wrong rod bearing size?

steven in Tn · Sep 3, 2017

finally got my engine back from machine shop and started putting it back together today checked main bearings with plastigage and all good, got to the rods and when installing them on the rods and caps didnt think they looked right. held the rod and caps together and the bearings stick up to high as leaves a gap about .020 between the rod and cap as seen in the pic below. it has std and the correct part # stamped in the bearing. what are the chances it was stamped wrong? when i put the old bearings back on there is just a slight gap between rod and cap.

Welding man · Sep 3, 2017

Did you have the rods reconditioned? Are all of the rods the same? Did they grind the caps
and forget to finish the honing? There is some crush built into the new bearings but not
.020. You need to check part numbers.

john in la · Sep 3, 2017

I can believe they were stamped wrong.
At least you found it before you put it all together.

I rebuilt a truck motor a few years back.
When I got it running I had little oil pressure and zero oil pressure at idle.
I fought with that thing for 2 days.
Finally figured out that 6 of the 12 new lifers were to small in diameter.
They were either made wrong or boxed wrong.

steven in Tn · Sep 3, 2017

(quoted from post at 11:25:42 09/03/17) Did you have the rods reconditioned? Are all of the rods the same? Did they grind the caps
and forget to finish the honing? There is some crush built into the new bearings but not
.020. You need to check part numbers.

nothing was done to the rods other than putting new pistons on them

M-MAN · Sep 3, 2017

Very good chance. I've had to toss inserts like that myself. Go to napa and order a set of Clevite's and all will be well.

Ultradog MN · Sep 3, 2017

Similar thing happened to me this summer.
Had my Ford 3 cylinder crank ground. Ordered
.020 under bearings from this site.
Installed the main bearing halves in the
block and went to set the crank. The crank
would Not cradle.
Checked and rechecked. Finally got my mics
out and discovered #2 main bearing they sent
was made for .030 under. Tisco box was a
sealed set.
YT was very good. Called me back a couple
times. Tisco called me too.
They sent me a complete new set and all was
well.

David G · Sep 3, 2017

Did you check the rod for round?

steven in Tn · Sep 3, 2017

brutus49DC · Sep 3, 2017

the od of the bearing does not change regardless of the undersize except in newer engines with broken rod/cap assembly's, even if it was stamped wrong it would only change the id. ,big ends should always be checked and re-sized if needed on any engine rebuild, manufacturers error could be possible, you need to measure the bearings and compare them to specs in a bearing book like the one Federal Mogul issued

rustred · Sep 3, 2017

that is correct to have that stick up... as that is your brg. crush. when torqued to spec it holds the brg. in place in the rod. always a good idea to have the rods resized when doing a crank. be surprised how rods get out of round.
put the rod with brgs.in a vise and torque it carefully to spec and see what happens. quite sure you are ok.

fixerupper · Sep 3, 2017

Years ago I overhauled a 196 cube 62 AMC Rambler car engine that had various sized rod journals from the factory. Being young and in a hurry I did not mic all journals or check the bearing shells to find this out. When I got it running the oil pressure dropped after it warmed up. Talked to my machinist friend and he asked me if I measured all of the journals I said uh, no. He claimed AMC pulled tricks like that. When I took it back apart the crank was stamped .010 on three journals. Like the other guys said, out of normal things can happen.

kevinthefixer · Sep 3, 2017

(quoted from post at 12:28:09 09/03/17) Years ago I overhauled a 196 cube 62 AMC Rambler car engine that had various sized rod journals from the factory. Being young and in a hurry I did not mic all journals or check the bearing shells to find this out. When I got it running the oil pressure dropped after it warmed up. Talked to my machinist friend and he asked me if I measured all of the journals I said uh, no. He claimed AMC pulled tricks like that. When I took it back apart the crank was stamped .010 on three journals. Like the other guys said, out of normal things can happen.

Never saw that from the factory, but I'll attest that AMC did some scancy stuff. I have seen "factory rebuild" motors built that way.

gene bender · Sep 3, 2017

Place the old bearings rainbow like and put the new ones beside them to check if they are for your engine. They should be the same hieght Possible for you to have the wrong ones. Not too long ago putting new bearings fromn machine shop after grinding crank every thing went good till the last rod then the crank got too tight to turn found after removing the bearing and reading the # it was a 30thous over and the crank was ground 20 so that bearing got packed in the wrong box from factory. No wonder it was too tight. That bearing was 10thous too thick. Yours seem to be too long. Get the #s checked

Janicholson · Sep 3, 2017

I think you are correct. If the shell and rod are very clean, the shell will stick up a few thousandths. The pic looks like it was all pushed to one side, (which means the rod cap is enlarging the actual crush. If the numbers are corect, put it together with plastigauge in it to assess the real clearance. Jim

504 · Sep 3, 2017

Looks normal to me.

Steve@Advance · Sep 3, 2017

You're probably OK, but if you want to assemble it, watch it closely as you torque it down.

If the gap doesn't close up with the bolts slightly tightened, stop, take them back to the machine shop.

If they are wrong, the bearing will tighten up on the crank, and the rod will then need to be reconditioned, as it will be out of round.

steven in Tn · Sep 4, 2017

went ahead and tried one with plastigage last night and it was with in spec and turned good. i have never put together a engine with that much crush to the bearing. got all 4 in and it turns nice and smooth

Janicholson · Sep 4, 2017

Thanks for the update. Good to Know. Jim

Mike(NEOhio) · Sep 5, 2017

It's possible they're wrong. I got a set of FM mains for Buda and the #4 thrust bearing had no oil hole.

wrong rod bearing size?

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