Engine Builders: Babbitt and boring cylinders question

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First Name: Chad
Last Name: Marcheese
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Engine Builders: Babbitt and boring cylinders question

Post by Chad_Marcheese » Sat Apr 13, 2019 9:44 am

Hoping the experienced builders can help me out here. I am curious if the boring of the cylinders happens before or after the babbitt mains are poured---or doesn't it matter? I wasn't sure if any of the heat involved in the rebabbitting effects the roundness of the bores.

I am asking because I have a trusted machinist that I have used for 20+ years building more modern engines, who has done all my machine work for me (I assemble though), and I have to take it to someone else to pour the babbitt.

Also, do any of you use a torque plate when boring, or maybe even an old head machined out for the boring bar and hone?

Les Schubert
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Re: Engine Builders: Babbitt and boring cylinders question

Post by Les Schubert » Sat Apr 13, 2019 10:42 am

I have done it both ways, but prefer to pour the babbit and then get the machine work done AND THEN line bore. I’m sure others have their own opinions.
I trust that the line boring will be located from the camshaft and NOT by centreing in the main saddles.
All the best

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Mark Gregush
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Re: Engine Builders: Babbitt and boring cylinders question

Post by Mark Gregush » Sat Apr 13, 2019 11:34 am

Tom at the Model a Ford Works in Portland Oregon has been pouring Model A Babbitt mains for years. He pours the blocks at room temperature (we are talking about warm not an icy cold shop). He only heats the bearing area in the block to drive off the moisture before pouring. So it's not like the whole block would be heated to any real high temperature. I have never been present when our shop that does the machine work boars the block, but I do not think any torque plate is used. I do not recall seeing any such item in the K R Wilson catalog. Les makes a good point about line boaring the mains after doing the cylinders, would prevent any contaminants from embedding in the fresh cut babbitt. If the block is really really clean it can be tinned, if not make sure the shop understands peening the warm babbitt. Maybe the shop you are using for the pour has done many, does not hurt to ask so you know. If they don't tin or peen, find another shop.
I know the voices aren't real but damn they have some good ideas! :roll:

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Kohnke Rebabbitting
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Re: Engine Builders: Babbitt and boring cylinders question

Post by Kohnke Rebabbitting » Sat Apr 13, 2019 11:09 pm

We have always done the machine work first, and I mean all of it. You don't install babbitt, and then expect to clean the block after, of cast iron grit is tough to remove, with out chemical.

For those that don't under stand centering a Model T crank, as well as others, I will explain it again.

It doesn't do much good to grind a crank on the center line, if you don't set the crank on the center in the block.

What ever the crank is off to the side of center, it can compound the measurement being off at the ball cap.

So the crank has to be centered between the bolt holes, of the front, and rear mains, and a definite for (the Model A) They have to stay in that position, while the up and down position is set, for center distance, that centers the crank correct.

A torque plate does not have to be used, but the final cut in the Align Boring should utilize the main bolts at full torque. DO NOT take any loose until the Aligning Boring is completed, as the Alignment will change.


Erik Barrett
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Re: Engine Builders: Babbitt and boring cylinders question

Post by Erik Barrett » Sun Apr 14, 2019 12:19 am

I am with Herm on this. We like all of the machine work on the cylinders and valves to be done before we do the bearings. All of that involves cleaning and other work that can only contaminate my bearings. When I finish a bearing job I clean all parts and bolt in the crankshaft, then put a bag on the block. Customer builds the engine from that point up.

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Re: Engine Builders: Babbitt and boring cylinders question

Post by Allan » Sun Apr 14, 2019 12:33 am

I have valve work, new valve seats, block decking and cylinder boring all done before the babbit work is done. That way, the pouring and machining of the bearings cannot be damaged during all this heavy work. The final honing of the cylinder bores is done last, to remove any crud left over from the bearing work. It works easily with my machine shop being local.

Allan from down under.

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