The Stovebolt Site Forums The Shop Area Engine Shop 1949 Chevy 216 Bearing Advice

Bearing advice - While restoring my Chevy 216 engine, I noticed that the rear main bearing cap insert had a small crack. I've examined the remaining lower bearing caps and did not see anything unusual. However, several of the connecting rod bearings were damaged (on the piston side - not the caps). They were cracked and one was missing a small chunk of the bearing. I have not dropped the crank so I can't say what the upper main bearing inserts look like. The crank journals (for the main bearings and connecting rods) were flawless - all mains were round with uniform journal diameters as were the connecting rod journals). I will have the connecting rod bearings re-babbitted. I was told that the bearing damage was most likely due to high engine rpm. I now have a 3:55 gear ratio so rpm should no longer be an issue. But what should I do about the rear main bearing? Can I have the cap repaired (I think it's just an insert) or must the upper half of the bearing also be replaced? This job became far more than I expected and I'm a bit out of my comfort zone - thanks for any advice.

I'd suggest putting in a new set of main bearings. The damage to the rear main- - - -it is in the bearing, not the cap, right? Bearings come in sets. It's not possible to buy half a bearing, and it's highly unlikely you can buy single pairs of bearings. About the only way a vendor will sell you main bearings will be to buy the whole 4-bearing set. It's pretty simple to roll the upper bearing shells into place, so the safe way is to replace them. I'd reccomend removing the crankshaft, and at least get a machine shop to polish the rod and main journals, if it doesn't need to be reground.

Good luck on finding someone to re-babbit those rods. I don't think that's being done anymore. Federal-Mogul makes a set of insert bearings to replace the babbit in the rods, but the rods will need to be machined to accept the bearings. While the pistons are out, measure the cylinders for taper wear. If the cylinder is tapered more than .005", you'll need to rebore the block and install oversize pistons. Good luck!
Jerry

You ask about high rpm damage. I used to fix 216's in the parking lot while I was in college. The high rpm damage came from over revving in 1st and 2nd gear and missing gear. Wide open with no load, the dippers couldn't keep the babbits oiled. Even with a 4.11, I'm sure you would never drive like youngsters drove 50 years ago. By the way, why did you tear into the bottom end in the first place. Was it knocking, or were you just curious. There are places that still rebabbit rods, but it is expensive. Are you familiar with how to shim the rods and check them with plastigauge?" If not, you may have to try some old timer who still remembers these engines to help you.

I recently sent my 216 rods for machining for insert bearings to EGGE. They did a terrific job on on the rods.They will also do rebabbiting if you are willing to be patient.They are busy. www.egge.com

All great advice.

Drew - One last question - EGGE only provides a semi-finish which includes the machined oil grooves and/or oil pockets. They do not perform an ALIGN BORE to size the semi-finished bearings to accept the crankshaft. How did you handle this finish step?

The rods are fitted to the crankshaft using a tube of Prussian Blue and a bearing scraper, and LOTS of time! Spread a thin layer of blue on the bearing surface, snug the rod cap slightly, and turn the crankshaft a little. Tight spots show up as bright streaks on the bearing material. Scrape a thin layer of Babbit away at the high spot, spread more blue, and do it again- - -and again- - - -and again! It will take an hour or more per bearing to get a perfect fit between the shaft and the bearing, after which shims are added to establish the proper oil clearance. I've watched my father do this dozens of times, and I've done several rod-fittings myself. The insert bearing conversion is a lot less work, and nobody will know the difference unless the engine is torn down.
Jerry

Edit: I just looked at the Egge site, and the "semi-finish" they mention is for poured-in-place main bearings, like a Model T engine has. They say they can final-finish babbited connecting rods if you provide the crankshaft rod journal diameter. Hand-fitting with Prussian Blue is still the best method of assuring a perfect fit. When I worked for Standard Motor Parts in Nashville, Tennessee I machined stovebolt rods for insert bearings. John Rippetoe, Jr. is running the rod room now. Give him a call and he can probably do your rods quicker than Egge can. (615-297-1622)
Jerry

You’re right on Jerry as to the adjustment of the babbit. I just love to tell people when they look under the hood how easy these old trucks are to work on. What I don’t try to explain is that all things on them aren’t that easy to work on. Popin’ an insert bearing in and out sure beats scraping in a bearing and even after that’s done you really should check the clearances after it’s broke in.
And ya surely can’t go 100,000 miles on a tune-up or 5-10k on a lube job. But, it is easier to get at all of that that does need maintaining.
Denny Graham
Sandwich, IL

Jerry and Denny are both right in their advice and assertions.That's why I provided EGGE with my rod jounal size(s) and purchased the correct insert bearings from them to accomodate the rods and crank. As Jerry says, nobody will know I have insert bearings unless I tell them.

The insert bearings are a superior solution to providing a bearing surface, as compared to the babbitt directly on steel. My insert conversion worked out really well.

Thanks for all the great input about the bearings. If I was planning to drive this vehicle daily I'd absolutely get the insert job. But, as my annual mileage will be very low, I plan to go with original babbitt rods to spare the extra expense of buying the inserts. However, even as I read this I'm having second thoughts. Anyway, I feel mush more educated thanks to you!

As for getting the rods re-babbitted, I found a couple of places. Babbitting is a lost art and finding a qualified source was difficult. Apart from EGGE, Paul's Rod and Bearing in Kansas City MO has been very helpful and has years of experience with this type of rod.