I just finished installing a Lunati 4.125" crank into my 6.0 iron block. I've torqued the main caps down to 20 lb/ft. The crank turns smoothly but it takes quite a bit of effort. It takes about 20lb/ft of torque to turn the crank. All the bearings are properlu lubed. My question is, is this OK? I'm using ARP studs, so I haven't torqued the down to 60 yet. Any info is greatly appreciated.

 

Make sure you didn't mix up, or put any of the main caps on backwards(if that's even possible).

 

No, they're on right. So do you think I have a problem?

 

You may have no problem, except for tight clearances. What did you set the clearances at?

 

What is your bearing clearance like? Did you have new main caps installed? Are the main caps bore-aligned? Truthfully if there was a real problem, you wouldn't be able to turn the crank at all. I have done a few other non-LS1 engine and learned some things.

 

I bought wahat is supposed to be a compltete matched rotating assembly with bearings. After work I'm going to check the clearances with plasti-gauge. I know this isn't the most accurate method but, it's all I have to work with. The block is brand new from GM. Like I said earlier, the crank turns smoothly, it's just that it takes quite a bit of effort. Thanks again for all the help.

 

If you need a second opinion, call up Bill at Opel Engineering in Streamwood I had him go through my heads and I know he has worked on some LS1 strokers.

 

Silent1:
Question: I'm considering a 4.125 stroker crank too. Did you need to "clearence" the block for this; what rods and pistons are u using?

 

I wish I could give you a straight answer but I can't. The machine shop that did the bore and hone only charged me $80 for everything. I told them that the block may need to be clearanced, they said they'd check. The work was done through my friends sponsor at Windy City Engineering, which is why I didn't get charged much at all. The rods and pistons are lunati 6.125" and 2.100". I used a brand new block so I can't tell where any machining may have been done.

 

FYI, the #1-4 maincaps are marked on the drivers side of the cap. The #5 maincap is flipped around, and the number is on the passenger side of the block. This is with the block upright as it would sit in the car.

Not many people know of this, but you can also align the two halves of the thrust bearing on the #3 maincap. Loosen the #3 main cap bolts, just leave them snug enough so the cap doesn't wiggle. Now, tap the crankshaft forward with a soft face hammer, then tap it to the rear, tap it forward once more and then torque the bolts.

What kind of assembly lube are you using?