The Stovebolt Site Forums The Shop Area Engine Shop 216 main bearings

I just had my rod journals ground and by mistake they also took the mains down to .30, I already had it ground to .10, bought babbitt bearings and shimmed it. I had the rod journals just polished tring to get buy cheap, then learned they were out of round, and had to send the crank back. My question is do I really need babbit mains or can I use regular mains? I see non babbit mains for sale, and to me they would be better. In a previous post you guys helped me with rod bearings and recommended getting my rods machined for inserts, if the scoops are adequate for lubing the rods wouldn't the low pressure system be enough for the mains? Thanks for any help, as you can see I am not to smart with this stuff.

I think I am even more ignorant about these engines than I thought. Just the rods have babbitt bearings correct? I just assumed both were babbitt.

Correct.Just the rods.

Thanks for verifing that for me Drew.

Have you read the explanations in a Shop Manual? They offer a little information regarding the various bearings.

main bearings

oil lubrication system

The rods have integral babbitted bearing surface. Cam bearings are removable and have a babbitt bearing surface.

Main bearings are insert bearing with a babbitted bearing surface.

babbitt metal

Tim,yes,to be exact, what you link is specific that the bearings are of babbitt metal type.I think Tuley was more concerned about any machining process needed on the main bearings as per rods.

"My question is do I really need babbit mains or can I use regular mains? I see non babbit mains for sale, and to me they would be better. "

"I think Tuley was more concerned about any machining process needed on the main bearings as per rods."

Machining needed ON the main bearings?

My guess is that Tuley has learned that it is prudent to have all bearing surfaces checked and turned, if needed (a good machine shop should check them every time and let the customer know the conditions). After grinding/turning (and then polishing) the crank bearing surfaces on the crankshaft (rod bearing surface and main bearing surfaces), new rods with integral rod bearings are needed, and new insert main bearings are needed. All these bearing surfaces were made of babbitt material (on a 216).

Can anyone post a part number for "non-babbitt mains" and "regular mains" for a 216 engine? It has been 38 years since I rebuilt a 216 and I do not even pretend that I remember very much (but I dimly recall messing around with plastigage).

The 1942 Shop Manual describes the "machining" process for the babbited main bearing inserts for the early 216s. The 1948-51 Shop Manual says that with the new precision main bearing inserts machining is no longer required.

Are the part numbers shown in the Master Parts catalog for the pre-1948 216s for the "non-precision" inserts?

Hoyt

There was a discussion about this some time back. The advertising for 1948 Chev trucks talks about the new precision main bearings that can be replaced without machining them. According to a source at the VCCA, GM eventually came out with precision field replacements for the earlier 216s that did not have to be machined. I don't know how far back this goes but it would be 1947 and back.

You always have the choice of having the rods machined to take inserts. These are special inserts for this application.

Can you even get 0.030 under mains for the 216? Sounds like they ruined the crank.

Thanks for all the input, there is alot of knowledge here. I have found .30 under main bearings, I also ordered insert bearings and found a shop to machine the rods. And with the new cam bearings I had installed all will be modern non-babbitt bearings. I hope this will be fine with a splash/low pressure system. again thanks to all.