How to pour your own babbitt

You can do it!

| August 2006

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    Fixture for centering dummy shaft.
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    Fixture locating disc in place in the cylinder bore.
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    Dummy shaft in place, note shaft collars on fixture.
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    Spacer plate for camshaft to crankshaft centerline.
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    Shims in place before pore.
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    Heating up prior to pouring the upper bearings.
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    Preheating for the lower pour.
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    Babbittrite packed in place for the pour.
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    Shims in place for pouring the lower bearings.
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    Lower bearings after the pour.
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    Pouring the lower bearings.
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    Babbitt is poured until it fills the moat above the bearings.
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    Crankshaft in place. Pressure wedge chamfer just visible at top edge of bearing.
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    Back together and turning pretty.

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  • 08-06-029-P1010021.jpg
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  • 08-06-029-P1010048.jpg
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Anyone who has had the opportunity to watch an old-timer pour lead in a plumbing system or babbitt around a shaft knows that it looks deceptively simple.

But like any of the trades, years of practice and plain know-how are key to a successful outcome. While none of us will have the opportunity to gain years of practice, by reading the right resources, the craft can be duplicated well enough to bring an old engine or saw rig back to life.

For the last year I've been in the throws of a significant rebuild of a 5 HP hit-and-miss engine. Though the babbitt bearings looked good, once the camshaft gear and crankshaft were in place, a soft rumble of the gear set revealed that the bearings would have to be re-poured. The subject of babbitt pouring has been covered in the 40-year history of Gas Engine Magazine - November/December 1974, March/April 1979, September/October 1981, September/October 1983, September 1988, September 1990, December 1998, October 2000. But perhaps the readers will enjoy one more approach.

Getting started
I decided to make a fixture to accurately hold a dummy shaft in the correct position, horizontally, on proper gear center, on the cylinder centerline, and in correct side-to-side location. I also decided it was best to pour the upper caps first, remove them and then pour the lower bed bearings. This was done without removing or repositioning the fixture.



First, a fixture (Photo 1) to be located within the cylinder bore was welded and accurately machined in a Bridgeport. The discs in each end of the bore (Photo 2) are 1/2-inch thick and have about a 0.001-inch clearance to both the bore and the piece of turned, ground and polished (TG&P) steel bar the fixture is made from.

The large end of the fixture is the correct width for the space between bearings. It is desirable to make the fixture as accurate as possible, as this will reduce scraping after the pour.