Babbit Bearings/Insert Bearings When ?

[Jack Worstell]

The Buick Straight 8.......       when was the switch from babbit bearings to insert type for the main bearings ?    For the connecting rod bearings.

 

Jack Worstell

[Guest]

It has been reported that the first 5,000 engines produce in 1949 were Babbitt, then all inserts after that. I have not verified with documents. Everything in 1950 had inserts. The crankshaft journals maintained the same diameter, so you can retrofit later insert rods from the same size engine to replace the Babbitt rods. Terrill Machine in Texas modifies Babbitt rods for inserts, just under 400.00 using your rods! So, for sure the 1950 Special engine is supposed to be a 248" according to factory publications with inserts. If I sound a little dubious about committing to those specs it's born of experience. 1950 Roadmaster= inserts. 1950 Super new design 263" with inserts. More powerful and better mileage, oh oh, I'll be in trouble for that one! Maybe 1949 &  spec for 1950 for 248 inserts kinda narrows the availabuilty for stock rods. Hope that helps! Even more, hope it's close to correct!

Edited May 27, 2016 by Guest
Dim bulb! (see edit history)

[Ben Bruce aka First Born]

Jack, looks like you are new. Welcome

   Inserts on MAINS began back in the thirties sometime. As 2carb said, maybe some '48s had insert RODS. I believe all '49 and later RODS were insert. And they will exchange back to at least '40, maybe farther.

 

  What do you have and where are you??

 

  Ben

 

[Jack Worstell]

Thanks Ben and 2carb40

 

I'm helping my buddy with his 1937 Cadillac series 60  ( perfect sheet metal...no rust ever ! )

 

After this project.....he wants to find a 1937 Buick.....he grew up with 1937 Buicks and that is really his favorite.   He is shopping around and has spotted a few possibilities but wants to look further.

 

We are in Charleston WV      jlwmaster@aol.com

 

Jack Worstell

[MCHinson]

If your friend is not a member, he should consider joining the 36-38 Buick Club. We have some cars advertised on the website and also have some advertised in the Torque Tube II from time to time.  He can find the club website at: http://www.3638buickclub.org/

[Jack Worstell]

Matt......Thanks for the tip.   I downloaded the membership form and will send it in this week   

 

......I believe you are the gentleman who advised me that a 320 ci could not be squeezed into a 1937 Special ??   I would guess that the reason is that the larger engine is too long to fit into the engine compartment......would I be right ?

 

Jack Worstell

[MCHinson]

Yes, That is correct. I also just sent you an email as a result of one of your other posts. 

[nzcarnerd]

I hope everybody read this post   -  

 

[LAS VEGAS DAVE]

What about the main bearings and the cam bearings in a pre war 248, are they inserts? 

[70sWagoneers]

Mains and cam bearings are insert, Dave. I hate to have to get rid of the main inserts because they have a wonderful script "Buick" on the underside!

[Bob H]

1939 Series 40 main bearings: I have recently rebuilt my 248 CID motor which included replacing the main bearings. Research showed that the original main bearings were semi-finished shells similar to or actually "insert" bearings. Big difference, they were installed, the main bearing caps torqued down with a shim stack which allowed future bearing clearance adjustment, and the in place semi-finished bearings were "line honed" to fit.

 

The engine I was using as a core had been rebuilt at some time and started but never put into service. A teardown was necessary because water had got into one cylinder and damaged it to the point that it needed a sleeve. Good Thing. Among other things, the main bearings were incorrectly fitted. Whoever did the work installed later model finished precision bearing shells, with the shims! The modern shells did not have the proper crush fit and main bearing failure was imminent. Tried removing the shims but that bound the crank up so it wouldn't turn. The solution was to line bore the block and main bearing caps to fit the modern finished insert bearings, the result is a really smooth and free rotating crankshaft.

 

Can't say what years would have this arrangement but 1939 for sure. Bob H

[Jack Worstell]

I'm having trouble understanding the difference between  "semi finished"  inserts and  "precision"  inserts........can anyone elaborate ?   ( I'm assuming that a third type is the old "poured" babbit style which Buick had previously used )

 

Jack Worstell

[Bob H]

I'll explain the terms the way I learned them, there may be other interpretations. In this context, semi-finished main bearing  inserts that are factory finished on one side only, the outside diameter (OD) or side that fits next to the block and main bearing caps. The inside diameter (ID) or bore is manufactured with a surplus of bearing material so the inserts may be finished, after installation, to fit either a standard size crank or one that is ground undersize. These inserts were engineered to work with main bearing caps that are bolted down on a shim stack which allows for fine tuning to compensate for future wear. My understanding is that two types of main bearing shells were used in 1939, both the semi-finished and a finished style. Both of the original 1939 main bearing shells used shims between the main bearing caps and block for adjusting clearance.

 

"Precision bearings" is a term I picked up while learning my engine building skills, auto parts professionals in my part of the USA use this term. These inserts come fully finished and ready to use, Buick began using them in connecting rods sometime in 1949 I believe. Not so sure when they became the standard for main bearings. These inserts require slightly a different design for the block and main bearing caps. Precision inserts require an engineered amount of "crush" or pressure when they are assembled and the only way to take care of wear is replacement, no shims.  Originally the main bearing caps on my 1939 248 CID motor came with shims to adjust main bearing clearance, it had to be machined to accommodate the more modern fully finished inserts. The machining is not difficult or prohibitively expensive, any full service motor machine shop should be able to do it.

 

Stop by if you are in the neighborhood, Bob H

[jdd5345]

Hi Bob H,

 

I know it's been a while, but do you know the factory size of the shim stacks? Were they about 0.0035" on either side of the cap? My original 1940 248ci caps all seem to be lacking about 0.007" of height.

 

Thank you

[Larry Schramm]

I do not think it is so much the thickness of the shim stock as the clearance of the bearing to the rod.   I seem to think that the starting stack on rebabbitted bearings is about .125 inches.  Then you peel off shims as needed to keep the rod to c/s proper clearance.  Usually about.001"/1 inch of crankshaft diameter general guidelines.  Check the factory specs for correct clearance.