Babbitt and Shim Question

[hardtimes]

Well I guess I may be the first to find out how long a engine will go with no shims. Haha. When going thru mine, I did order a pack of shims in case I needed them. After using plastiguage, it showed only one connecting rod needed shims but none for the mains. So, hope I'm good for a while. I also have 2 complete spare engines in case something were to fail or my rebuilding abilities were not spot on. Just in case.

No, you will NOT be the first , by a long shot ! And , you will most certainly NOT be the last. I have a short block, patiently awaiting , that was made up without shims in either mains and / or rods !

A lot of what has been said in this thread, is very informative and makes sense to me. For example, if your clearances are set correctly with poured Babbitt AND full pressure oil system, why wouldn't it work just as well as Babbitt inserts that are set correctly with full pressure. And, why wouldn't you be able to expect same service out of both, given that they are treated same, i.e.-good maintenance practices, maybe racing; normal driving mixed with hard driving at times ?
And, the idea that use of SHIMS (may) allow caps to 'walk' seems feasible, especially under todays use/conditions, i.e.-hard acceleration, high speed /high rpms ..to join traffic ,etc.. Whereas, no shims use means no shims to allow cap movement..no ? And the idea of steel shims that may magnetize and/or rub crank, seems plausible cause for not using such ?

Anyway, learned a lot here and thanks for that to all who participated. Long time ago, I learned that some old timer racers used no shims and must have put together near perfect engine clearances, as they ran more rpm and faster speeds than I want to go in a Model A/B engine equipped machines ! Do you suppose that these old timers knew something about shims/caps/walking causing them problems. IMO, they been there/done that,eh

I have a good B short block , in waiting, that has no shims and we'll see if it can take the heat

 

[Kohnke Rebabbitting]

Reading the above posts, there seems to be a deal of over-thinking going on. . You could re- babbit a motor without shims. You would simply then have no chance for re-setting the bearing clearance when they wear. When you have your main and big end bearings re-babbited, your chosen bearing man could install shims if you ask him to. . He would do this before boring the bearings.
If the boring is done incorrectly, the clearance will be either too big or too small. It is either right or wrong. Shims are not there to correct bad machining!
Its really not that complicated.

Tom, if you leave shims out on a babbitt job, there is a good chance you will hit steel in the caps, as they are less then a half circle.

And when the caps are filed, or leveled again, it just add's to the shim pac.

 

[Ron W]

Ok I'm gonna pose this question for Tom Walker & Ron W, in your opinion what causes Babbitt bearings to wear prematurely so as the clearances "unacceptable"?

Brent, I don't why you would ask such a foolish question. I do not understand your PMs to me. Why argue over weather or not shims were steel or brass? It does not help answer the original question. Your info on shims is great but incomplete. It does not say how many were used at each joint. If you remove all babbit from a rod and a cap,You will notice that the cap is not as deep as the rod when measured from the flat. The difference is the approximate thickness of the original shim PACK! I understand you like to argue but in doing so you are not always correct or contributing to the forum! Ron W

 

[Kohnke Rebabbitting]

I had a B block re-babbited specifically for a full pressure conversion. When discussing the job with the machinist, he pointed out that we could not use shims because they allow the oil under pressure in the bearing to leak, which defeats the object of pressurising the system. I have run this engine for 5years with half a dozen track races a year each year, and road miles in between, and it still holds 50 pounds pressure with hot oil.
Splash system is not affected in this way by shims.

Tom, the part about not putting in shims because of oil pressure , your machinist told you more then he knew!

Most engines we rebuild from 1950 on down have at least .006 to .008 thousandths shims in the mains, and rods that we bore and we cut the shims right along with the bearings, and they do not loose oil pressure of any kind.

You can put in even .250 thousandths or larger shim and not have an oil pressure leak. They have babbitt on both ends of the shim and are machined with the bearing. So the part line would be closed on each end, and a oil well in the middle.


If you would use steel shims in place of the Brass, you would Ruin every bearing you bored!

Herm.

 

[BRENT in 10-uh-C]

Brent, I don't why you would ask such a foolish question. I do not understand your PMs to me. Why argue over weather or not shims were steel or brass? It does not help answer the original question. Your info on shims is great but incomplete. It does not say how many were used at each joint. If you remove all babbit from a rod and a cap,You will notice that the cap is not as deep as the rod when measured from the flat. The difference is the approximate thickness of the original shim PACK! I understand you like to argue but in doing so you are not always correct or contributing to the forum! Ron W

Again, I sent you documentation to prove what I am saying is correct. If you still choose to disagree with me even after verifying it on the original blueprint, that is fine but my contribution to the forum is trying to ensure factual information is published.

 

[Tom Walker]

Herm, thanks for enlightening me, that makes a lot of sense.
Herm, if you melted the babbit out of a Model A main bearing, block and cap, which had not been messed with (ie filed or machined on the mating surface) and bolted the cap back on, what is the diameter of the hole?
Thanks, Tom.

 

[colin1928]

Herm, thanks for enlightening me, that makes a lot of sense.
Herm, if you melted the babbit out of a Model A main bearing, block and cap, which had not been messed with (ie filed or machined on the mating surface) and bolted the cap back on, what is the diameter of the hole?
Thanks, Tom.

Tom
1.6875
but I have seen many bored larger ??

 

[BRENT in 10-uh-C]

Tom
1.6875 but I have seen many bored larger ??

Yes, Colin is correct in that the minimum nominal size the caps were bored to was 1.687 but the tolerance allowed for the cap to be as much as 1.707, --this accounting for him finding larger sizes.


Now, to refute the idea that no shims would allow someone line-boring a block to "hit metal", look at this attached print. Using the centerline of the crankshaft with a .004" shim as specified (circled in Red), the Ford machine shop was to bore the cap to the internal diameter of 1.687 - 1.707. Now if an unaltered cap were installed on the block without shims, this would allow the babbitt to bored to 1.625 (.001" clearance on a Std. crank journal) and there would still be over .060" thickness of Babbitt at the bottom of the cap. This is substantially more thickness than 'one would find on many other engine insert shells lined with Babbitt from the 1940's thru the '60s.

Now, there is one other dimension given on this print to prove the babbitt was indeed burnished. My original prints of the crankshaft show the main journals were to be ground to a tolerance of 1.622" - 1.624". The print below specifies the babbitt was to be bored 1.618" - 1.620" (Noted with Green circle.). Now using the average of those two specifications, it is easy to surmise that inserting an object that is 1.623" in diameter into a hole that is 1.619" is going to create an interference.

While it specifies this on a yet a different print where the cap was bored in place with the shims installed, ...lets just suggest that the cap was to be bored separately, and later when the cap was install onto the cylinder case with the .004" of shims, this would bring the numbers to be the same. Even at that, you would have 0.000" clearance between the babbitt and the crankshaft. So if someone STILL chooses to believe that burnishing of the bearings was not done originally, then maybe they can show proof why Ford's engineers specified those interference-fit numbers.



.

 

[Kohnke Rebabbitting]

Herm, thanks for enlightening me, that makes a lot of sense.
Herm, if you melted the babbit out of a Model A main bearing, block and cap, which had not been messed with (ie filed or machined on the mating surface) and bolted the cap back on, what is the diameter of the hole?
Thanks, Tom.

I don't know Tom, as the Block is bored, and the caps are Rough. You just get it with in 3 or4 thousandths of round. Most of the time we use .032 thousanths to get it that way.

 

[Kohnke Rebabbitting]

Here is the problem with your prints, that is when the blocks were new, after 80 plus years, they are not.

The biggest concern is the cap not to close, and not to far away from the seal area on the crank, just like the Aluminum one in the block.

Do 3, or 4 hundred of those, may be you will get it!

The last thing on shims, NO car company's used steel shims in the bearings of there New engins, including Ford, The ones that were used were after the fact as steel is and was cheap!

If you want to use steel in bearings today, you won't even get it Align Bored with out Ruin of the bearing!

 

[BRENT in 10-uh-C]

Here is the problem with your prints, that is when the blocks were new, after 80 plus years, they are not.

The biggest concern is the cap not to close, and not to far away from the seal area on the crank, just like the Aluminum one in the block.

Do 3, or 4 hundred of those, may be you will get it!

The last thing on shims, NO car company's used steel shims in the bearings of there New engins, including Ford, The ones that were used were after the fact as steel is and was cheap!

If you want to use steel in bearings today, you won't even get it Align Bored with out Ruin of the bearing!

Herm, respectfully I do get it!! I am NOT saying you aren't a good machinist or that you are not a good engine builder however often times you give out information that just isn't factual. While you may believe that steel shims did not exist back then, nor were they used at River Rouge, I have personally seen them in very low-mileage engines I have worked on, AND the factory blueprint above even specifies the steel material. Others have seen them too, so how is it you continue to argue against what we know are the facts? Misleading others or trying to sway their opinion just because of your beliefs differ does not change the facts. This site has lost many knowledgeable people's participation over the last year or so just because of this very nonsense.

.

 

[darrylkmc]

Just an observation, I have mentioned this before, but here we go.

I have a three original engines, a 1930 Model A, 1932 B non-counterweighted crankshaft, and a Diamond Block B, the latter one I am running today.

All three are standard crankshaft engines with the original shim packs and standard bores.

All three have Steel Shims.

Darryl in Fairbanks

 

[40 Deluxe]

So what would cause a steel shim to become magnetized?

 

[James Rogers]

So what would cause a steel shim to become magnetized?

Steel is inherently magnetic all the time. I had a surveyor to prove this to me in the 60's when I was helping pull rod. He would not let anyone get close to the instrument with anything in their pockets that might disturb the compass. To make sure I remembered this, he took his pocket knife and passed it within 2 feet of the compass and it drew the needle out of orientation. All steel has some magnetism in it. As for the rest of this (shrug).

 

[Ron W]

The magnetism is in the compass, or did your pocket knife always point north? Ron W

 

[BRENT in 10-uh-C]

I don't know Tom, as the Block is bored, and the caps are Rough. You just get it with in 3 or4 thousandths of round. Most of the time we use .032 thousanths to get it that way.

Steel is inherently magnetic all the time. All steel has some magnetism in it. As for the rest of this (shrug).

Hey Mike, I guess I agree with you but if steel is a 'No-No' because the magnetism (that someone says would attract metallic junk and ruin the bearings), why did Ford use steel for the Crankshaft?? It would seem THAT would be WAY worse than a very thin piece of steel used as a shim. I guess I am just too new at this Model-A business to understand!

Also, since you are also one who "has done 200 or 300 engines", how often have you seen the main bearings in the block bored smooth from the factory yet the caps were unmachined and left rough?

 

[hardtimes]

Hey johnny,
Well , at least you got a succinct/straight answer from post #24, forever4 ! And , you got the rest of what is going on straight/succinct from Ron !
IMO, we all come here to hear from guys like you and the input about the situation you face and express. Surely, we come for input/opinions from ALL, but whether any input/opinion given....is FACTS, is debatable, informative and entertaining... most of the time ! Up to you to use your 'filter',eh

 

[Tom Wesenberg]

I think we may need to call in Wonder Woman with her trueth lasso.

 

[juke joint johnny]

Well Hardtimes Looks like we Rattled a few Cages on this one !!! 5 Star Thresd as Well
I'm worried Folks will be out with their Shootin Irons if it carries on.!!!

Just to set the Record Straight and to lighten things up
Are Wonder Womans Bracelets Steel or Brass or did you even notice she had Bracelets?!!

John Cochran

 

[Mitch//pa]

i voted for an excellent thread very entertaining..