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#1
07-05-2006, 01:25 AM
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frozen crankshaft
I just installed a new crank into my sbc 350 and after torqueing down the caps the crank will no longer turn. I torqued the bolts down to specs but should I back them up a bit? I know if I don't mention this someone will ask so yes I am also using new bearings.
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#2
07-05-2006, 02:22 AM
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Re: frozen crankshaft
oooh....man.
The best answer is, take it to a machine shop. To answer the question though, no. Backing off the torque is NOT the correct answer here. You have a problem. It could be something silly, such as putting the caps on in the wrong order. You may have the wrong bearings. You really should get everything mic'd either way. Guessing that the OE bearing sizes will work can be a very expensive guess.
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life begins at 10psi of boost Three turbo'd motorcycles and counting. 
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#3
07-05-2006, 11:08 AM
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Re: frozen crankshaft
I agree ^^^ Wrong bearings, incorrectly machined crank or swapped caps. You have to think of bolts as really strong bungee cords. They have a specific torque rating because they are the strongest at a certain stretch. If your main caps are supposed to be torqued to 80 lb ft, its because the manufacturer has determined that any more and they're past the proper stretch and they're weakened. Any less and they aren't stretched enough and they'll snap or back themselves out. Keep the proper torque on them.
__________________
Dragging people kicking and screaming into the enlightenment.
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#4
07-05-2006, 01:03 PM
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Re: frozen crankshaft
well the bearrings I'm using are the recommended bearrings for this particular crank, or so says sumitt racing anyway I'll fumble with the caps and see what is what.
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#5
07-05-2006, 05:04 PM
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Re: frozen crankshaft
You lubed them up right?
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#7
07-05-2006, 07:31 PM
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Re: frozen crankshaft
Ok, I know it sounds like a stupid question but I have seen people 'dry' assemble a motor before.
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#8
07-13-2006, 10:04 PM
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Re: frozen crankshaft
If the bearing clearance is ok and the thrust clearance is ok , and the main caps are all correctly postioned then it is a slightly bent crank and a slightly out of aligned main bores. Some times a very heavy handed bang on each end of crank will allow it to spin because the bearings may not be aligned well. Use a sledge hammer and a block of wood.
If problem persists then remove each cap one at a time inspecting the bearings for shiney spots especially at the edges where the crank radius is close. and try to spin it at each cap removal, you will find 1 or 2 that are at fault and it is usually the rear one. or a middle. This is especially true if the crank was ground a lot. I am curious as to whether or not the bores were checked for alignment and/or size or resized honed or bored and what the clearance is on the main bearings and / or what the crank measures?
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