S10xGN

iTrader: (11)

Should I be worried? Had this block line-bored and here are the results:

#1 = 0.0013"
#2 = 0.0015"
#3 = 0.0016" (0.007" thrust)
#4 = 0.0023"
#5 = 0.0022"

All with standard bearings and a (new) stock LS7 crank, journals measured with a micrometer and bearing bores with dial bore gauge. At least I should have outstanding oil pressure...

Gray86hatch

iTrader: (83)

I would find out where the differences are and fix them.

Tim

A.R. Shale Targa

iTrader: (2)

I'm assuming this is an aluminum block and that the crank has been balanced/polished already.
The two back mains seem good, I'd remove the front three sets of bearing shells and hand scotch brite scrub them in a solvent tank. The last little procedure you can do is put the shell on a workbench, backside down and roll a wrist pin back and forth across the babbit layer, gently rocking the shell back and forth like you're rolling pizza dough. These two goofy steps will get the front clearances in that .0022"-.0023" range.

machinistone

I would want to know what the main housing bore actually measures at...a full .001" spread and with where it's happening it looks like a lazy machinist didn't flip his mandrel if it was a line hone, or a worn line bore machine if it was only bored.

KiwiKid

Agreed, do it once do it it right.

Know It All

Yeah, that's a big difference from front to back. What do the main bores and main journals measure? What brand of bearings?

S10xGN

iTrader: (11)

This is what I have:

---------journal ----- bearing ---- clearance

#1 ----- 2.5598 ----- 2.5611 ----- 0.0013
#2 ----- 2.5595 ----- 2.5610 ----- 0.0015
#3 ----- 2.5595 ----- 2.5611 ----- 0.0016 ----- (0.007 thrust)
#4 ----- 2.5595 ----- 2.5618 ----- 0.0023
#5 ----- 2.5593 ----- 2.5615 ----- 0.0022

The journals are all on the high side of the 2.5595 spec with a variance of 0.0005", the bearings have a variance of 0.0008". These are prolly within my margin of error. All I have read on alum blocks say 0.001 to 0.002 since the thermal expansion will open them up. One of my buds suggested the boring bar was wobbling, IDK, that's out of my control. Personally, I don't see a problem running it as-is. I don't think it's gonna come apart, cost HP, use excess oil, etc. If ya'll can say definitively why I should NOT run it, please post that reply.

Thanks!

EDIT: 171-MS-2199P - Clevite P-Series Main Bearing Set for STOCK CRANK APPLICATIONS

KCS

iTrader: (20)

There's problably some variance in the main bearings. I would try switching out the #1 and 2 bearings with the #4 and 5 bearings. That will sometimes make the difference.

Only .0013" on the mains is too tight for my liking but I have no empirical data to support my opinion. Clevite suggests at least .001" for every 1" of journal diameter, but I feel that's too loose for an aluminum block. That tight clearance might actually be perfectly fine for what you're doing and run forever, but I would want it a little looser. As the saying goes, "Too loose and only you know. Too tight and everyone will know."

KiwiKid

Hi S10,

In principal you should have them all 'nuts on'.002" However, I have seen main's as close as .0005" and live! So you definitely won't have an issue running what you have ended up with.

Cheers,

Mark.

jl sargent

"Too loose and only you know. Too tight and everyone will know." I like that.

S10xGN

iTrader: (11)

Thanks for the input, but I need to put this up until fall. Unbagged it today and there were rust stains (from sweat drippings) in the bores. Hard to work comfortably when it's 104° with an index of 115°...

S10xGN

iTrader: (11)

Had a nice day here today, weather was mid-80's and 35% humidity, so back to work. I pulled the crank, cleaned and inspected everything, and reset my dial bore gauge for each individual main. Also swapped the shells from #1 to #5 and #2 to #4 and got these numbers:

#1 = 0.0017"
#2 = 0.0020"
#3 = 0.0019" (0.007" thrust)
#4 = 0.0021"
#5 = 0.0019"

The first time, I did over-torque the studs to 70# (trying to work from memory) but reset them all when I found out a couple hrs later. I miked each shell in 6 places to make sure nothing was crushed and all spots were within 0.0002". Also checked the studs against ARP's stated lengths and while some were + 0.003", a couple were actually shorter. I feel better now...