Grant Winston

Hello all, I'm Doing a basic rebuild on a 94 lt1 2 bolt main block that I got for free. The block has been cleaned up at the machine shop and showed no major wear or damage. The crank had some wear so the machine shop cut/resurfaced it. I'm at square one installing the crank and torquing the mains to spec, checking for main clearance and runout. I'm getting .001-.002 on the plasti gauge with some assembly lube on the bearings. I'm torquing everything down to 77 ft lbs in two stages based on the book I have. My issue is that the crank just doesn't spin as easy as it should. In other videos it looks like it takes little effort to spin it by hand. Mine takes effort and feels like its sticking, like assembly lube stickiness. No metal on metal or any strange sounds. I used a big flat head screw driver to check runout but I must not have gotten enough leverage because the dial gauge didn't move on the crank snout. I really don't want to screw this up. Are these numbers right? Ive seen a lot of conflicting information on torque specs and sequence. I'm reusing the stock bolts. Really appreciate any help advice for a newbie engine builder

gjohnsonws6

iTrader: (12)

How much was the crank turned down? .001 is too tight. Do not use assembly lube when doing plasti gauge. Are you trying to turn it with the plasti gauge? Caps in correct locations?

noice

This is a critical, but that thrust bearing must have adequate runout or it wont turn. Use an absolutely flat surface and some light sandpaper to get the clearance that you need. Feeler gauges work for this.

The rotating assembly shouldn't get harder to turn until the pistons are in and all the rings are causing friction.

kgkern01

iTrader: (10)

I agree, the clearance is too tight, I had the same issue when building my 385, had to go to Clevite X bearings to gain the clearance I needed.

Grant Winston

I don't know how much the crank was cut, I have to check on that. In the meantime, I cleaned off all of the bearing surfaces, applied plastigauge to each bearing, then torqued everything down again. The readings came back at .0015 for the first 2 bearings, and the same .002 that I got before. Confused when you say .001 is tight, that's thickest line on the plastiguage, so wouldn't that indicate a loose measurement? The assembly lube didn't appear to change anything. HP Books 'How to rebuild small block chevy LT-1/LT-4 Engines' indicates a first main bearing clearance from .0007 to .0021. By that measure I am ok. trying to resist the urge to just go ahead with the build. Let me know what you guys think. Thanks for the feedback.

Grant Winston

wait, thicker line mean its a tighter tolerance - scratch that question. long day!

noice

Also what bearings are you using? I had an issue with clevite race bearings where the tang was located wrong and the fillet on the crank rubbed a little on the side of the bearing.

moehorsepower

iTrader: (3)

first off, torque the mains one at a time and check to see if the crank spins freely, when you hit the one that causes the bind, start checking into that cap.

BALLSS

you need the correct oversize bearing for the "cut/resurfaced" crank. The machine shop should provide this measurement & bearing size needed.

if the crank does not spin freely with main caps on.....stop now and find out why

might want to mic the crank journals and confirm size and bearings you have.

Grant Winston

Thanks guys, that helps a lot. I'll try to isolate the problem and call my machine shop tomorrow.

wht97ws6ta

Sounds like you are tight on the thrust bearing if you don't have any end play. Anytime you install a crank you need to snug the thrust cap down not tight just snug and get you something softer like a brass drift a go between the rod journal and counter weight and give it a good couple of whacks with a decent sized hammer then the same from behind where the flywheel bolts up. This locates the rear cap where it needs to be. If that doesn't give you enough end play you will have to sand the thrust surface of the rear bearings down. I don't like to see any less than .005 end play

cardo0

I believe u can purchase Clevite main brgs with an additional 0.001" (-x) or 0.002" (-xx) clearance. Just have to sort out what u need with the plas-gauge. Cheaper than an alignhone or alignbore.

cardo

Grant Winston

Ok, so I removed the crank and thoroughly cleaned everything up. I then applied assembly lube to all of the bearing surfaces, including the sides of the thrust bearing. I am pretty sure this is where I went wrong the last time around. I then installed the #2 and #4 main cap, torqueing them down to 10, 40, and 55 ft-lbs. Everything spun freely, so I moved on to the center, and then the #1 cap, checking for rotation each time. With everything still moving freely, I snugged the rear thrust bearing down and seated it by knocking the counterweight/crank snout with a hammer back and forth. With all bearings torqued to 55, I went back over them one final time to the book specified 77 ft-lbs. It spins nice and easy, and best of all the crank end play came back at .003-.005. The book calls for .002"-.008", so I'm good to go! I think applying the assembly lube to the right spots and using more of it, proper sequence, and seating the thrust bearing were the keys to getting the right finally. I am glad I took the time to get some advice. Thanks for your help! on to filing piston rings and banging them home. if you guys want to check out some more pics and see where my head is at regarding the project as a whole, check out http://gearheadgrant.blogspot.com/