Bearing tolerances

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Nov 8, 2012 | 12:11 AM

crazy96863

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Cargo Master

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From: Northern California

Bearing tolerances

Found some end play in a few connecting rods; pulled the caps and most had worn bearings although only a few to the point they had play... Trying to figure out what the tolerance for new bearings should be.

Also, this will sound a little dumb but is there any allowance for wear around the crank? What I am asking about is does the crank need to be perfectly round or is it ok to be a few thousandths out?

Thanks!

Nov 8, 2012 | 06:48 AM

baddad457

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From: south louisiana

I've "re-bearinged" many cranks without turning them. If the journals do not have any visable signs of wear, they're usually good to go with new bearings. Most Ford cranks are incredibly tough. The 351W I put back together in my 95 was done with a used crank of unknown history, sat in a shed for a couple years, I brought it home, cleaned the journals up with emory cloth, bought new .001 undersized bearings and used it like that. With a std volume oil pump, the pressure at idle is 30-40 psi hot.

Nov 8, 2012 | 08:41 AM

crazy96863

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Cargo Master

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From: Northern California

I think the oil pump this thing has is another issue; it might explain some of the excessive wear it has in a few areas. I was going to get a standard pressure, high volume pump from summit for $35 or so just for safe measure.

Thats reassuring about the crank journals... Would you even check the tolerances on new bearings? There are no signs of wear. The top bearing on most rods were all copper/brass looking but there is no scoring or anything.

Nov 8, 2012 | 06:46 PM

baddad457

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From: south louisiana

Quote:

Originally Posted by crazy96863

Thats reassuring about the crank journals... Would you even check the tolerances on new bearings? There are no signs of wear. The top bearing on most rods were all copper/brass looking but there is no scoring or anything.

It's not a bad idea to do so, but I've done several in the past few years without doing so, and so far, nothing bad has become of it. All these motors were roller 302's with over 100K miles on em. All had good oil pressure afterwards and none exibited any unusual noises in operation. It's your call, but like I said, if the journals aren't scratched or scored, they should be OK.

Nov 8, 2012 | 06:50 PM

crazy96863

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Cargo Master

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From: Northern California

Cool cause thats what I wanted to do. This is that replacement motor for the boat; I just want to get it done so it wont rip itself apart but nothing super expensive; basically a reliable j/y build. A buddy was trying to get me to regrind 'just cause' the motors out already but I dont want to put that kind of money into it right now. Thanks for all the feedback.