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Crank wont rotate

This topic contains 4 replies, has 2 voices, and was last updated by Nightflyr * Richard Kirshy 4 months, 2 weeks ago.

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    Topic
  • #954982
    david macquade
    david macquade
    Participant

    I am rebuilding a 350 SBC. The engine was taken care of well and rotated just fine, however when i’m trying to reassemble the lower end and I have one rod cap that once torqued prevents the crank from spinning. Now I should say, i kept the same rods with the same cap, there is no chance of mix up, this is original rods and crank also. I have also plastigage it and is in spec, ive even switched the cap to another rod and it locks up the crank, i torqued all the other caps to 40ft lbs and then 45, however anything over 22ft lbs on this particular cap will not allow the crank to spin no matter what rod in any journal. Is it somehow warped? What is the deal and any ideas on how to fix this!!! I need to fix it so i can finish up rotating assembly.

Viewing 4 replies - 1 through 4 (of 4 total)
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  • #954988
    Nightflyr *
    Richard Kirshy
    Participant

    First …. dumb questions:
    Is it facing the correct direction?
    Is the bearing the correct size??
    Is the bearing installed correctly and fully seated?
    Could the cap be warped or twisted? anything is possible, though you would need a surface plate, height gauge, dial indicator and a good angle knee to measure it out to verify.
    Being you’ve localized it to that specfic cap and bearing from there you should be able to narrow it down.

    #955031
    david macquade
    david macquade
    Participant

    Yes it is facing correct way, and yes bearing is correct as i have changed them all around and used plastigage to verify it is within spec. and yes bearing is installed correctly. I have literally taken this thing off time after time, checked, rechecked, moved, adjusted. I’m going crazy. Its possible it could be warped however I’m not sure how it would have happened, its only been 2 weeks since i tore down the engine, i placed each cap, nuts and used bearing in a ziplock bag and labled them all one at a time. I’m lost. It is 100% that cap and only that cap, not even the bearing as I switched them up thinking it would work.

    #955032
    Nightflyr *
    Richard Kirshy
    Participant

    It’s possible that during the life of the engine something may have happened to cause it to warp or it came from the factory that way and worn in.

    #955048
    Nightflyr *
    Richard Kirshy
    Participant

    Just to let you know..
    If the cap is warped..
    ( your not going to like this )
    Chances are you’ll need a replacement, or it may be abled to be honed.
    In either case it means you’ll need to send the bare block, all the caps and hardware to a shop to have them honed to match.
    Now depending on how far they need to hone the block and caps, you may need a new set of bearings to compensate for the machining.
    Side note:
    Depending on the condition of the journals on the crank, you might want to consider getting it reground.
    In which case will aslo affect the size of the replacement bearings.

Viewing 4 replies - 1 through 4 (of 4 total)

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