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Old 05-21-2018, 08:43 PM   #1
Born Lucky
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can not turn crank

So I am rebuilding my engine.
I just installed the pistons and torqued them down. Now I can not turn the crank over.
What could have gone wrong?
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Old 05-21-2018, 08:54 PM   #2
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Re: can not turn crank

Lots of things, can you be more specific than I torqued down the pistons.

Were they new pistons? were they numbered? new rod bearings? how much did you torque them. Did the crank turn before you started installing the pistons and rods?
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Old 05-21-2018, 09:06 PM   #3
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Re: can not turn crank

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Originally Posted by kwmech View Post
Lots of things, can you be more specific than I torqued down the pistons.

Were they new pistons? were they numbered? new rod bearings? how much did you torque them. Did the crank turn before you started installing the pistons and rods?
Yes new pistons old rods.
New rod bearing
All were numbered before removal.
I installed crank and it turned freely.
I installed pistons and turned freely.
I started torquing them down.
I started with 30 then tried turning and it would not.
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Old 05-21-2018, 09:09 PM   #4
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Re: can not turn crank

Loosen the rod bolts one piston at a time then try to turn the crank. Then you will likely find which one is binding.
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Old 05-21-2018, 09:12 PM   #5
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Re: can not turn crank

Rod cap on backwards?
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Old 05-21-2018, 09:36 PM   #6
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Re: can not turn crank

engine make, model, and detailed explanation of work done and parts replaced would be optimum for troubleshooting via interwebs..

for what's posted, my swag would be to verify con rods/caps mated and proper size bearings installed correctly..

then torque with plastigage one at a time and verify bearing clearances..

http://www.plastigaugeusa.com/how.html

this is per what is previously stated to imply crank and pistons fitted and installed correctly..

good luck!
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Old 05-21-2018, 09:41 PM   #7
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Re: can not turn crank

Quote:
Originally Posted by Killer Bee View Post
engine make, model, and detailed explanation of work done and parts replaced would be optimum for troubleshooting via interwebs..

for what's posted, my swag would be to verify con rods/caps mated and proper size bearings installed correctly..

then torque with plastigage one at a time and verify bearing clearances..

http://www.plastigaugeusa.com/how.html

this is per what is previously stated to imply crank and pistons fitted and installed correctly..

good luck!
engine 350 SBC 1996
machine shop honed,cleaned block, polished crank.
Pistons and bearing(main and rod) were provided by machine shop.
Plastic gauge was done and were within specs.
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Old 05-21-2018, 10:08 PM   #8
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Re: can not turn crank

My guess would be caps incorrectly matched to rods.
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Old 05-21-2018, 10:29 PM   #9
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Re: can not turn crank

Remember you have new rings on honed out cylinders and new bearings. It won't turn as easily as it did before everything was connected and torqued. It will be tight but you should still be able to turn it. Make sure everything is lubed properly and do the checks mentioned above.
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Old 05-21-2018, 10:37 PM   #10
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Re: can not turn crank

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My guess would be caps incorrectly matched to rods.
I believe you are correct.
In the tear down I number the pistons as I pulled them to match the firing order.
Since I removed the caps first, I numbered them 1-8 straight down.
In the reassembly I installed the pistons correctly but the caps were put in wrong order.
So tomorrow I will remove caps and correct my mistake.
This is my first major engine build and I should have been more mindful !
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Old 05-21-2018, 11:58 PM   #11
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Re: can not turn crank

If the rods were resized, the caps must go back onto the rod that they were on when resized. When you disassembled the engine, the proper thing to do is stamp a number in both the rod and the cap indicating which cylinder it came from. The left side (drivers) is 1-3-5-7. the right side Passenger) is 2-4-6-8.
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Old 05-22-2018, 01:11 AM   #12
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Re: can not turn crank

Even with the new rings and bearings I can still move the crank by hand, not easily mind you but I can still move it some.
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Old 05-22-2018, 06:26 AM   #13
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Re: can not turn crank

If you mixed and matched the rod caps you will have problems. They must stay together and they only go on in one direction.
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Old 05-22-2018, 09:41 AM   #14
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Re: can not turn crank

'96?

Powdered metal rods with cracked caps? It's critical that the caps fit their respective connecting rods correctly. They are mated for life.
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Old 05-22-2018, 10:16 AM   #15
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Re: can not turn crank

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'96?

Powdered metal rods with cracked caps? It's critical that the caps fit their respective connecting rods correctly. They are mated for life.
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Old 05-22-2018, 12:53 PM   #16
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Re: can not turn crank

OK corrected the issue.
The problem started of course by not numbers during break down!
I had all pistons and caps set up on my bench relating to how I pulled them off.
I did not pay attention to the reassembly and mixed sides.
Today, I pulled the pistons and switched sides.
All good.
Thank you for your help everyone.
First build lots of experience, lol
One more question torque spec 45 Lbs is this correct?
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Old 05-22-2018, 01:05 PM   #17
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Re: can not turn crank

I just love a happy ending!

good job figuring it out and good luck with the rest of the assembly!

don't have the torque specs off the top of my head but it should come along shortly...
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Old 05-22-2018, 01:21 PM   #18
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Re: can not turn crank

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I just love a happy ending!

good job figuring it out and good luck with the rest of the assembly!

don't have the torque specs off the top of my head but it should come along shortly...
Yes happy ending are good.
I never anticipated having to take the pistons to the machine shop, so I had my madness all lined up.
When the machine shop requested the piston I lost my tracking.
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Old 05-22-2018, 03:58 PM   #19
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Re: can not turn crank

So the chamferred side of the rods were not as they should be, towards the crank fillets?
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Old 05-22-2018, 09:07 PM   #20
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Re: can not turn crank

^^^I was thinking the same thing. Plus he said he numbered them, but then lost track when they went to the machine shop? How does that happen if he numbered them. I'm thinking this may still be messed up
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Old 05-22-2018, 11:14 PM   #21
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Re: can not turn crank

I'm thinking you may be right. He said he numbered the pistons and the rod caps. But now he has new pistons and had the caps mixed up but now says he has it straightened out. The caps can't just go where you 'think' they belong.

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^^^I was thinking the same thing. Plus he said he numbered them, but then lost track when they went to the machine shop? How does that happen if he numbered them. I'm thinking this may still be messed up
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Old 05-23-2018, 12:41 AM   #22
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Re: can not turn crank

The caps also have to be in the correct orientation to lube the wrist pins.
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Old 05-23-2018, 06:36 AM   #23
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Re: can not turn crank

I pulled the piston with the block upside down .
So as I pulled each piston I put them on my work bench.
Also each cap was bagged and tagged.
After everything was removed I took the block to the machine shop.
The machine shop wanted the piston so I returned home and at that moment I tagged the pistons( they was tagged as if the block was right side up)this is where I messed up. I should have tagged as if the engine was upside down.
Now comes time to assemble and I forgot what I did. So what happened is that I inserted the 1,3,5,7 pistons where the 2,4,6,8 pistons should be and the 2,4,6,8 pistons where the 1,3,5,7 should go.
After, thinking and reading your responses I discovered what went wrong.
So I pulled everything out and corrected the screw up.
Engine turns nice and the cap orientation looks correct.
My biggest error and one I will not forget is to THINK a little more.
This could has cost dollars!
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Old 05-27-2018, 10:52 PM   #24
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Re: can not turn crank

You lined up the notch on the caps for the bearings right?
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Old 05-29-2018, 06:09 PM   #25
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Re: can not turn crank

Quote:
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You lined up the notch on the caps for the bearings right?
notch on same side
all good now
torque down to 40
crank turns nice
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