The Stovebolt Site Forums The Shop Area Engine Shop Connecting rod bearing clearance for insert-rods

Hi All,

When inspecting the bottom end of the 216 I'm planning to swap into my truck, I was pleasantly surprised to find the rods had already been converted from babbit to inserts.

When considering adjustment of the babbit rods (should move when tapped lightly with an 8 oz hammer), how should I interpret the freedom of movement of the converted-to-insert rods?

Thanks,

Bill

Federal-Mogul lists the clearance for insert-converted 216 and 235 rods at .0005"-.0026". I use green Plastigauge and shoot for a .0015" clearance range. Ignore the "tap it with a hammer" advice- - - -there are much more accurate ways of checking clearance, and Plastigauge is the simplest. There's also a method involving using a small piece of shim stock between the bearing and the crankshaft and shimming until you get a "firm drag" as the crankshaft is turned, but it takes hundreds of rod adjustments to develop a feel for the right amount of drag. That's how it was done before Plastigauge was invented in the early 1950's.
Jerry

If you don't have any shims on the rods at present, you don't have the ability to adjust them. Usually the conversion is done so that the completed rod won't use shims.

Agreed- - - -we would usually machine/hone the rod conversions to a specific diameter without shims in place. With the rods torqued to 35-45 ft./lbs. the rod bore should be 2.4030"-2.4040". That should allow the insert bearings to run the proper oil clearance. If the clearance exceeds .003" the bearing is worn out and should be replaced. Insert bearing are currently available in .010" and .030" undersizes. The .020" undersize bearings have been unavailable for a long time. My friend who runs a machine shop has been searching for .020 under 216 bearings for a couple of years with no luck whatsoever.

Rod bearings for a Massey-Ferguson Diesel tractor (Perkins engine) can be modified to work in a 216 and they're available in all the normal undersizes. There are also Komatsu and John Deere rod bearings that can be adapted to 216/235 splasher rods.
Jerry

The rods don't have shims. It looks like I need to take some measurements (confirming rod bore and crank pin diameter).

Thanks for the help.

Bill

Hi Folks,

A follow-up question:
The spec for the pin diameter is 2.311/2.312"
A 0.010" undersize would be 2.301/2.302

The specs for the proper undersize bearing (SEP 1415SB10) note that it is 0.010" undersize and for use with a 2.312" shaft.

So, should that spec be interpreted as ").010" undersize for a 2.312" nominal shaft", ie "for a 2.302" shaft"?

The nomenclature can be a bit confusing.

BTW, my rod bores are confirmed at 2.403" and my rod pins are at 2.301/2".

Thanks in advance for the help.

Best regards,

Bill

Yes, you need an .010" undersize bearing. Fortunately, that size conversion bearing is still somewhat available- - - -expensive, but still in stock at most suppliers. The .020 under bearings are just about nonexistent.
Jerry