MTFCA Forum

What do you make of this rear main bearing? It is rough, scratched and looks porous. Plastigage measures the rear at 0.0015 clearance at both the front and back end of the bearing. The rear journal on the crank measures: Front: 2.2195 Middle: 2.2195 back: 2.2220 and shows a maximum 0.0003 out of round.

The reason for taking the motor down was a knocking number 2 rod bearing which shed 1/3 of the babbitt shell. I believe that the babbitt poured in the number 2 rod was not centered correctly and the shell was too thin.

I could just have the rod journals touched up and make them all 2.220. Leaving the mains as they are. And buy 4 replacement 3 under connecting rods. This is possible, because the rod journals average large at 2.222. However, this would leave the questionable rear bearing in place. Richard

That's from dirty oil, not changed often enough, and yes it would clean up alright, use wd40 and 320 wet and dry paper then about 1000 to finish. You remove stuff all Babbitt in cleaning it up and it doesn't need to be perfect.

That looks like a reasonably terrible rebabbit job.

Richard

now realizing that this bearing is in the same engine as the "oil line to nowhere", and also knowing the engine is torn down to it's fundamentals...now is the time to send the block to someone who knows what their doing and start fresh. No matter how much a person might enjoy tinkering, an engine like this will provide nothing BUT tinkering and very little driving with piece of mind.

Use that block for a good solid foundation to a new engine.

When I see things like this, I always marvel at the fact that folks had the wherewithal to pour and bore babbit and yet have not the slightest idea of what they were doing or why. Kerry is right, in that the bearing can probably be made to work, and Dan is right that it is a particularly awful job (topped off with what appears to be no thrust on one side, odd oil groove, and channels on the bearing edges designed to spill, not retain, oil).

I was chasing windmills, seeing gaps that are just shadow lines.

On my screen this appears like a Babbitt shmear on the inner surface a shell type bearing. The thrust end appears to me to be loose from the block, making it appear to me as Babbitt slathered on the inside of a shell. If this is the case, was the block over-bored to accommodate the additional thickness of shell plus Babbitt? And if I'm wrong in my interpretation, will those in the know pls elaborate on what's really going on? Best, jb

Never mind.

Thank you all very much. It does not surprise me that there is some shabby work done on this engine. The car had some amateur chroming, that I removed and painted black. The chrome on the bumpers was too difficult to remove so I just bought stainless. I have included a new photo that shows:
The rear main cap, the crank with the 0.001 to 0.003 plastigage smashed and a strange bit of brazing repair to the block. I have also added a new photo and possible explanation to the external oil line discussion. Please continue to help me.

Thank you, Richard

Judging by this bearing, and the trouble you've had with others, this engine need new babbitt, front to rear. BTW, the roughness is not the big issue, it's the fact that the babbitt is coming away from the block and that you've already lost babbitt in other areas. It's just a bad babbitt job from the get-go.

Too bad that Herm is NO LONGER among us. He would have the answer!

Your block likely had a broken crankshaft at one point which may be the source of the block damage/repair.

You're going to want to do a REALLY good job of inspecting that block for soundness before sinking $$ into it and maybe even consider another undamaged block. For the piece of mind it would probably be a good investment, if that damage/repair has any dimension to it.

Are those homemade aluminium/steel shims in the first photo?

You blokes are seeing things that are just not there, it's a normal pour and the shims are still sitting on the block with some dirty oil marks as well, The oil swipes are cut a little rough but that bearing could be brought back to serviceable condition easily.

Kerry wrote: ↑

Sat May 23, 2020 5:49 pm

You blokes are seeing things that are just not there, it's a normal pour and the shims are still sitting on the block with some dirty oil marks as well, The oil swipes are cut a little rough but that bearing could be brought back to serviceable condition easily.

You just may be correct. Maybe the OP could post another photo with the shims removed. The shims are casting a shadow that appears to be gaps between the babbitt and the block. How about it OP?

Does a tool exist from the T era for the oil slot for the T. I have the oil well cutter and the spiral oil groove tools for other than T's. Most of the old blocks I have have a simple slot on either side of the hole in the middle.
Please post a photo if a period tool exist.
Thanks in advance!

The shims are not magnetic and probably not brass.

Posting too many photos:
1. 3 of Rear Main Bearing
2. 2 photos of the knocking #2 rod bearing

Photo of the case repair:

If you have a rod that looks like that, the crank is going to need ground or you will be replacing rods in that one cylinder all the time, since the crank is out getting ground you might as well bite the bullet and have the bottom repoured and bored. Just my thoughts since it is out and tore down.

Better find a block if that is a crack where it looks like broke a crank one time before. Dan