I just got my crank and pistons in and motor wont turn. I am manualy turning it with 150ft/lb torque wrench and all the torque wrench will do is click. Im afraid if I keep turning it ill brake my cranck bolt or something. Any ideas?

 

someone please help

 

The first thing that I would do would be to loosen all of the main caps and then see if it will turn. If it does, you probably have one or more main bearings with insufficient clearnance. However, it could be rod bearings too or a combination of both.

What have you done do verify your clearances?
Did you use Plastigage?
Have you rebuilt an engine before?
If you just put the upper bearing halves in the block and oil them and lay the crank in with no caps, will the crank turn freely?
Do you know if the crank is straight?
There are a lot of things to check.

Best of luck with this,

Steve

 

It turned when it just had one or 2 pistons in, but not after that. I loosened main caps also. I think it may have something to do with the hellfire rings.

 

my guess would be that you mix the rod caps
From what you post I can see that it was turning ok with 2 pistons
Every rod cap have to go to it's original rod since it was originally crack split from that rod and no cap like the other

 

Im positive there on the same caps. BTW the rods are only finger tight. WOuld that make a difference?

 

I'd still like to get the answers to these questions to have a sense of your experience and what you have checked. Also, what kind of book are using as a guide to reassemble this engine?

Steve

 

my machine guy done it
yes i have rebuilt
the crank is new

 

I would start off by removing the pistons. Then remove the main caps, and look at the bearing and crank journal surfaces to see if you see any evidence of binding or interference. Then, re-clean the crank and bearings and the mating surfaces on the block and main journals. Take some naphtha and lightly coat the main bearings and the crank. Lay the crank gently in the bearings and insert a piece of plastigage in each main bearing. Then without turning the crank, install and torque the caps to spec. Carefully remove the caps and measure the bearing clearance and record it for each main bearing journal. If that is OK, scrape the plastigage off with something like the edge of a credit card. Clean and oil (or use assembly lube) the bearings and journals and lay the crank in the bearings and make sure that the crank will turn freely by hand. Note: new cranks can be bent. They shouldn't be, but they can be bent. If that is OK, snug up the mains and then loosen the center main and check the thrust clearance. Then starting with the center main, tighten each main bearing cap and make sure that the crank continues to spin freely by hand. Did you check your ring clearance on each cylinder? If they are OK, install the piston and ring pack and make sure that you have the correct cracked cap on each rod. Check and record the clearance on each rod with plastigage as described for the main bearings. Note, none of the pistons should stick in the cylinders when they are inserted. Do you know what your piston to cylinder clearance is? Are you installing pistons with offset pins? If so, make sure the offset is in the correct direction. Lubricate each rod journal and bearing and torque to spec. Verify with each added piston that the crank can be turned fairly easily. The torque required will increase slightly with each piston added, but with a standard half inch ratchet turning the crank, it should not be terribly hard.

This is may be more than you want to know, but I just trying to give you some help from a long distance.

All my best,

Steve

 

my 408 shortblock takes 35# to turn with no cam/oil pump...just crank rods pistons and rings

 

The crank is fine and how its suppossed to be. The rings are hellfire and are file fit. I filled them to 22 and after just the first piston it was hard to turn. It is easy when the piston is on top or bottom, but when they get half way up it gets hard to turn. Someone please help

 

your main caps are most likely on backwards. when i put my LS1 together i got the caps on backwards and it would not turn for the life of me, i swore i screwed something up bigtime.. i just turned the caps around and it spun over 100% fine, and has been running fine for the past couple of months.

 

Do you have a pic of them installed so I can double check?

 

no i dont, im sorry..