So i hang out on driver and i need some help. Here is the thread i have over there http://g35driver.com/forums/forced-i...ker-build.html
Anyways I have the gtm 4.0 stroker kit and i started putting the bottom end together yesterday. i got the crank in and torqued down and everything was ok. I started putting the pistons in and just hand tightening the rods on the crank. Once i had all the pistons in the crank still turned normally but once i started torquing the rods down after each one the crank got harder and harder to turn. By the fourth rod i couldnt spin it at all. I have checked the rod clearances and they are ok .0018. Checked the rod caps to make sure i put them the correct direction and they were all ok. I have plenty of assembly lube. It seems like the clearance is too tight but i have checked multiple times. I need help anyone have any suggestions? Thanks.

 

lubed the cylinder walls???

 

yep. everything moves free until rods are torqued.

 

Half inch drive with socket on the crank? When I assembled my friends ls6 it was hard as well but turned fine with the ratchet and socket

 

it wont even turn that way

 

You should be able to set a torque wrench to 20 ft lbs and turn the crank. How did you check clearances? I can tell you right now its clearances which is why i ask.

 

Yea i have come to the conclusion that it is clearances but the weird thing is i checked all the rods with a bore gauge and micrometer and got .0018-.0019. The crank is rotating with 11 ft lbs with everything installed and the rods hand tight. When i plastigauged the rods i was getting a clearance of .001-.0014 but i never trust that stuff anyways.

 

This is why I paid to have mine assembled.

Good luck!

 

Not trying to be insulting but sounds like you might not have the bore guage calibrated correctly. Plastiguage is inaccurate hence the wide range you got with it but as you can see its alot tighter then you thought. Prob should pull the bearings apart might have grooves in them from trying to turn it and they are prob junk. You def need bigger clearance bearings though since your going with a stroker im guessing your going for big power, you need AT LEAST .0022 clearance. Put it this way a small block chevy has smaller diameter bearings
so smaller clearance and has 0 issues running clearances as big as .0032 the specs in the fsm are just a starting point rough estimate when going for big power. Its takes experience to determine proper clearance.

 

I set the gauge correctly. I zeroed the gauge on the rod journal and then miced the crank and placed the bore gauge in the mic to see what the clearance was. I did this multiple times and came up with the same values every time. I even took everything apart and checked it again after the crank was not turning thinking i got the wrong clearances the first time but i got all the same values again. I do this stuff all the time at work so i know what im doing and thats why im so confused. I am going to order new bearings tomorrow and see what results i get. Oh and when i took it apart there were no grooves on the bearings. They looked brand new still. Im going to have to get the HX acl bearings because im running all standard right now.

 

Never every heard of what your doing. Your supposed to get a micrometer with iso certified length steel. Zero mic on the steel then zero the bore guage about 1/10th inch bigger then journal with the mic. The guage reads how much smaller the journal is vs the size of the bore guage. Zeroing on the journal isnt effective since when you go to measure it the bore guage can compress and give you a false reading, but when zeroing on micrometer the micrometer is set and not being adjusted so its not compressing anything. Thats the standard of every shop ive ever been to or any engine builder ive met, not to mention the instructions for dial bore guages describe the set up process the same way. Im guessing you are compressing the dial bore guage when measuring it giving you a larger reading. In this case the plastiguage is the better reading your probably around .0014 clearance. The new bearings with. 0024 clearance will work although if your going 700+ whp i personally might have the crank polished some to
get that around .0028-.0032

Side note are you sure its perfectly clean? That small isnt even visible and lint particles are enough to stop it from turning. Plus according to clevite 60% of bearing failures are from dirt during assembly.

 

Im not sure what you mean by the bore gauge can compress. It is suppose to compress when you place it in a bore it would even be compressed when you place it in the mic to zero it. My way im just taking the differences to get a clearance. I have the iso certified pieces and the micrometers were zeroed to them. You dont really need those if im just taking the difference. I only really need them if i want a correct measurement off of the crank.

I cleaned everything really well before i assembled it.

 

I think i see what you are saying. Are you thinking i took the bore gauge and zeroed it to the journal and then placed it in a mic and was adjusting the mic until the bore gauge read zero and then took the reading off of the mic to see what to bore is?

What i was doing was placing the mic on the crank and locking it so that it was set to the crank diameter. I then took the bore gauge placed it in the journal and zeroed. I then placed the bore gauge in the mic that is set to the crank and the number i read off of the bore gauge is my clearance.

 

Ahhh i see what your saying now a but different. Not sure but i think you might be getting some readings off. .0019 should be more then enough to spin freely. Granted smaller then i would personally run but should be fine so unsure unless possibly your crank is slightly bent or possibly slightly bent rod thats causing some binding. Theres binding somewhere and i would def wanna find out what it is instead of just throwing bigger clearance bearings in. Mayby have everything rechecked for straightness.

 

Be careful when you do the rod bolts. I've heard all sorts of crazy things happening there.
Are you sure you put the rod caps on the right way? I've heard if you put them on backwards they become impossible to turn.

 

Yea the rod caps were the first thing i checked when it wouldnt spin. I am afraid the rods are twisted. I took them to a shop to get tested and they said they were ok but not sure if i trust them.

 

Maybe the crank/journals are not true (round)?

 

Hmmmmm dont over think it. it's an EASY fix. You just need to trim the edges of the bearings a little bit.

 

That's the problem. I took it to a shop and the chamfer on the crank is too large so the edges of the bearings need to be cut.

 

Does anyone know if the water pump o-rings are different? The factory manual says they are and that one should have a white mark. I bought a complete engine gasket kit and neither of the o-rings i have white mark.