kossuth

iTrader: (12)

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.

LOnSLO

iTrader: (15)

H series bearings? If so, you're dead on.

Steve Bryant

iTrader: (1)

What is the difference between the Clevite 77 series with and whthout the H? I thought that they would both be the same accuracy regarding thickness.

Steve

kossuth

iTrader: (12)

P series using stock crank

Ferocity02

iTrader: (60)

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.

kossuth

iTrader: (12)

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

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

LOnSLO

iTrader: (15)

Honestly, it sounds like you got H series 1, 2, 4, and 5, and a P series thrust. I know that's unlikely though. If I were you, I would mic the crank.

kossuth

iTrader: (12)

You know that is almost what it seems like. I don't have a Micrometer, just a dial caliper so I can't say 100% that the readings I got were spot on but I got main clearances on the low side of the factory tolerance with the caliper. On a polished crank this doesn't sound unreasonable at all. Factor that in with what you just described to me about the bearings and that would put me out of tolerance like I am. My neighbor doesn't have a dial bore guage like I had hoped so I'm kinda screwed there. I'll probiably go to Sears tomorrow and pickup a good Micrometer and see what else they have. I also wonder if the bearing part numbers are etched into the shells and how to track them, and why that number 3 is weird like that? The end play is spot on also. Like LOnSLO said it's almost like I have a mismatched set of bearings. I need to get a better set of tools to investigate before I go any further. This just goes to show, you must ALWAYS check clearances even when the machine shop that polished the crank are the ones that did the ordering because you just never know. A set of +.001 bearing shells for the will fix this more than likely.

Redline-Motorsports

iTrader: (3)

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.

racer7088

You can also get the FM152Ms in 1s, STDs and Xs to add or subtract oil clearance.

Redline-Motorsports

iTrader: (3)

Exactly!