Babbitt Forever

P

PC/SR

Well-known member
Had to pull the engine to put in a new pressure plate and decided to check out the lower end while it was out. I hope these pics reassure those who ask if babbit can handle performance modifications.
This A engine has about 3500 driving and hillclimb miles and has been up to the 3500 to 4000 rpm range more than a few times. Oil system is stock except for pressure center main and a full flow filter, which pays off in the lack of any grooving in the caps or crank. I have also opened the dippers a bit.
The engine is fairly hot with HC head, cam, dual carbs, oversize valves, porting, headers, etc. Clearances are between .0015 and .002 using Plastigage with Herm's drop of oil method. Note the correct grooving and parting line wells.
My redline is 4000 rpm with this stock oil system. The engine is still climbing at that speed, but the oil system is inadequate beyond that range. NO problems with the babbitt. Folks should feel comfortable modifying the A engine and running it with babbitt for driving and hillclimbs. Pressure oil is needed over 4000 rpm.

Well, Will try again with the pics.
 
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Hope this has the pics.
 

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Interesting. Like many others, I thought modifications would wear out the babbit quite quick but this obviously proves me wrong.
 
Not to change the subject, but isn't the working surface of a "shell" bearing quite similar to babbitt? I'm glad to see that the original can hold up to some tough handling, obviously must be properly prepared and poured, them machined to tolerance. Sounds to me like you have an excellent job there.
 
Ray
I think it is put a drop of oil on the area that the Plastigage is put if working with a dry clean bearing/crank. Dry it will just press into the babbitt and not spread out like it should. A shell bearing has just a thin coat of babbitt with a steel back so dry will work.
MarkG
 
Can you tell me what the make up of your present babbitt is? Nickel babbitt? composition Antimony, copper, and tin contents?
 
Hey PC,
Thanks for that excellent report, pictures and input !
Is that the engine that Joe S. did for you ? If so, I'm glad for you and him :) ! Maybe this will blunt some of the naysaying regarding the use of properly poured babbitt engines, maybe not , eh.
I am happy that you did such good job reporting on this, as I'm putting together a poured Babbitt B that is prepared very much like this engine of yours. But, I am / was going off of talks with Jim B and his racing experiences at Bonneyville, etc, using poured babbitt B engines. I've also used his book as guide to help keep me on course. I'm thinking that with full pressure, I should be able to get at least same great use that you have expressed !

For those who ask questions about...why add a filter ? This should give these guys an excellent example, with pictures, of the benefits of adding a full flow filtration oil system.
 
700rpm said:
What is Herm's drop of oil method?
Click to expand...




I don't want to speak for Herm. But, Oil should be used when using plastigauge, it shouldn't be used dry. I have a feeling that those that don't like this stuff may not be using it correctly.
 
What I notice, and I am in no way saying anything is wrong here, with these caps.

The edges of the babbitt appear to be tight to the shell. This is an important thing to notice. If the babbitt is pulling away from the shell then it is not properly in the saddle. Now the center cap is tinned to the steel so it should be down tight, but the rear main needs to be looked at closely.

What I see in the picture, and the picture may be mis-leading. I see some areas that look shiny and others that are dull. Again pictures can be wrong. The different areas indicate the babbitt may not be fully contacting the main.
Now the question, if there are some areas that are touching does that mean they are too tight? The crank should be riding on a layer of oil.

Again I am not saying anything is bad here (in fact just the opposite). I am just hoping to bring up some deeper comments on analyzing babbitt from a used engine.
 
What PC/SR is showing is common. Used correctly and done properly babbitt bearings work just fine. After over 30 years of rebabbitting and rebuilding all types of prewar engines in both cars used on the street and vintage racing, I have yet to see one fail even after 20 to 50 thousand miles. Some of these engines used in racing we regularly tear down for inspection and the babbitt is doing just fine after many years of hard use and abuse.

One other thing to think about: Are the insert bearings that your engine has been modified to take going to be available in the future?? Will undersized bearings be available if the crank needs to be reground for some reason down the road??

I have seen this issue with engines modified this way before, when 20 years down the road the inserts are then obsolete and have become unoptainium. A number of engines so modified that have come thru our shop later had to be babbitted because the inserts bearings could not be found and we have had to make new custom inserts as seen below (before being babbitted) to replace the obsolete ones in some of these engines.

Part of restoration and preservation is to not do something that is not reversible down the road.

Inserts-III.jpg
 
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Thank you Herm, that is quite a compliment coming from you. Babbitt was done by Bill Barlow in Bend, Or.

KR 500, I do not know what composition Bill Barlow uses. I asked him once but do not recall precisely. As I recall, it was not far from stock.

Brother Hesekiel: The mods are pretty much described in Jim Brierely's book, 4 Bangers. Jim knows more about performance bangers than most people know about anything and he is quite willing to share his knowledge. He has given me a great deal of advice, tips and encouragement, which I very much appreciate. You can order the book direct from him at jimb4e4@gmail.com A bargain at $24.

Beyond that, and I know Jim B will agree, the key to a well performing engine, whether stock or modified, is precision building. As another guru says, measure everything, twice. Then check it again. You do not have to add performance stuff to go to 4K. The trick is keeping it all together and good assembly will accomplish that.

Kevin: The shiney part on the block, which I think is what you are referring to, is just light reflection. The babbitt is tight to the block all around. If you are referring to the dark "gap" between the block and crank journal, that is the parting line well and is correct. Those wells are often done wrong. The "gap" caused by the oil film is imperceptable. As noted, clearances are between .0015 and .002. Definitely use oil with the Plastigage. I let it sit for a couple of minutes before torquing down for the measurement.
 
thanks for the plug PC. i agree with you on the 4,000 limit although i know of one guy that turns his 4200 - 4400 on dirt tracks with oiling like yours. i turn my cook 6,000 - 6200 on babbitt but it is a full pressure system.
 
I think the regular barners should beware this post. You obviously had a meticulous babbitt pour done by someone who knows what the hell they are doing. We all know this kind of person is getting harder to find. Example, we have a local dude who has all the jigs to pour babbitt but does a crappy job regardless.

Sometimes you do not know ahead of time just how good/bad your babbitt job really is.

Based on the majority of babbitt jobs we have worked on here, most were good only for an ice cream run, never touring or high speed. If these folks turned 4K most all of them would have grenaded their motor.
 
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