Adjusting rod bearings

[mrtexas]

Someone have a good procedure for this? I haven't done it before.

[Patrick L.]

A good procedure ? I don't know of any other than the way to do it.
I use plastigauge, then remove as many shims as it takes to get the clearance to .0015". I try to keep the shim thickness the same on each side, but, its not really necessary.
I don't have much luck peeling the shims apart, so, I just measure the pack thickness and then sand to the thickness I want.
I've also found that the rods don't really need adjustment very often. Its the mains that require attention, especially the center and rear. It'll take a special made wrench/socket to get at the rear. I just weld a socket to an old wrench or piece of flat stock.
Now, some of the fellas will tell how to do the 'foil' method. .001" thickness of tin foil should allow the crank to turn while .002" thickness's will not. Just remove shims to get the desired clearance.

[Joe K]

Patrick L has it just about right. I will mention though that you want to do ONE rod bearing at a time - and leave the other rods disconnected. Especially so using the foil method.

Also do yourself a favor and measure those rod bearings with a micrometer for egg shape. More than about 0.0015 and you'll find the rods "bind" at certain parts of the rotation - and limit how close you can bring it.

Joe K

[Synchro909]

I definitely would NOT use plastigauge! Far better (and cheaper) is a piece of newspaper or paper from a phone book. This paper is about 0.002" thick. Cut a piece just shorter than the width of the bearing and about 3/4" long. Soak it in oil, put it in the bearing and torque it up (after loosening all bearings so you are only dealing with one at a time). Now try turning the crankshaft. If it is locked, the clearance is ok and the paper will have had the oil squeezed out of it when you open the bearing. If it is still possible to turn the shaft with your hands, there is too much clearance. Remove shims and repeat till the shaft is tight but still possible to turn with your hands with the paper in. You will soon get to know how many shims to remove by looking at oily the paper still is when you undo the bearing cap. Lots of oil = wide clearance. Paper squeezed dry, tight. Ideal is evidence of the paper being squeezed but not dry - just a little wet with oil.
Leave the bearing you have just done loose so you have a good "feel" for the next. When all are done, tighten them all to the appropriate tension (35ftlb on the big ends and 45ftlb on the main bearings) and check the shaft for "drag". You should be able to easily turn the shaft with your hands.

[RonC]

plastigauge works good. For some reason the supplier catalogs don't mention you have to heat the shims first to peel. To split the peelable shims apart, lightly
warm them with a propane / map gas torch. Don't over heat them to much just enough for them to come apart. The shims can then be easily split apart.

[Patrick L.]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by RonC

plastigauge works good. For some reason the supplier catalogs don't mention you have to heat the shims first to peel. To split the peelable shims apart, lightly
warm them with a propane / map gas torch. Don't over heat them to much just enough for them to come apart. The shims can then be easily split apart.

Yep, Plastigauge does work good, and, its cheap.
I've only adjusted these bearings on a few engines, but, have not had good luck splitting them as mentioned even with a little heat. But, thats OK. I've also run across some that have solid shims, or, at least they were solid to me.
Doing this for the first time while the engine is in the car is a real, never forgotten, experience.

[Brendan]

Originally Posted by Synchro909

I definitely would NOT use plastigauge! Far better (and cheaper) is a piece of newspaper or paper from a phone book. This paper is about 0.002" thick. Cut a piece just shorter than the width of the bearing and about 3/4" long. Soak it in oil, put it in the bearing and torque it up (after loosening all bearings so you are only dealing with one at a time). Now try turning the crankshaft. If it is locked, the clearance is ok and the paper will have had the oil squeezed out of it when you open the bearing. If it is still possible to turn the shaft with your hands, there is too much clearance. Remove shims and repeat till the shaft is tight but still possible to turn with your hands with the paper in. You will soon get to know how many shims to remove by looking at oily the paper still is when you undo the bearing cap. Lots of oil = wide clearance. Paper squeezed dry, tight. Ideal is evidence of the paper being squeezed but not dry - just a little wet with oil.
Leave the bearing you have just done loose so you have a good "feel" for the next. When all are done, tighten them all to the appropriate tension (35ftlb on the big ends and 45ftlb on the main bearings) and check the shaft for "drag". You should be able to easily turn the shaft with your hands.

do you think that a machinist uses a page from the phone book or
news paper? I doubt it

[H. L. Chauvin]

Hi Mr. Texas,

In talking to many vintage well experienced steam engine mechanics & vintage auto mechanics years ago, I had never heard of using Plastigage, aluminum foil, newspaper, or telephone books when we set Babbitt bearings back then. All of these vintage guys had the same Babbitt bearing setting recommendations as follows:

If the engine is removed, one very quick method if you want to save time is to:

1. First number, mark & separate each of all four connecting rods & pistons 1 through 4 so they are re-installed in the same cylinder.

2. Remove all 4 connecting rods & pistons & insure to replace same numbers of shims on each side of each numbered rod after removal.

3. After piston removal, wipe excess oil film from both connecting rod Babbitt & journals.

4. Assemble one rod at a time to first "feel" for up & down movement. If slight up & down movement is felt, remove shims & tighten until "no" up & down movement is "felt".

5. Make sure after feeling no up & down movement, that connecting rod bearing can easily move from "side to side".

6. Then rotate crank to insure that the journal is round & the connecting rod does not bind when rotated.

7, After years of setting Babbitt like this, I later tried Plastigage about 6 years ago "after" quickly setting all four connecting rod clearances like this only to find that the Plastigage confirmed that I had already achieved the correct clearance.

8. Then I went back to "not" using Plastigage.

9. The mains can be adjusted the same way, one at a time, middle, front, & rear, "no" felt up & down movement, & easy fore & aft movement.

10. After experiencing the "feeling" of movement & doing only one engine, all of the next ones can be done in a jiffy.

11. Ford described this method in his earlier Model T Bulletins but did not repeat this method in his Model A Bulletins -- guess he thought by 1929 all Ford mechanics already knew how to properly set Babbitt bearings.

Just hope this helps anyone setting Babbitt bearings..

[Synchro909]

forever4, So you drive a Model A and don't know what a newspaper or phone book is!?!?! Use a micrometer and find another piece of paper about 2 thou thick.
Brendan, I know a machinist who uses paper but none who use plastigauge.
To both of you, whatever floats your boat is fine by me but I get excellent results with my method and I figure the less sophisticated it is, the less chance of something going wrong - that's part of the magic of our Model A's.

[Mike V. Florida]

Mike Flanagan has posted his description of interference fitting of the main bearings in the Model A engine. Because of the weight of the flywheel and the flexibility of the Model A crank, plastigauge may not be a reliable method of adjusting the bearing clearances.
Here's Mike:
How do you check the clearance on the bearings? It is not QED but can be done if you can lay on your back and work with oil and grit and grime falling in your eyes.
First you gotta drop the pan, let it sit overnight to get all the oil that will fall out to do so. You are still going to get oily. Pull the damn oil pump out and lay it aside. You can shine a flashlight up in there to see which way the tang is oriented to reinstall and with it out there won't be so damn
much blood on it to clean off it.
Then I start with the center main. This one requires that the valve cover be taken off as the nut is in side there. The other nut is between 2 and three outside on the other side. Remove the cap being careful to keep the shims on the same side as they came from. Visually inspect the bearing for cracks and places at both the front and back that look as if it has been compressing the babbitt
and pushing it forward or to the rear. Bad signs if so. To check the clearance, use a piece of aluminum foil .002 thick. The heavy duty she buys to do heavy-duty things is .002 but the regular like you cook a baked potato in is .001 so you fold it. You want a piece as long as the cap and about 1/2 wide. Lay this in the cap and with the SHIMS BACK IN THERE put the cap back on and tighten it up. Now you want to see if the motor will turn with the obstruction in
place. Stick a 6" punch in one of the balance holes in the crank throw so the pull will be consistent each time you check. You are looking for lockup with the obstruction in there and free without. The shims are increments of .002 or .003 depending on which the rebuild used.
The steel shims are generally in .002 and the brass in .003. Peel 1 increment from one side at a time, one from one side and if that doesn't lock it up then do one from the other side. Yes it tedious; just be glad you didn't by a space shuttle. Once you get this bearing to lockup then
remove the obstruction and replace it and tighten it up again and see if it will rotate. If it won't turn with the 6" punch then put that dame shim back in and run it another 3k.
Do the rear next then the front. The rods adjust exactly the same way. When you finally get a bearing adjusted like you want it put some pre-lube (engine assembly lube) on there before putting it on there for the last time. Torque to whatever you has been using (75 minimum) and go. The rod nuts torque to 40.
To put the pan on there install the oil pump using a 3/8 fine thread bolt in the plug hole in the side of the block to retain the pump while you install the pan. Finger tight as the threads are actually national pipe threads but the bolt will work in there. Get some 5/16 all thread and make yourself some cheaters by cutting 4 pieces 4 or 5 inches long. Screw them into the pan rail and
let 'em hang down. Slip the pan over them and start a nut. Then it is a matter of tightening the nuts incrementally in turn and thereby winching the pan up against the spring on the pump.
The gaskets and sealer is a matter of choice but my opinion is that the silicone belongs in the bathroom. I use permatex red personally. When you put it all back together put some of the oil down the dist hole so the valve galley is oiled. It should not have lost any oil but I like to make sure.

[H. L. Chauvin]

Mr. Mike V.

What ever happened to Mr. Flannigan. Last time he sent me private e-mails, he told me his health was failing.

AHOOGA Forum still has lots of his very sincere helpful suggestions. He was a such a very interesting person to converse with about Model A's & he liked the aluminum foil method to adjust bearings; but, always advised to check the foil thickness with a micrometer.

[Kohnke Rebabbitting]

There must be more shade trees in some parts of the world, then others!

If I was going to set rod bearings with paper, I would use a good quality, and the Cadillac of all precision bearing papers with the world renown prestige that any Lincoln Tec. Grad. Mechanic or Superior Machinist worth his salt would use.

That my friends, is the Multi Purpose Sears Catalog of 2014. Yes, any Mechanic will shiver as he runs his Heavily Calloused fingers along the precision bearing paper, acknowledging it's, strength, ease of use, and most of all the, easy tear pages.

The only con from using this type of precision paper is if you use any pages from the Ladys Lacy section, your bearing job can double the time and price, which is not fair to your one time only customer.

But you can also save money, as after a hard days work of bearing setting, and the paper is saved, it would make a remarkable addition to any one's out house.

Yes, Yes, I know, everybody is wondering about the oil stained bearing paper in an out house. Well, I have always said, who needs a mirror on the bottom of a deep hole anyway.

Herm.

[Kohnke Rebabbitting]

I agree Mr. Coupe.

I go for the noticable drag, and put a .001 thousandths shim back in one side.

If the drag is left, the crank pin will push the bearing back.

Herm.

[H. L. Chauvin]

Mr. Herm,

Thanks kindly for your most intelligent vintage remarks from "experience" rather than quoting from so called vehicle Forum experts; but, in my opinion, just with Plastigage, if anybody would ask Grandma if biscuit dough is more pliable with more milk or less milk Grandma would give a common sense engineering answer; hence, after time I have experienced that Plastigage sitting in an NAPA store for years dries out after a few years & if dry, can give false readings when dried out & trying to measure 00.0015".

Pounds per square inch on dry biscuit dough or wet biscuit dough is far above that being taught today for a Master's Degree in Engineering or on a vehicle Forum.

Thanks for your input.

Most men don't realize they already know how to feel for something -- they just don't try it on Model A's like people did years ago.

Just as soon tell it like it is.

[Mike V. Florida]

I've always found it interesting that there are those that have done a thing hundreds or perhaps thousands of times and have that thing down cold. They can do it in their sleep. I don't think they were born with that knowledge, the ability to it diagnose a problem with with just a short listen, feel, or even a smell. They take absolutely no time in rebuilding something as their hands just seem to fly about just knowing where an item was placed, the amount of force needed to be placed and exactly where. No, I don't think they were born with it but sometimes they do seem to forget that there was once a day when they too faced that project for the first time. Looking at that project for the first time and asked, how is this done, where do I get the parts, and what happens if I get it wrong. Their long held, hard earned, understanding most likely came from someone that traveled that same road before them and seeing that it worked well continued it for all those hundreds and maybe thousands of times. Maybe, just maybe, there is another guy that has successfully done that very same job, hundreds and thousands of times successfully, only a different way.

[George Miller]

Originally Posted by Kohnke Rebabbitting

I agree Mr. Coupe.

I go for the noticable drag, and put a .001 thousandths shim back in one side.

If the drag is left, the crank pin will push the bearing back.

Herm.

That is the way I have done it for the last 60 years also.

[BILL WILLIAMSON]

Originally Posted by Kohnke Rebabbitting

There must be more shade trees in some parts of the world, then others!

If I was going to set rod bearings with paper, I would use a good quality, and the Cadillac of all precision bearing papers with the world renown prestige that any Lincoln Tec. Grad. Mechanic or Superior Machinist worth his salt would use.

That my friends, is the Multi Purpose Sears Catalog of 2014. Yes, any Mechanic will shiver as he runs his Heavily Calloused fingers along the precision bearing paper, acknowledging it's, strength, ease of use, and most of all the, easy tear pages.

The only con from using this type of precision paper is if you use any pages from the Ladys Lacy section, your bearing job can double the time and price, which is not fair to your one time only customer.

But you can also save money, as after a hard days work of bearing setting, and the paper is saved, it would make a remarkable addition to any one's out house.

Yes, Yes, I know, everybody is wondering about the oil stained bearing paper in an out house. Well, I have always said, who needs a mirror on the bottom of a deep hole anyway.

Herm.

YOU'RE FUNNY, HERM
You'se guys are LUCKY, I tiped a LOOOOOOONG response to this, & LOST IT!!! (DAMN!)
Bill W.

[Patrick L.]

back in and run it another 3k.
end quote



3K ? I sure don't want to have to do this every 3K miles.

[Kohnke Rebabbitting]

Originally Posted by H. L. Chauvin

Mr. Herm,

Thanks kindly for your most intelligent vintage remarks from "experience" rather than quoting from so called vehicle Forum experts; but, in my opinion, just with Plastigage, if anybody would ask Grandma if biscuit dough is more pliable with more milk or less milk Grandma would give a common sense engineering answer; hence, after time I have experienced that Plastigage sitting in an NAPA store for years dries out after a few years & if dry, can give false readings when dried out & trying to measure 00.0015".

Pounds per square inch on dry biscuit dough or wet biscuit dough is far above that being taught today for a Master's Degree in Engineering or on a vehicle Forum.

Thanks for your input.

Most men don't realize they already know how to feel for something -- they just don't try it on Model A's like people did years ago.

Just as soon tell it like it is.

Mr.H. I use Plastigage several times a week. When it gets old, it does start to get fragile, but it still works 100% if you use it correctly.

Most people try to use it dry, It won't work that way! Any of it!

1. You have to use oil of about two drops on the shaft, and bearing.

2. Never use the cap to read the clearance. Always use the shaft.

Herm.

[Kohnke Rebabbitting]

Pictures.