The Stovebolt Site Forums The Shop Area Engine Shop 1951 216 Babbet wear analysis help needed

I have pulled my rod caps on my 216 to inspect connecting rod journals and rod/cap babbet surface condition. As far as I can tell there is little to no babbet remaining.
Inspection revealed NO shims on rod caps, and only a slightly greyed surface of the rod cap and rod lower end. I cannot determine babbet from steel rod/cap material. There is a grooved oil channel approxamately 1/16th of an inch deep on both end cap/rod end is this groove cut into the babbet or the steel component material? Does anyone have clear close up photos of these babbet lined surfaces "worn beyond limits and new condition" Please forward to me at [email protected] or post please. Thanks.

The oil groove is in the bearing surface.

Take your micrometers and measure the rod and the bearing at several locations around the diameter . Tell us what the difference is.
If you dont have the mics then you will need to go to an engine rebuilder for proper inspection as just looking is not enough.

Get some plastigauge from a bearing supplier and lay a strip on the journal and torque down the cap. If it shows more than .003" with no shims then the bearings are too tired to re use.

Curt B.

How does the crank look? While you've got your mic's out you're gonna want to check the jounals for taper & out of round conditions. You'll want a good one for this, one that reads in 'tenths' (to four decimal places).
Doug

I can share some insight. When I pulled my 51 216 apart, there were dropouts in the rod babitt and you could see the height difference in where the babbitt was missing. Now, these rods came from the factory with something like .004" shims on both sides. If you have no shims in there then there must be some wear on those rods. Plastigage will give you an idea of the existing clearance. I would also say that if the clearance is greater than .003" then you probably would hear a knock.

I'm not suggesting that you do this, but I filed the caps on more then one of the old 216 stovebolts years ago and did not have the money to rebuild them properly, and ran them a long time
Cleon

Interesting replies, especially the posts regarding the rod babbet bearing clearances (.003 or more = excessive). The manual however does not specify an actual rod bearing clearance specification, only a measurement of no less than .004 and no greater than .012 between the connecting rod upper bearing half and the crankshaft journal throw (side to side clearance "slop"). I guess the actual specifications for rod bearing clearance is:
1.Broken rod potrudring threw the block = rod bearing clearance excessive.
2.Rod bearing surface scored,smoked,and friction welded to crankshaft journal with broken rod shaft = rod bearing clearance to minimal.
Either way = OUCH!

The first thing to do is measure the crankshaft journal for diameter, taper, and out-of-round. If it's OK on all the rod journals, move on to checking the oil clearance. I prefer to use a piece of shim stock between the rod cap and the crankshaft, about half the size of a postage stamp. Insert a piece of .002" shim, torque the rod bolts, and try to rock the crankshaft a few degrees by grabbing the flywheel and pulling it back and forth. Don't force it to move, just give it a good grunt. If the crank turns freely, substitute a piece of .003" shim, etc., until you get a firm drag or a lockup. When the turning effort increases noticeably, you've found the clearance. Repeat for all six rods.

Om the oldtime reconditioned rods, we would coat the crank or the rod with Prussian Blue, and snug the rod against the crank. Turning the crank would reveal tight spots, evidenced by a bright scrape mark in the Babbit. A bearing scraper or a sharp pocketknife was used to scrape away bearing material until the rod exactly matched the shape of the crankshaft, evidenced by a smooth smear of bluing without bright marks, then shims were added to establish the proper oil clearance. Fitting babbit rods is fun!
Jerry

Will,,,,if all shim,s are gone you have no adj left if you are on tight money or just want to save as long as pos use plasti gauge and file rod caps or look for a 235 1954 thru 62...doc