[ReelFun]

I was test fitting my 10 under crank on my 389 build today. No rear main seal installed yet. Put the crank in with the bearings and assembly lube applied. Torqued down the caps starting at 20 pds in 20 pd increments to 100 and 120 on the rear cap.

Tried turning the crank and it turns but it seems kind of hard to turn. I put the torque wrench on it and it turns with less than 20 pd pressure. Is this normal? I read in Rocky Rotellas book that it should turn easily by hand.

[mgarblik]

From what you have posted here, you installed it correctly, but you have a problem and need to stop and figure it out. With the crankshaft installed as you have described, you should be able to push on a counterweight and the shaft should turn easily. Or you should be able to turn the crankshaft from the snout with your thumb and index finger. Did you measure your bearing oil clearance with Plastigage or have it checked with a dial bore gauge?

[ReelFun]

Yes. they all mearsured 002 with Plasticgauge. I just tried to check the endplay and there doesn't seem to be any freeplay. Do I need to sand down the sides of the thrust bearing and could that be the cause of the cranksahft being difficult to turn?

[Sirrotica]

You might try loosening the main caps one at a time and see if it frees up. That will at least point you to which main has a clearance problem.

Also examining the bearing halves may show indications of a slight scoring (witness mark) after you rotated it when it was tight.

Check the edges of the bearing halves also for witness marks indicating an improperly ground radius on a main surface transition that is too tight contacting the edge of the undersize bearing.

Thrust surfaces have a spec and if the thrust is too tight it needs to be checked to make sure it's within spec. Sanding the bearing isn't going to give you a perfectly square flat surface and isn't really a good fix for a crank ground out of spec. If it is the thrust bearing sometimes switching to a different bearing, or a bearing from a different manufacturer will give you the clearance needed.

[ReelFun]

Thanks for the replies, I'll try to take a look at it tomorrow.

[steve25]

It sounds like you do have the ideal .005" to .007" crank thrust clearance yet.
As posted , when all is well the crank should spin very easy when done by pushing on a counter weight !

[Tom Vaught]

If the crank, when cut .010, was cut with a larger fillet radius and you are using standard 389/400 bearings the edges of the bearings might be dragging on the crank fillets a bit.

Many engine builders, in the old days, would scrape a small chamfer into the edges of the bearings.

Steve,how do you know the OP has the ideal .005" to .007" crank thrust clearance?
Do not remember seeing that number posted. In post #3 he says he does NOT have any 'end play' which I assume means no thrust clearance. Are you his mind reader?

Tom V.

[ReelFun]

Tom, you are correct, I don't have any thrust clearance.

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[54nomore]

I hate to ask, but is #4 cap on backwards? Also, at only .010" under, it would be difficult for the radius to have been changed significantly unless they also didn't grind all the way to the cheek.

[ReelFun]

No, the cap is on correctly.

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["QUICK-SILVER"]

Originally Posted by ReelFun

Tom, you are correct, I don't have any thrust clearance.

How did you check the clearance; dial indicator, feeler guages, the paper pinch...?

With thick assembly lube on the bearings, thrust will be hard to just see or feel for.

I would spin the crank over several times feeling for tight and loose spots.
Then pull the caps and look for witness marks of any kind on the bearings.

[ReelFun]

Just tried to move it with a screwdriver. I couldn't see or feel any movement. I don't have a dial indicator but I will use some feeler gauges.

[Tom Vaught]

If you take the #4 cap off the engine and can barely move the crank forward or backward, but the crank spins easily by hand then the issue is probably the thrust bearing is too tight to the crank thrust surface.

A bit tough to measure thrust clearance without a dial caliper or a dial indicator, but the crank moves easily by hand otherwise then the bearing clearance to the crank radius grinds is probably ok everywhere but on the thrust bearing.

Post up after you make the above check.

Tom V.

[ReelFun]

Thanks, I probably won't get to this today. I am at my daughter's house now.

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[Tom Vaught]

No worries!

Tom V.

[steve25]

Tom I wanted to post "do not" , so yes I was just posting what he should be looking for and did not proof read before posting which always is a flaw in some of my reply's from time to time.

[GRX]

This is why I like to leave the #4 bearing out when trying the first crank install. If it turns freely before, and not after those are installed. You know where the problem lies. I also like to gently tap the thrust main bearings in place with a plastic hammer to ensure they are fully seated against the saddles before placing the shaft in place.

[hurryinhoosier62]

I have a question: was the main saddle align bored or align honed? If so, the thrust cap could be cut crooked. I've seen it happen with the same result: zero end play.

[ReelFun]

No, no align bore or hone on the block.

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[TedRamAirII]

Should the crank be moved a few times front and rear before the mains are torqued down to seat them? Plus I would think about cleaning up those main bearings, like removing the raised spots on the back where they are stamped, etc. There is a post about that somewhere?