Crank issue

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May 10, 2025 | 08:38 PM

#16

tbm3fan

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From: Concord, CA

Turns out the thrust bearing is the issue. I guess I'll need to sand the thrust face to gain some clearance. Thrust bearing is a NOS C7 for the engine but really tight.

May 11, 2025 | 05:35 PM

#17

DaveMcLain

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I've seen that happen before where the flanges of a thrust main get spread out a little bit probably due to rough handling in shipping. Glad you found and fixed the problem.

May 13, 2025 | 08:26 AM

#18

mark a.

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Quote:

Originally Posted by tbm3fan

Turns out the thrust bearing is the issue. I guess I'll need to sand the thrust face to gain some clearance. Thrust bearing is a NOS C7 for the engine but really tight.

You have to seat a thrust bearing. First torque all the other mains, then just snug the thrust bearing cap. Wedge the crank to the front of the block with a couple screw drivers placed in the block against a counterweight, then torque the bolts. Last, remove the screw drivers, take a heavy hammer and something to protect the crank snout. Strike the snout firm but not real hard. This mates the 2 bearing shells and if it still has resistance then look elsewhere for the problem.

May 15, 2025 | 08:07 AM

#19

Destroked 450

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From: Harned, Ky

I’m a little confused with your decisions
The thrust is on main 3 if I’m not mistaken and you said the crank turned fine with mains 1, 2 and 3 in, how is it now the thrust
If you place all 5 bearings in the block and install the crank with no caps does the crank turn easily
On a few warped blocks I’ve had the crank turn tight, try to walk up out of the bearings or actually roll one of the bearings out of position
If the crank turns freely to problem is not in the block
Next install one main cap at a time turning the crank after each cap is installed
I start with the rear main first, then the front, then center with 2 and 4 last, if the crank becomes hard to turn after installing a cap remove that cap and move on to the next until every cab has been installed and checked

If the issue arises without any caps installed you have a warped block
If the issue arises when any of the 5 main caps is installed you have a cap misalignment issue

May 19, 2025 | 01:35 AM

#20

tbm3fan

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From: Concord, CA

Quote:

Originally Posted by Destroked 450

I’m a little confused with your decisions
If you place all 5 bearings in the block and install the crank with no caps does the crank turn easily

With the crank laying on the 5 mains it turns quite easily.

May 19, 2025 | 08:57 AM

#21

Destroked 450

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From: Harned, Ky

May 19, 2025 | 09:00 AM

#22

Destroked 450

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From: Harned, Ky

Sounds like the block may be ok, since you had issues when you installed caps 4 and 5 I’d start with #5 first. Install #5 and snug it down then see how the crank turns, if ok remove 5 and install 4 and check again. Do this with every cap, if there’s a cap alignment issue it’ll show up
Your other option is to send the block and caps back to the machine shop to be align honed, this is probably what’s going to happen anyway

May 27, 2025 | 07:48 PM

#23

tbm3fan

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From: Concord, CA

So I went one by one in the order of 5, 1,4,2,3. Each time it took a bit more to turn the crank and by the time all were in one really had to pull to get it to turn. However, once you got the crank to move it was then very easy to keep it turning through numerous rotations using one hand on a 1/2" ratchet.