Need Help, Pistons binding.

MattK67

New Member
Jun 30, 2004
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I went back and locktited and torqued all of the nuts on my connecting rods last night and now I can't get the crank to turn. I had one of the rod bearings slip, so I straightened it back out and it seemed to fix the problem. I finished torqueing everything down and now the crank is stuck again. I went back through and took all of the rods off and checked the bearings one by one, retorqued them, and it's still seized up. Anyone have any idea what could be binding up?
 
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Does the crank spin by hand in the block with all the main caps torqued down?

Nedd more info.
New rebuild?
block recently bored?
new pistons / rings?
Piston to cyl. wall clearance?
rod bearing clearance?
are you torqueing evenly in steps?
 
Did you use plasti-gauge on the rod bearings? If the clearances are too tight it will keep you from being able to rotate the assembly. Also, use plenty of lube on the bearing surfaces. I used Lucas oil on the pistons.
 
No No

You should not use locktite on rod bolt or bearings. Any bearings damaged should be replaced not straigntened out. I would remove all the rods and clean them and the bearings. Use engine oil on the threads or your torque readings will be thrown off and you will never know the real torque value.
 
If the crank turns freely with the mains tightened down, the bearings are mounted correctly and are the correct size for the crank journals, then you probably have the rods on the crank backwards.
Rods only fit on a crank journal one way due to the offset and chamfer of the bearing. Sometimes a shop will install the pistons on the rods wrong. You install the pistons correctly but the rods are 180' off. Then when you tighten the rod bolts, the bearing jams into the fillet of the crank journal and binds.
 
Are the rod caps being installed in the proper direction?

Are the rod bearings from the same set? Check the rear of them--do they all have the same "size" stamped on them?

Was the crank reground and are the bearings correct for the regrind?

If all is OK then get some plastic guage and check the rod bearing clearance of each journal/rod. Do them one at a time . If in spec, move on to the next hole/rod.