that the only way to get Chevy’s tight crank clearances is to use Chevy bearings. The aftermarket bearing manufactures use a different specification than Chevy. This gives higher clearances with non-Chevy bearings.
Chevy’s main bearing shaft diameters as 2.558 to 2.559
Clevite & FM list main bearing shaft diameters as 2.5588 to 2.5593
When I measured FM mains vs. Chevy’s, the FM mains had ~0.0007” greater clearance. This agrees with the difference in the specifications.
I talked to the FM guys at the Winter Nationals last year and they were nervous about running the clearances as tight as Chevy builds them. Some of this may be due to the aluminum block on LS engines compared to iron SBC folklore. I also didn’t get a sense that they compensated for the thin oils we now run.
If you are going to run the motor real hard, you can stay with the greater clearance and regain the idle oil pressure using the larger volume MOOG pump. I went back to Chevy bearings and a ported stock oil pump.
Good luck & welcome to the world of LS engines,
Steve
My experience is that the only way to get Chevy’s tight crank clearances is to use Chevy bearings. The aftermarket bearing manufactures use a different specification than Chevy. This gives higher clearances with non-Chevy bearings.
Chevy’s main bearing shaft diameters as 2.558 to 2.559
Clevite & FM list main bearing shaft diameters as 2.5588 to 2.5593
When I measured FM mains vs. Chevy’s, the FM mains had ~0.0007” greater clearance. This agrees with the difference in the specifications.
I talked to the FM guys at the Winter Nationals last year and they were nervous about running the clearances as tight as Chevy builds them. Some of this may be due to the aluminum block on LS engines compared to iron SBC folklore. I also didn’t get a sense that they compensated for the thin oils we now run.
If you are going to run the motor real hard, you can stay with the greater clearance and regain the idle oil pressure using the larger volume MOOG pump. I went back to Chevy bearings and a ported stock oil pump.
Good luck & welcome to the world of LS engines,
Steve
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever
Verdad Gallardo Thread Starter
Joined: Aug 2002
Posts: 969
Likes: 1
From: New Market, MD
Originally Posted by SNW Vette
Hi
My experience is that the only way to get Chevy’s tight crank clearances is to use Chevy bearings. The aftermarket bearing manufactures use a different specification than Chevy. This gives higher clearances with non-Chevy bearings.
Chevy’s main bearing shaft diameters as 2.558 to 2.559
Clevite & FM list main bearing shaft diameters as 2.5588 to 2.5593
When I measured FM mains vs. Chevy’s, the FM mains had ~0.0007” greater clearance. This agrees with the difference in the specifications.
I talked to the FM guys at the Winter Nationals last year and they were nervous about running the clearances as tight as Chevy builds them. Some of this may be due to the aluminum block on LS engines compared to iron SBC folklore. I also didn’t get a sense that they compensated for the thin oils we now run.
If you are going to run the motor real hard, you can stay with the greater clearance and regain the idle oil pressure using the larger volume MOOG pump. I went back to Chevy bearings and a ported stock oil pump.
Good luck & welcome to the world of LS engines,
Steve
My experience is that the only way to get Chevy’s tight crank clearances is to use Chevy bearings. The aftermarket bearing manufactures use a different specification than Chevy. This gives higher clearances with non-Chevy bearings.
Chevy’s main bearing shaft diameters as 2.558 to 2.559
Clevite & FM list main bearing shaft diameters as 2.5588 to 2.5593
When I measured FM mains vs. Chevy’s, the FM mains had ~0.0007” greater clearance. This agrees with the difference in the specifications.
I talked to the FM guys at the Winter Nationals last year and they were nervous about running the clearances as tight as Chevy builds them. Some of this may be due to the aluminum block on LS engines compared to iron SBC folklore. I also didn’t get a sense that they compensated for the thin oils we now run.
If you are going to run the motor real hard, you can stay with the greater clearance and regain the idle oil pressure using the larger volume MOOG pump. I went back to Chevy bearings and a ported stock oil pump.
Good luck & welcome to the world of LS engines,
Steve
I use bearings that are coated from Calico Coatings. They stock all the LS1 bearings in both FM and Clevite. The coating actually adds a halfa thou and really help dialing in a specific clearance.
