Babbit Bearing Questions

A

ALJ

Member
This is my first time to take the pan off and look at the rod bearings in my 28 Model A Coupe. I need some advice. The reason for dropping the pan was what I thought sounded like loose rod bearings. Rod bearing clearances, using plastigauge, are about .002 in. The spec I believe is .001 in. There are no shims on the rods. The question, is it OK to file the bearing caps enough to bring them into spec? If so, what is best to use, a file or course sand paper?

I haven’t looked at the main bearings yet. Maybe this engine is due for new bearings and a rebuild, although I would like to delay that for several months if possible. What are the pros and cons of inserts compared to poured babbit bearings?

The crankshaft journals show a few light colored milky looking spots. Is this a sign that coolant has been in the oil?

Comments will be appreciated. Being a newbie, I have found the comments here on the Barn to be very valuable.
 
I do not think .002 is loose enough to cause a noise. If you do want to tighten them up a bit, the caps can CAREFULLY be filed. The caps should have shims but occasionally, you will find bearings being pored without shims. Do not go too far as .001 is not much.

If the mains look OK or are just a little loose and can be adjusted, the engine may last a lot longer before it needs a rebuild.

There may be something else in the engine that is causing the noise.

My opinion,

Chris W.
 
I'm not in favor of filing the rod caps but if you insist I would run the caps over the top of some sand paper on a flat hard plate. This may get you by until you get the engine rebuilt.
 
Hi ALJ,

FWIW: I could be incorrect with an assumption; but, just one humble opinion.

Like Chris, 0.002" is not that noisy.

A more detailed elaboration on the 3rd paragraph:

"The crankshaft journals show a few light colored milky looking spots. Is this a sign that coolant has been in the oil?

appears far more important to check than 0.002" clearance which is not that much of a concern.

We men patients usually spill the beans and tell a pharmacist "all" of our medical problems when getting over the counter medicine or advice ...... but ..... we do not always elaborate on that much detail to our physician ...... maybe for fear of the worse news .... and/or being hospitalized.

Women usually tell everything to doctors and mechanics. LOL

What did the oil look like when you drained it?
 
sounds like you've had a bit of water in the crankcase as well, but if it's set a while it could be condensation. Change the oil and check after driving a while, see if it still persists.
 
Filing the caps make the holes oval. Look and see if they have been filed already. Measure the side diameter and compare to the vertical.

It is better to have non-filed caps if you are going to get the bearings babbitted.

To tell if they are filed look at the machine marks. The original machining was circular if I remember correct. File marks are odd straight lines. Lay the cap on something very flat and see if it rocks or has gaps.
 
Hi ALJ, Welcome to the Barn, and welcome to the A hobby! I am going to have to agree with Kevin above here. A rule of thumb when dealing with an antique car is: "don't do anything irreversible that you may wish to restore to original condition in the future." Your car probably had shims in the past, and these were probably removed to account for wear... If all you are dealing with is a measured clearance of 0.002 inches, I would look elsewhere for your "rod noise". Check the wrist pins in the pistons - if shims were removed to account for big end wear, it is possible that the small ends could have excessive wear as well.
Now, one exception: While I personally favor poured babbitt bearings, it is clear that the rebuilding trade is moving toward insert bearings. If you choose this route, you will modify the block in an irreversible manner...

PS I think you probably have a little drive time on this engine before you have to rebuild it. Does it smoke? Run clean? Good Luck and Happy Motoring!
 
If you carefully file the caps to where you have .001 to .0015 clearance and the babbit looks good go for it because if you find later you might have to replace the rods before a fresh babbit pouring there are plenty of good used connecting rods available. Besides removing .001 or .0005 from the caps is not going to cause much distortion. Just be careful to not over do it.
 
I will carefully file the caps to .0015. From the comments received I probably wouldn't need to do anything but since I have the caps off anyway, I will do it. I now have reassurance that I don't have an impending disaster.

Regarding the milky looking discoloration on the journals: The oil did not show any obvious water content. I suspect there has been some water or coolant in there at some time. I will continue to watch.

Thank you to each of you who made a comment. I appreciate the time that you experienced guys take to help us new guys. This is a fun hobby, and the Fordbarn is a wonderful resource.
 
I would not file I would use sand paper on a piece of glass sitting on a work bench!
Work your piece in a figure 8, oil and 320 paper, go easy, measure twice :-)
 
Hi ALJ,

FWIW: According to the vintage mechanics I knew who had great reputations for very precise mechanical work, Reply #10 Method was the "only" recommended method for car owners to remove metal from caps.

I always used this same method successfully ...... it was used often and successfully years ago.

For non-believers:

1. Get two (2) pieces of a wood 2 x 4, each cut 1-1/2" wide x 2-3/4" long and verify initial wood thicknesses at the four (4) corners of each.

2. Remove wood from one with a file; and remove wood from the other with a piece of glass and sandpaper per Reply #10.

3. Finally re-verify thicknesses of the (4) corners of each to "see" which method removed wood "uniformly" as opposed to removing more wood from one corner than the other which in the case of a bearing cap will cause "binding" on one corner.

Will Rogers always had it right:

Some can learn by reading, some by observation, but "most" have to pee on the electric fence to become believers. Trying the wood block first is as good for learning as peeing on the fence.
 
I would recheck the clearances again before doing anything. Make sure you're placing the plastigage correctly, and torqueing your rods to the proper specs. Then I would do it again with the plastigage going across the other way, again going by the instructions for plastigage. Read about the machining requirements for using inserts before you make a decision on that.
 
Basic reminder for Plastigage: Do not tap on the rod bolts to get the cap back off when checking with Plastigage on the crank. This flattens the Plastigage more and gives an incorrect reading. My brother-in-law did this years ago on a six cyl.
chevy. He had a .010 under crank but was given std. inserts by mistake. When he did the Plastigage he tapped on the rod bolts to get the caps off. The Plastigage said he had perfect clearances but boy did that engine rattle!
 
Hi ALJ,

If you ever wonder how billions of Babbitt bearings were very "accurately" adjusted with precision prior to the end of WWII, going back to the mid 1800's without the more modern Plastigage plastic material method, you may or may not want to experiment with this very quick time saving vintage Babbitt bearing adjusting method.

1. First, wipe off excess oil from Babbitt surface and wipe off excess oil from journal on crankshaft with a clean rag.

2. Install bearing cap with shims and check first for "up & down" bearing movement by "feeling" for up & down movement.

3. Remove shims until "no" up & down movement can be "felt".

4. At this stage, connecting rods should be easy to move from left to right, or as a minimum, with a very slight drag .... if no easy side to side movement, add "thin" shims until side movement is achieved ....... but, after achieving side movement, maintain absolutely "no" up and down movement which can be "felt".

5. After experiencing adjusting about the (3) connecting rods this way, you will learn to experience that vintage "feel" and remember it the rest of your life.

6. After acquiring the "feel", if one wants to conduct a "Test" and try the more time consuming modern Plastigage method, one will find that the adjusted bearing with the "feel" method is "Right On".

7. And, you will never have to pee on an electric fence to see whether or not this vintage method worked.
 
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Shim stock is the most ACCURATE way to check bearing clearances, or FOIL, if you must-------------------or a piece of AL-DENTE' Angel Hair Pasta.
Bill W.
 
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X2 what 700rpm said. Without accurate initial measurements you are just guessing. Once you start sanding caps there is no going back. Use oil on the Plastigauge. There a many threads on correct use of Plastigage.
 
There was no aluminum foil in the old days either ...... when millions upon millions of Babbitt bearings on steam and gasoline engines were correctly and successfully fitted by "feel".

No doubt Plastigage probably came out after humans lost their "feelings". LOL
 
H. L. Chauvin said:
There was no aluminum foil in the old days either ...... when millions upon millions of Babbitt bearings on steam and gasoline engines were correctly and successfully fitted by "feel".

No doubt Plastigage probably came out after humans lost their "feelings". LOL
Click to expand...
But, H.L, there WAS shim stock, used WIDELY:) Using shim stock can get the bearings adjusted "quite closely & quite uniformly." If you want them better than that, it's time to consider Insert Bearings.
I've known of engines going to POT, after an attempt to "adjust" the bearings, using "questionable" methods & ending with problems, such as, still a knock, or too TIGHT to turn the danged thing & sometimes ended in sending the engine to a professional for a rebuild. Chief would "collect" engines, ruined by their owners, rebuild them in a decent manner, use them in cars he was "building" or sell them, so we could EAT! Times were TOUGH! He also collected many useable parts, from the scrap bin at the local Ford Dealership, owned by his friend, Bill Ogan.
Bill W.
Adjusting by feel, or other such methods, was usually a desperate attempt by poor folks, just to get it "BACK ON THE ROAD, AGAIN."
Bill W.
 
Hi ALJ,

If you would like to try or not try this "feel" comparison Test listed in paragraph #6 above in Reply No. 15, you could also later "read" about this most trusted method of adjusting Babbitt bearings by "feel".

Ford addressed this proven method for years for professional mechanics in his Model T Service Manuals, and in paragraph 386 accompanied with a diagram of same in Figure 237 in the latest edition.

This method was used all through the 1920's and thirties by my Dad and his brother, as well as many other professional mechanics and machinists that I knew years ago.

It was not only successfully performed on Fords; but also all other makes of cars as well as vintage Lockwood Ash & Fairbanks Morse engines and steam engines.
 
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