Question for Herm at Kohnke

[700rpm]

Herm, I see you apparently have done some peening on the babbitt before boring. I just heard about this aspect of bearing work at the NW Regional. Would you care to take a moment and explain the theory and result of this process?

Thank you.

[Mike V. Florida]

I know, I know!!!!!

[700rpm]

Tell us, Mike!

[Kohnke Rebabbitting]

Originally Posted by 700rpm

Herm, I see you apparently have done some peening on the babbitt before boring. I just heard about this aspect of bearing work at the NW Regional. Would you care to take a moment and explain the theory and result of this process?

Thank you.

The first thing I should say is, peening Babbitt is not a Theory, as it is one of the most critical steps in keeping the bearing from Breaking up under crank pressure in use.

When babbitt is poured in the cast iron, at any temperature it will shrink away from the cast iron wall. You have to pull the Jig as fast as you can and get it off as not to damage the pour, and manually push the babbitt back to the shell to a tight fit, like a tinned bearing.

So by Peening the babbitt, it pushes the babbitt back to the wall, it also compresses the babbitt to make it stronger. If you do not Peen the babbitt is about anywhere from .000-50, to in extreme cases .003 thousandths, away from the bearing shell, or wall.

So if the babbitt was not peened, now the crank will do the job of pushing the babbitt back to the wall of the block and cast cap. So if you set the crank clearance to .002, and the babbitt has a .001 air space on the block and cap, that now means you will have a .004 thousandths clearance in just a few miles. The down side to that of having the babbitt compress cold is it will break up, and out, not if, but when!!

It is kind of like packing sand under concrete before a pouring, if you don't pack the sand right, the concrete will do it and will move, and when that happens, just like the babbitt, it will break up.

Just about all the bad bearing pictures we see on here, and else where, of new failed bearings either come from Not Peening cast blocks, and rear cast cap, or peening incorrectly.

Also in the steel, Brass bearings, ect., that have to be tinned, just because they were tinned does not in Many cases mean that the babbitt stuck to them, as Temperature is always the up most critical.

The last thing is about the peening tool. The Wilson style covers to much area at a time, and many spots are missed. To use a hammer on it in many cases have yielded a broken Block. This is from trying to peen a bearing with about 5 Big hammer blows, it is spotty at best. Ford did use that style of peening tool, But it was run buy air, or electric with many small blows, while the babbitt was very hot.

I have seen a picture of a Wilson converted to an air tool, which may work, can't say but what I use covers it all.

The first two pictures show the Peened part lines tight no seam, just one metal run into the other.

The second two pictures show the tinned caps as all are steel, even the early rear. Also look to where the Babbitt stops, and the babbitt begins, no seam.

Thanks Mr. 700, Herm.

[Mike V. Florida]

This is actually one step that the taught on their own babbitt pourers either don't know or skip.

[Kevin in NJ]

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When taking apart your used engines you can tell improperly peened babbitt.

Press the edge of the babbitt. If a bit of oil oozes out then the bearing was not properly peened. My brother has seen quite a few blocks with this issue. He has also noticed new babbitt with a slight gap at the edge.

This problem is all too common. I recommend anyone picking up a newly babbitted block to try and put their fingernails between the block and the babbitt and to press on the edge and look for movement. There should be no space or movement.

From the NOS unfinished later cap my brother has you can see the peening Ford used at that time. It appears to be a bunch of stacked "washers" with a bit a space between each washer.

[QGolden]

Wow, thank you for sharing your knowledge. Unselfish folks like y'all sharing information like this gives the rest of us enough knowledge to have an intelligent conversation with a potential engine builder. I have but a couple of truly knowledgeable folks in my life regarding Model A's and one of them just passed away. I really depend on what I get from folks I have met here, both in person and online.

[Gold Digger]

With this kind of information and explanation makes up my mind where I'll get my next Babbitt work done.

[Duffy1]

Thanks ,Herm

[700rpm]

Thanks Herm. There is no question where I will send my next engine, even though you're 2000 miles away. My dad said, "You get what you pay for" and "You can't go wrong with a first class ticket". That's what you offer, and it will be worth the shipping.

[700rpm]

Kevin: Thanks for the tip.