bearing are cheap ...and you are there anyway
Used 360 main bearings evaluation
- Thread starter 65 Cuda 340
- Start date
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OK, I'm still of two minds, but I just ordered a NOS set of TRW .010 fully grooved mains from ebay for $45. If I decide to replace one or both bearings, I'll have them. If not, they'll keep.
Will still rotate the crank 360 degrees to check for any damage to it.
Will still rotate the crank 360 degrees to check for any damage to it.
Are you running an HV oil pump? You'll lose some oil pressure with full groove main bearings. I recommend an HV pump with full groove bearings.
What do the rest of the bearings look like? You ordered a complete set why not change them all at the same time
Whoa there. One step at a time. I'd love everything to be perfect, but there's also "if it ain't broke, don't fix it." The more I mess with it, the greater the likelihood I'll mess something up. I'll think on it some more before I just jump in. But thank you for your thoughts.
exactly amigo. letting the magic out is easy, putting the magic back in is not and usually winds up costing a bundle!
TT5.9mag
Two atmospheres are better than one
If you don’t measure the clearance you have no idea if the bearings need to be changed or not. If it ran a long time and had good oil pressure, chances of the old bearings having the correct clearance are better than the new bearings having the correct clearance. You’d be surprised by how many bearings come out of a package and are out of spec. If it ain’t broke, don’t fix it.
OK, I have thought and thought about this, and have new bearings now. But this morning, I took one more look at the old bearings and have decided just to re-use them. I think the pictures make them look worse than they are, and the groove disappears less than a quarter of the way around, so whatever caused it disappeared pretty quickly.
I just wasn't super confident in my ability to remove the old bearings while the engine is in the car. Would have tried it anyway though, or maybe just pulled the motor out of the car and taken it apart, if it had not been running well, no vibration, no funny noises and really good oil pressure. Also, I have a 416 rotating assembly ready to go if need be, although that would be a much longer term - and expensive - project that I'm disinclined to get into at this point, given the many other things that are on my to-do list.
I will again note that the short block is the product of a stock type rebuild back in 1991, no machine work to the block except for the .030 overbore, stock rods (albeit rebuilt with good bolts), stock cast crank turned .010/.010, stock type cast pistons. Hasn't even been balanced. Cost me $1500 to totally rebuild the motor. Spent more than that on the top end/exhaust over the years, but the short block is low dollar.
In addition, the original main and rod bearing clearances were kinda tight for a performance motor. I did measure them back in 91 and got this:
Mains: #1 .0015; #2 .0020; #3 .0020; #4 .0015; #5 .0012
Rods: #1 .0015; #2 .0010; #3 .0015;, #4 .0010; #5 .0018; #6 .0015; #7 .0011; #8 .0011
I suspect these clearances are at least part of the reason for the wear these two mains show, given that the motor has seen 6 grand many times over the years.
Anyway, it is what it is. If it lasts, OK. If it doesn't, time to put together another motor.
I just wasn't super confident in my ability to remove the old bearings while the engine is in the car. Would have tried it anyway though, or maybe just pulled the motor out of the car and taken it apart, if it had not been running well, no vibration, no funny noises and really good oil pressure. Also, I have a 416 rotating assembly ready to go if need be, although that would be a much longer term - and expensive - project that I'm disinclined to get into at this point, given the many other things that are on my to-do list.
I will again note that the short block is the product of a stock type rebuild back in 1991, no machine work to the block except for the .030 overbore, stock rods (albeit rebuilt with good bolts), stock cast crank turned .010/.010, stock type cast pistons. Hasn't even been balanced. Cost me $1500 to totally rebuild the motor. Spent more than that on the top end/exhaust over the years, but the short block is low dollar.
In addition, the original main and rod bearing clearances were kinda tight for a performance motor. I did measure them back in 91 and got this:
Mains: #1 .0015; #2 .0020; #3 .0020; #4 .0015; #5 .0012
Rods: #1 .0015; #2 .0010; #3 .0015;, #4 .0010; #5 .0018; #6 .0015; #7 .0011; #8 .0011
I suspect these clearances are at least part of the reason for the wear these two mains show, given that the motor has seen 6 grand many times over the years.
Anyway, it is what it is. If it lasts, OK. If it doesn't, time to put together another motor.
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