thoughts on main bearing Babbitt ??

[duke36]

anyone on the left coast pouring proper babbitt for a rear main cap ?

[old ugly]

I can’t answer that but a Babbitt guy most likely won’t pour just 1 bearings, I also only needed the rear redone and they refused to do just the one.
Lots of factors were told to me.

[Richard Knight]

As I said I am not going to argue with anyone. Look up the definition of a plain bearings. Seek out the scientific American magazine article on plain bearings. Interrupting the oil film IS A bad idea. The oil groove in the cap does interrupt the oil film. Nothing complicated here to understand. I am not telling anyone what to do. Either you understand or you don't. Not my problem.

[alexiskai]

Here's a (long) excerpt from SAE Transactions, 1926. You can read the entire paper here.

Effects of Oil-Grooves

Chairman Horning:—What has been the experience with no grooves in the connecting-rod bearing?
Mr. Sparrow:—Nothing was done in this test with reference to oil-grooves. Some experiments were made at the Bureau of Standards with bearings in which the presence or absence of the lubricating film was shown by an electric light, the circuit of which was broken by the film. That is a more or less qualitative method but, under certain conditions, there was a continuous light and, under other conditions, no light and a considerable region in between where intermittent flashes occurred. A number of bearings were tested under such conditions as regards speed and load that there was no light, proving that there was a complete oil-film. Each of those bearings was then grooved in one way or another and, under those same conditions, they showed continuous light, indicating bearing all the time and proving that the groove did destroy the oil-film. In making a statement of this kind, however, the fact should not be overlooked that there may be a need for some type of groove to take care of the dirt which comes through the bearing; that is, something of the kind may be needed to permit a sort of flushing action. With a crankpin which is drilled with a large axial hole and a small hole at right angles to it for feeding the connecting-rod bearing, I think everyone has had the experience that when the plugs are taken out from the end a considerable accumulation of foreign matter is found. Some of the dirt must go through the bearing, and it is entirely reasonable that some channel to take this dirt out directly would be advantageous.

Chairman Horning:—It is important to note that, without oil-grooves, it is possible to get complete lubrication in these tests and, under the same conditions with oil-grooves installed, the lubrication is intermittent. The other point Mr. Sparrow makes is that the groove may afford great advantage in getting dirt out. We had trouble with a camshaft front-bearing having 0.0015-in. clearance. Remembering the direction of flow as indicated in the glass journal with which Mr. Barnard experimented, we made a groove and then were able to feed dirt into that bearing and throw it out again without any difficulty.

Mr. Barnard:—Occasionally a bearing in an internal-combustion engine depends entirely for its oil supply on the oil-flow from the supply tube and does not receive oil from the ends of the bearing. Consider, for instance, a bearing 2 in. in diameter. There is about 1 ft. of clearance space open at the ends for oil to get out. If no oil-groove is present, there may be only about ¾ in. or possibly 1 in. of clearance space at the perimeter of the oil-hole for oil to get in. We think it may be better to put an oil-groove in a bearing to supply area for oil entry which is at least comparable to the effective area available for oil escape, on the theory that it is better to build-up an oil-film and destroy part of it than not to supply sufficient oil to build-up the film at all.

Chairman Horning:—Has anyone a practical suggestion as to a successful attempt in using a bearing that has no oil-groove?
A Member:—The Rickenbacker Big 8 has a groove milled in the shaft. There is a longitudinal groove along the crankpins which acts as a spreader to get the oil out along the bearing. An end-mill cut is taken along the crankpins such that a section of the pins becomes a circle with a portion of a segment removed. The intersection of the chord of the segmental portion removed and the arc representing the bearing surface is on the trailing side, as I recall.

W. R. Strickland:—Discussion with regard to plain bearings should carry a factor for production, especially on new jobs. It is difficult to get the oil into the bearings when first fitted-up if no oil-grooves are provided. Further, after an engine has stood a long time the oil runs out of the bearings and, when the engine is started, an immediate supply of oil to the bearings is needed; oil-grooves are often installed for this purpose that are not necessary after the engine gets under way and the regular supply of oil reaches them.

Chairman Horning:—During the war when we were designing the Class-B motor-truck engine we decided to use a force-feed system of lubrication and then the question came up as to what oil pressure should be used. Pressures from ½ lb. up to 100 lb. per sq. in. were advocated and therefore we thought there must be some common factor. We came to the conclusion that no matter what their oil pressures were, all the engines using force-feed lubrication required about the same amount of oil per minute; in other words, the common factor was about 2½ gal. per min. past the bearings in a four-cylinder engine. The difference between the engine having a pressure of ½ lb. and those having a pressure of 100 lb. per sq. in. was due merely to differences in the oil-grooves. The engine with a pressure of ½ lb. per sq. in. had a bearing that was all oil-groove, and the one with a pressure of 100 lb. per sq. in. had hardly any oil-groove; so, by determining the common factor and utilizing it, we developed a successful engine. If any one subject should head the list of requirements for practical engine designing, lubrication is that subject.

Effects of Over-Oiling

A Member:—What has been the experience with over-lubrication resulting from pressure feed to the wristpins of an engine? In 1917 we had a Buda motor-truck engine which had pressure-feed lubrication to the wristpins and we never were able to obviate smoking cylinders until we closed the tube leading up the connecting-rod. No serious wear on the wristpins resulted, owing to the fact that the rod had on its top a spot-faced hole which allowed the oil to drip down into the top of the rod. That cured the oil-smoking trouble.

Chairman Horning:—The tube running up the connecting-rod on the Buda engine was a device imposed by the War Department to assure adequate lubrication at the front in the war. It has been conceded generally that very good results can be obtained by taking oil from inside the crankcase, or taking some oil off the cylinder-wall. With the piston-rings that are in use at present, I think there is very little difficulty due to over-oiling. On the other hand, I agree with the remark made previously that it is better to over-oil and wipe the oil off than to under-oil.

Dr. Dickinson:—Chairman Horning has made the point about the importance of the oiling problem, and there is no question about it. Still, there is a rather amusing phase of the whole discussion to which I would like to call attention. One very successful engine with which I had to deal years ago ran very well with 4 drops of oil per min. to each journal. Another engine required 2½ gal of oil. This is a wide difference between successful engines. Chairman Horning mentioned oil pressures all the way from ½ to 100 lb. per sq. in. There is room for plenty of work on the lubrication problem to see if we can determine some common factor which will serve to correlate such extreme discrepancies between the oiling systems of successful engines.

Chairman Horning:—Illustrating the extreme importance of oil, an engine used on certain motorcoaches ran 50,000 miles without having the bearings tightened. Then the company adopted a very effective air-cleaner and the engine ran 100,000 miles. Later, an oil-cleaner was adopted and the mileage increased to 150,000 miles. The company also uses a large-capacity oil-pump. In heavy-motorcoach service many failures have occurred by there not being enough oil delivered to the bearings at the higher speeds, or because some bearing is getting too much and some bearing is not getting enough. Many four-cylinder engines formerly had their camshafts lubricated by the splash system. If with the same oil-pumps oil is fed to the camshafts, a reduced quantity reaches the main bearings. With a four-cylinder engine, having main rods and three camshaft-bearings, there are 10 outlets altogether. Adding the idler-gear bearing to be lubricated makes 11 outlets. In the six-cylinder engine there are 19 outlets. Many of the early failures in engines were due to adding outlets and retaining the same size of oil-pump.

Mr. Oldfield:—An engine having drip-feed lubrication was very successful in motor-trucks abroad; it ran an average of 125,000 miles between overhauls.
Chairman Horning:—That was the Albion engine, used during the war by the British War Department. The Department published a series of observations on these engines after certain periods of service. The Albion engine had a very intricate system of feeding oil one drop at a time or a certain number of drops per minute. The engine had about a 4¼-in. bore and about a 5-in. stroke. The diameter of the connecting-rod bearing was 1½ in., which we would think insufficient in these days, yet the Albion engine had the best record in the British Army. Its lubricating system provided clean oil, having no dilution and no dirt in it. That engine, with that exceedingly small shaft, showed less wear than many shafts having 2¼-in. diameter and ample length.

[BRENT in 10-uh-C]

Colin thank you. Irony is this was discussed prior to the Model-A engine even designed. Additionally, the Abstract is an interesting read however much is apparently unknown and so they are simply getting collecting opinions. Kinda sounds like Political Polls taken in our times, doesn't it. It just depends on who you poll.

Furthermore, these guys that are debating this are long since passed, and just because they called themselves Engineers does not always prove they are accurate about what they debate.

I have no desire to debate Rick in this either because it is pointless. I do not know of his qualifications as to whether he even has experience casting Bearings by which he (-and/or his customers) can share firsthand experiences with Model-A engines with specific regards to grooving, -or whether he has learned all of his information behind a keyboard.

[alexiskai]

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This reminds me of a quote from another article about the same time:

“G. A. ROUND — Why is it that, in spite of the fact that the oil is applied on the wrong side of many crankshaft bearings, the units still run and have run for thousands of miles without giving any particular bear-ing-trouble?
MR. BARNARD — That is just an illustration of the enormous carrying-capacity of a thin film of oil.”

I think it’s hard to get a definitive answer on this issue because multiple oil groove designs can work in an engine for a long time. And when it does wear down there will always be alternative explanations for why it did: insufficient filtration, crank flexing, etc. None of these designs are overwhelmingly superior to the others.

[Richard Knight]

I agree with Brent, there is no sense arguing. Either you consider there may be an alternative to the factory grooving or not. I am certainly not telling anyone else what to do. I am stating what I know to be true and worked for me.i can assure you I am not a key board warrior. At the age of 77 my experience goes back to 1961 when I went to work in a small engine shop at the age of 13 which required a work permit. Having a model A needing new main bearings in the mid 60s my dad made the molds and found a universal boring bar. I hand cranked that boring bar more than I would like to admit. Once word got out that we could Babbitt and line bore. The first job for someone else was 1965. That lead to a complete automotive machine shop in the 70s in an industrial park. Yes I have poured a few hundred pounds of Babbitt and lined bore 200-300 fords. But I worked on all brands and all years so my experience is very deep. I could go on ad nauseum but won't.

[BRENT in 10-uh-C]

Originally Posted by alexiskai

This reminds me of a quote from another article about the same time:

“G. A. ROUND — Why is it that, in spite of the fact that the oil is applied on the wrong side of many crankshaft bearings, the units still run and have run for thousands of miles without giving any particular bear-ing-trouble?
MR. BARNARD — That is just an illustration of the enormous carrying-capacity of a thin film of oil.”

I think it’s hard to get a definitive answer on this issue because multiple oil groove designs can work in an engine for a long time. And when it does wear down there will always be alternative explanations for why it did: insufficient filtration, crank flexing, etc. None of these designs are overwhelmingly superior to the others.

Exactly Colin. No one is going to agree to what the longevity expectation of a cast bearing in a Model-A is supposed to be either. Many tend to argue why an insert bearing in a Model-A engine is superior because they last longer than what cast bearings do. When I ask how long they expect an insert bearing conversion to last, the conversations almost always turn into stories much akin to how big of a Fish was caught. "Well ole so-and-so only got 5,000 miles out of Babbit bearings but he got 20,000 miles out of inserts!". Hmmmm, so he only got 20k out of inserts but several Model-A owners I know have over 30K miles on their Babbitt bearings and there still going strong. Well yeah, but they probably don't have a high-compression head on theirs! You see, my friend wanted to drive his Model-A and it be reliable, so he switched to insert bearings so he could 'Tour' with his. Ohh, ok, I see!!! In my line of work, I suppose I have about heard it all!!

FWIW, -I even remember back in the 60's as a kid when several of the club members wanted a 'B' engine in their Model-A so they could drive faster and go longer. Dad's '31 Roadster and Bill Coleman's 30 Coupe (-both with Model-A engines) showed taillights to many of those A's w/ Model-B engines when we were on our way home after a tour. I can't speak for Bill's engine but Dad's engine was a 0.125 overbore A with a milled Police head, and a NOS Model B Camshaft. Dad never told them anything other than it was a Model-A engine. So, ...when we are being transparent, nothing has really changed in those 65+ years with Model-A owners!!

[Synchro909]

Wow, When I made my comment in post #13, I didn't expect to trigger such a long and in depth discussion. I have read it all with interest.