nm9stheham
Well-Known Member
Yes, and will grind the upper or lower ends depending on which end needs to be lighter to match the others.
Shims Under Main and Rod bearings
- Thread starter Pompis
- Start date
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nm9stheham
Well-Known Member
OK on the pistons. thanks. You CR will be higher than I computed since I assumed the pistons were the truck style lower compression ones with the round recess in the piston top, as shown in the eBay picture.
Well, we can all understand debt. Is there any copper or any dark color showing through the grey bearing material in the old bearings?
AT-20 would not be a standard marking for .002" undersized, at least that I know of. Make sure that you measure each crank journal at least 2 places at 90 degrees apart around the journal. On the serial number pad on the block, is there a Maltese Cross symbol stamped by the block serial number? And on the number 3 counterweight of the crankshaft, is there an R stamped followed by some numbers?
Well, we can all understand debt. Is there any copper or any dark color showing through the grey bearing material in the old bearings?
AT-20 would not be a standard marking for .002" undersized, at least that I know of. Make sure that you measure each crank journal at least 2 places at 90 degrees apart around the journal. On the serial number pad on the block, is there a Maltese Cross symbol stamped by the block serial number? And on the number 3 counterweight of the crankshaft, is there an R stamped followed by some numbers?
Think the compression will be somewhere 8.8 depending on final measurement.
Here are pictures of the bearing.
When I measured the journals I did check them 90 degrees apart. I did not find any R on the crank and the block got no maltese cross. Below are some pictures on what markings and serial numbers I found on the crank.
Here are a 1 stamped on one counterweight.
Some other nr. In this picture the rod journal looks real bad. This one is the worst looking but it looks better in reality and you cant feel any irregularity even if I use my fingernail.
I guess this is the part nr?
Here are just a picture of the overall condition on the journals. They look better then pictured and you cant feel any grooves and they are very smooth.
Here are pictures of the bearing.
When I measured the journals I did check them 90 degrees apart. I did not find any R on the crank and the block got no maltese cross. Below are some pictures on what markings and serial numbers I found on the crank.
Here are a 1 stamped on one counterweight.
Some other nr. In this picture the rod journal looks real bad. This one is the worst looking but it looks better in reality and you cant feel any irregularity even if I use my fingernail.
I guess this is the part nr?
Here are just a picture of the overall condition on the journals. They look better then pictured and you cant feel any grooves and they are very smooth.
Marcohotrod
Well-Known Member
if the crank is not standard size from the factory, it was stamped on the milled flat on the #8 crank counterweight. you want to measure the bore of the rods where the rod bearings go, with the caps torqued to 45-should be 2.2500"-2.2505"
I understand but it seems to me he is NOT describing that condition.
BigBlockMopar
BigBlockMember
AT-20 is a manufacturer code and the "9 76" is a date code. So, stock bearings.
pishta
I know I'm right....
The crank number is a casting number not a part number. Same casting # can be used on different motors. When they recondition a rod big end, they mic it for roundness. If its out of round, they dont bore it out oversized, they grind a little off the caps parting line and when they put it back together, its factory wide on the ends, and a little short in the caps middle, then they torque it and then hone it out again (material is taken from the Id of the cap) to factory spec. Now its spec round again and the rod didnt change working length, but its a a few thou shorter overall. Undersized bearings are physically thicker but have the same OD as stock.
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