Spun bearing question

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TommieDuster76

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Can I turn just the one rod journal that had a spun bearing (its gouged up pretty bad) or should I do all four? All others look good.It's a 383 big block.

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i'll share the sentiment and say do 'em all. the set up is probably the same, so you're not saving on the grind.

yeah, it's more loot to double check/size the rods and the new bearings but if that went down, chances are errybody else is headed to chinatown too.

fix it right, fix it once.
 
Looks like you caught that right at the spin, most wait till the rod knocking or the bearing is shredded and you lose oil pressure. It almost looks like it could be polished out.
 
Believe it or not wayyy back in the day there was a guy you would call, and he'd come out with his equipment and turn the bad journal, mic it and hand you the correct size bearing and you would take it from there. Ha yes, the good old days.
 
Depending on what size it would need to be ground, you might consider getting a "crank kit". I recently got one for a 360. Less money than having the crank done at a machine shop and buying bearings separately. and shorter "turn around" time.
 
You need to be careful about choosing a machine shop to recondition your crank. I believe that mopar cranks have the bearing surfaces induction hardened and that hardness only goes so deep. Find someone with alot of experience and ask if it can be polished out and if not how much he thinks it will clean up at. Again he will only know for sure once he starts grinding, but a experienced grinder will have a good guess. A good grinder will grind that journal first to cleanup first and go from there. I have had cranks that needed to be welded to repair(not a mopar crank).

Back in the day when this engine was popular, most machine shops had an inventory of reconditioned cranks and just swapped them out. Good bye to those days.
 
ch1ll said:
You need to be careful about choosing a machine shop to recondition your crank. I believe that mopar cranks have the bearing surfaces induction hardened and that hardness only goes so deep. Find someone with alot of experience and ask if it can be polished out and if not how much he thinks it will clean up at. Again he will only know for sure once he starts grinding, but a experienced grinder will have a good guess. A good grinder will grind that journal first to cleanup first and go from there. I have had cranks that needed to be welded to repair(not a mopar crank).

Back in the day when this engine was popular, most machine shops had an inventory of reconditioned cranks and just swapped them out. Good bye to those days.
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All very true. That is what concerns me the most. Stay tuned. I'm gonna try and polish it out and mic it next.
 
ch1ll said:
You need to be careful about choosing a machine shop to recondition your crank. I believe that mopar cranks have the bearing surfaces induction hardened and that hardness only goes so deep.

Back in the day when this engine was popular, most machine shops had an inventory of reconditioned cranks and just swapped them out. Good bye to those days.
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They are what is called "tufftried" (sp). It is a chemical pickeling process. It only hardens the crank a few ten thousands of an inch (.000x) deep. Once the crank is "cut" the tufftriding is gone. There were very few shops "back in the day" that could do it. Now I know of none. I have a 170 slant six crank that is standard size, and hard chrome plated so I could run a hard bearing without scoring the crank or pounding out the bearing. The crank was done by Lunati in the mid '70's, and I used a tri metal bearing instead of Babbitt.
 
Charrlie_S said:
They are what is called "tufftried" (sp). It is a chemical pickeling process. It only hardens the crank a few ten thousands of an inch (.000x) deep. Once the crank is "cut" the tufftriding is gone. There were very few shops "back in the day" that could do it. Now I know of none. I have a 170 slant six crank that is standard size, and hard chrome plated so I could run a hard bearing without scoring the crank or pounding out the bearing. The crank was done by Lunati in the mid '70's, and I used a tri metal bearing instead of Babbitt.
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Definitely an interesting quandary. that is why I was exploring cutting only one journal and not disrupting the the factory harness on the other journals. Some say it wont some say it will compromise it.
 
TommieDuster76 said:
Definitely an interesting quandary. that is why I was exploring cutting only one journal and not disrupting the the factory harness on the other journals. Some say it wont some say it will compromise it.
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I wouldn't worry about it. I would either get your crank cut (reconditioned) so all the mains are the same size, and all the rod journals are the same size. That way you will know the bearing surfaces are good. Buy a new set of main and rod bearings in whatever size the shop says to use. Or just buy a "crank kit" that comes with the crank done, complete with bearings. What year is the engine? Is it a forged crank or a cast crank?
PS: Make sure you get at least that one con rod reconditioned.
 
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Charrlie_S said:
I wouldn't worry about it. I would either get your crank cut (reconditioned) so all the mains are the same size, and all the rod journals are the same size. That way you will know the bearing surfaces are good. Buy a new set of main and rod bearings in whatever size the shop says to use. Or just buy a "crank kit" that comes with the crank done, complete with bearings. What year is the engine?
PS: Make sure you get at least that one con rod reconditioned.
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Its a 1969 383. Good advice again! Thanks, very helpful.....
 
About 30 years ago (Wow! It's been that long...) I worked for a place that sold parts in the front door, and had a full machine shop in the back. On my breaks I used to watch the guys turn cranks, bore cylinders, cut valve seats, re-babbit bearings(!), etc, and for the life of me I don't see how one could have only one journal turned. Nor could I see the utility in that, as the crank would already be on the machine....

In my opinion, grind 'em all, or, as has already been mentioned, find a crank kit.
 
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