i have a slightly used ls1 crank going in a block i have here. i bought standard main bearings from thunder racing (part # 152m). the main bearing journals measure

1st = 2.558
2nd = 2.559
3rd = 2.559
4th = 2.559
5th = 2.558

when i install the bearings i used engine assembly lube. placed the crank in the block everything was fine. when i put the 2 and 3rd main cap on the crank did not spin. if i used a pretty new crank that is still in factory specs why would the main bearings (152m) not work

 

Did you check to see if the crank was bent? That could cause it to stick even if the journals all measured within spec.

John

 

Did you use Plastigauge to check the tolorance before install?

 

am i supposed to be able to turn the crank by hand when it is tightened down.

 

yes...

 

The suggestion about the crank being bent is a good one. Take it to a local machine shop they will be able to tell very quickly.

Do you have the main caps installed in the correct direction? This would definitely cause the crank to "bind" up.

And yes, you should be able to turn the crank over by hand and it should not get tight in any spot during its rotation. If it does, pull it back apart and check. Take one cap off at a time and rotate the crank. If it starts to rotate freely after removing a specific cap, then you need to look at that cap, journal, bearing, etc. closely.

 

Also, look on your bearings to be sure that they were not mispacked from Federal Mogul. On the back side of the bearing shell, you should see "STD".

 

i have installed two cranks already. both did the same thing. does anyone have a pic of the bottem end. i know i have the mains in correct order but better safe than sorry right. standard bearings should not make the crank bind up right.

 

Yes, they are numbered, so it's hard to get them out of order. However, you must have the caps oriented correctly. The caps have little "ears" on them. On caps 1-4, they should face the rear of the motor. Cap 5 is the only one whose "ears" face forward. I'll see if I can find some pics of the motors I have built.

Jason

 

Here is a pic I found on ls1.com. I couldn't find any on my computer:

Main Caps

 

problem fixed. thanks for all the input guys i really am thankful

 

What ended up being the problem? Glad you got it fixed!

Jason

 

i had the "ears" facing the front of the engine. damn i feel dumb. i guess when i washed them i kept them in order but switched them around. spins like a beauty. P.S. if anyone has not biult an engine in there room at 12 midnight. DO IT!!!! its fun.

 

Glad it was something simple. That's why I always put an arrow on the main caps pointing the front before tearing down just for this reason. Here is a pic: (you can see the arrow on the center of the cap).

http://members.***.net/kcr19/maincaps.jpg

 

very good idea. i might have to do that to. thanks again

 

hey jason, i read on another post about ur gap in the piston rings. i have a set of +.005 wiseco pistons. what should i gap them on a h/c motor.

 

If the car is strictly n/a, anywhere from .016-.018 top ring; .020-.022 second. I ran my last 346ci solid roller motor at .016/.020. The motor in my car now (stock pistons/rods; plan on 150-200 nitrous jets) is at .022/.026.

Jason