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Spun Rod Bearing. What do i need to do to rebuild?

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Old Feb 26, 2009 | 03:03 AM
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From: Mountain View, CA
Car: 1991 Chevrolet Camaro Z28
Engine: 350
Transmission: Tremac T-56 6 Speed
Axle/Gears: 10 Bolt 3.73 POSI
Spun Rod Bearing. What do i need to do to rebuild?

I spun a rod bearing on #5. Also my rings were shot. There is no damage or ovaling of the crank or rod. Also Cylinder walls or not scarred/perfect.

What would i need to do to get it running and back together?
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Old Feb 26, 2009 | 05:54 AM
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Car: '82 Z-28
Engine: 355
Transmission: TH-400, 8" ATI MRT
Axle/Gears: Moser 9", 4.56's
Re: Spun Rod Bearing. What do i need to do to rebuild?

You have two options. Either buy a new rod for that cylinder, or take it to a machine shop and have it resized. They will grind the cap down (where it mates to the rod) and resize the hole. If I were you I would have them all checked/resized if necessary (or buy new rods; i'm not sure how much it is going to cost you to have 8 rods resized) and install quality new rod bolts and rings, bearings, etc.
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Old Feb 26, 2009 | 01:33 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Did the rod bearing "spin" in the rod? If so, there is little chance that neither the crank nor rod were damaged.

Or, did the bearing surface just get wiped out? That can happen without the bearing "spinning". But, the crank is usually worn or damaged as well.

The rings are shot? How do you know?

Sounds like the whole thing needs to be taken apart, cleaned, and carefully checked out. Not likely that it won't need machine work.
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Old Feb 27, 2009 | 12:19 PM
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Re: Spun Rod Bearing. What do i need to do to rebuild?

If it were me, I'd pull the crank and have a machine shop check it out. Along with the rods. My local shop charges $30 to check/repolish journals, $70 to regrind. Rods are $2.50 (each) to check, $10 (each) to resize. For doing all 8 it's $100, almost in the range of a set of stock replacemnet rods. For me it would be cheap insurance that everything was correct.

I replaced rod bearings in a motor once that had "spun" a bearing, fired it up and it still knocked (not as bad, but it was still there). Even though the clearances were within spec. Now every motor I do gets the crank check/ground. Money well spent if you ask me.
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Old Feb 27, 2009 | 12:56 PM
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Car: '87 IROC
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Re: Spun Rod Bearing. What do i need to do to rebuild?

If the rings are shot, you probably have a lot of miles on the engine, yes?

If you just want it to run, just deal with the one rod. If you want it to last a while, I'd start looking for a short block and heads or a complete engine.

I grew up in Mountain View, CA.
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Old Feb 27, 2009 | 08:35 PM
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From: Mountain View, CA
Car: 1991 Chevrolet Camaro Z28
Engine: 350
Transmission: Tremac T-56 6 Speed
Axle/Gears: 10 Bolt 3.73 POSI
Re: Spun Rod Bearing. What do i need to do to rebuild?

I know the rings were shot because it had a lot of blowby ie. in TB etc.

The #5 siezed and wore the crank not the rod.

I am probably going to just throw in a brand new crankshaft i have for another motor in it.
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Old Feb 27, 2009 | 09:31 PM
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Car: 87 Firebird, 90 bird coming soon
Engine: 355 Chevy Vortec Heads TPI, LT1 inj
Transmission: 700r4
Axle/Gears: 2.77 posi 9-bolt
Re: Spun Rod Bearing. What do i need to do to rebuild?

You will need to do a lot of work. I'm doing a motor for a friend now that has 6 pistons with broken rings and the crank needs reground because it took out the rod and crank bearings from lack of oil. If you have a spun rod bearing, best thing to do is get all the rods checked and either a new crank, or regrind yours. Don't forget to get the correct bearings when you are putting it back together. Also, don't forget to get the cylinders honed so the rings seat correctly and seal properly. Measure everything you could think of with feeler gauges, dial indicator and plasti-gauge.
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Old Feb 27, 2009 | 09:35 PM
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From: Mountain View, CA
Car: 1991 Chevrolet Camaro Z28
Engine: 350
Transmission: Tremac T-56 6 Speed
Axle/Gears: 10 Bolt 3.73 POSI
Re: Spun Rod Bearing. What do i need to do to rebuild?

Originally Posted by birdtojag
You will need to do a lot of work. I'm doing a motor for a friend now that has 6 pistons with broken rings and the crank needs reground because it took out the rod and crank bearings from lack of oil. If you have a spun rod bearing, best thing to do is get all the rods checked and either a new crank, or regrind yours. Don't forget to get the correct bearings when you are putting it back together. Also, don't forget to get the cylinders honed so the rings seat correctly and seal properly. Measure everything you could think of with feeler gauges, dial indicator and plasti-gauge.
Mine is not a lot of work your friends is. If it broke rings it more than likely scarred the walls so you will need to oversized the bore. while mine spun one rod but it did not damage the ord it damaged the crank. So my putting a new crank in with new bearings etc. I will be fine.
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