The Stovebolt Site Forums The Shop Area Engine Shop how can I retrofit the non-dowel bearings on '54 235?

I've just been notified that my crankshaft for my 1954 235 engine has been finished regrinding. However, the shop couldn't source the dowel type bearings. So how can I retrofit the non-dowel bearings to this engine? Or does anyone know of a source for the dowel type bearings? ANY and ALL help/advise would be appreciated. And please remember, I'm NOT a machinist, so laymen's terms, PLEASE. ( Was told grinding was .10/.10)

S2

The late model main bearings (56-63, I believe) still have a dowel- - - -but it's only on the lower bearing that fits into the cap. The upper bearing shell has a tab at the parting line that fits into a divot in the block instead of a dowel, so an "in the frame" main bearing replacement is easier. The outside diameter of both bearings is the same, so buy the later bearings and use a 1/8" wide grinding wheel in a Dremel tool to make a slot in the block for the tab. It's about a 30 minute job for anyone with a few brain cells to rub together. Your "machinist" may or may not qualify! It's still possible to adjust the oil clearance with shims between the main bearing caps and the block, even with the later model bearings installed.
Jerry

Kick the bushes and get the right bearings. There is at least one set of .010 mains on ebay, likely more.

Quasi-related question. If you search RockAuto for 1962 - 235 main bearings, the results you get say something like “shim set ____” required. I was under the impression that the late 235s were not designed to be shimmed, certainly not “required” to be shimmed….even if shimming is possible.

Is RockAuto listing an earlier part that is incorrect? Or are the parts correct but they “shim required” language is incorrect? Or am incorrect, and you should be shimming 1962 main bearings?

It's called "lying". When the move was made to bearing shells with the tab at the parting line instead of the upper dowel, the shim adjustment was eliminated. Supposedly, the tolerances were tightened up enough that the shims were no longer necessary. If the oil clearance happens to be a little too tight due to an inaccurate regrinding job on the crankshaft, I have added a thin shim between the main bearing cap and the block to get things right. Just be sure the shim also overlaps the end of the bearing shell. We had to do that on one main bearing when we assembled John's 261- - - -There's a LONG story about that situation! The bearing doesn't know, nor care how it gets the proper clearance, but a too-tight bearing is a disaster waiting to happen. As always, common sense will always win over some slavish adherence to repair manual procedures.
Jerry

Here is the correct bearing set for the early model engines- - - - -with dowels on top and bottom. They also supposedly need the shim set. Sealed Power 960M, .010" undersize. Summit CLAIMS they're in stock. Given their habit of getting parts drop-shipped from the manufacturer, I have my doubts!

https://www.summitracing.com/parts/slp-960m10#overview

You might have to whittle out your own shims- - - - -the pre-cut ones aren't available at most places.

https://www.myautovaluestore.com/sealed-power/engine-crankshaft-main-bearing-shim-set-fed-fsm124s

Buyer beware!
Jerry

Can those bearings be modified to work in a 216 engine? Or are they a different width? I was trying to find .040 for my 49 and so far have not found any.

The #3 main bearing on a 216 is wider than the 235. It's the thrust bearing that controls fore-aft movement of the crankshaft. I have installed a full pressure 235 crankshaft into a 216 by widening the thrust face width of the 235 crank, and eliminated the Babbit bearing rods, but that also requires a different length connecting rod, or a piston with a shorter compression height. A piston for a Buick/Land Rover 215 V8 with the insert bearing 235 rods makes that conversion work, and the displacement of a stock bore 216 engine ends up at 224 cubic inches. It would be possible to narrow the #3 bearing web of the 216 and use an unmodified 235 crank with the late model 235 main bearings.

An Ebay seller called "Spark Surplus" has .050" undersize 216 main bearings. It would be possible to grind your crankshaft a little smaller and use them, but be forewarned that they're a bunch of donkeyholes to deal with!
Jerry

So the other bearings would work other than the thrust?