Specs for LT1 crank bolt?
TECH Apprentice
Joined: Feb 2005
Posts: 384
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Are you referring to one of the bolts, or bolt w/ stud?
Main cap bolt: GM part number 12561388. Size is 7/16"-14 x 3.34" length.
Main cap bolt/stud: GM part number 12561389. Block side is again 7/16"-14 X 3.34". The windage tray side is 3/8"-14 thread (-Stud portion is raised 2" above bolt head, but only the last 1/2" is threaded).
Of course, if the bolt threads are messed up, you'll want to tap/chase the threads in the engine block as well. -Which, you were probably going to do anyway -- if you are rebuilding the bottom end...
Main cap bolt: GM part number 12561388. Size is 7/16"-14 x 3.34" length.
Main cap bolt/stud: GM part number 12561389. Block side is again 7/16"-14 X 3.34". The windage tray side is 3/8"-14 thread (-Stud portion is raised 2" above bolt head, but only the last 1/2" is threaded).
Of course, if the bolt threads are messed up, you'll want to tap/chase the threads in the engine block as well. -Which, you were probably going to do anyway -- if you are rebuilding the bottom end...
Last edited by Alex94TAGT; Aug 4, 2005 at 10:19 PM.
Teching In
Joined: Jul 2005
Posts: 32
Likes: 0
Originally Posted by matt94z
No I meant the hub bolt that goes into the crank. It's 7/16-20 x 2 1/4
Buy a new bolt. It is a single use crank bolt to keep the crank hub on the crankshaft. I reused mine and guess what... blower motor.. came loose and when tightened the head broke off. I will check the torque but if I remember it was a lot... like 90 foot pounds.
gary
