Checking bottom end bearing clearances

Licensed to kill

Licensed to kill

Well-known member
So while I have the pan off I wanted to check my bearing clearances. Did alot of searching and due to necessity (can't find any plastigauge locally) decided to do the go-nogo method. Kind of a hokey way to do things but most things about these cars is kinda hokey and they are not exactly precision pieces of equipment. Started with the rear main since i already had that one off to fix the missing oil tube issue. With 4 shims removed, the crank turns freely and drags with a piece of .002 tin foil in but does not lock up. remove one more .002 shim and the crank drags with no tin foil. Seems too snug to me and to my way of thinking if it drags with .002 foil in there, then the actual clearance would be something like .0015 would it not??. Drag suggest to me that there is virtually no clearance. I'm thinking go with the 4 shims removed rather than the 5. Am somewhat surprised that I had at least .004 too much clearance (2-.002 shims from each side.
 
Sounds like you're on the right track with your shim method. With just a little practice this is more accurate than Plasti-Gage but more time consuming.
Something to watch for with Plasti-gage: On the rods, if the cap doesn't come off easily, do not tap on the rod bolts! That will flatten the Plasti-gage strip more and give a false reading. When doing the mains with Plasti-gage, put a jack under the crank and put just enough force on it to support the crank so the weight of the crank doesn't flatten the Plasti-gage excessively and give a false reading.
 
Every auto parts store I have ever dealt with carries it.
Where the heck do you live?
 
Every auto parts store I have ever dealt with carries it.
Where the heck do you live?
 
Tiny said:
Every auto parts store I have ever dealt with carries it.
Where the heck do you live?
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Yup, back when I had my '57 (in the 70's-80's) that was also the case. never gave it much thought as I figured I could get it anywhere. Called the local NAPA and he said he has been trying but can't find a supplier. ????WTF, people still build engines don'y they?? Blew my mind. I will track some down. I know where I can get some but it's about an hours drive one way. Seems a long way to go for $5 worth of plastigauge but..........:(
 
I get my Plastigage from Snyders, even with the shipping cost. They have fresh stuff in a plastic bag. Local Napa has the stuff, but it is dry, brittle and give odd readings. I keep the leftovers in a plastic bag too.
 
I finished up with the mains today using the go-nogo method. Took about n.002 out of the front and centre and .004 out of the rear. I could hear a faint knock at idle before and it sounded like it was coming from the rear of the engine. Don't know if the .004 extra clearance was the cause. I guess we will see. All the while doing the front main I kept quoting Jerry Reed "Lord Mr Ford what have you done?". Seriously, he couldn't have used studs. I know he was familiar with the concept because he used them in the rear. what a PITA. Honestly don't know how i would have done the front main without a lift (or a helper I guess).I'm going to use plastigauge for the throws.
 
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Licensed to kill said:
I finished up with the mains today using the go-nogo method. Took about n.002 out of the front and centre and .004 out of the rear. I could hear a faint knock at idle before and it sounded like it was coming from the rear of the engine. Don't know if the .004 extra clearance was the cause. I guess we will see. All the while doing the front main I kept quoting Jerry Reed "Lord Mr Ford what have you done?". Seriously, he couldn't have used studs. I know he was familiar with the concept because he used them in the rear. what a PITA. Honestly don't know how i would have done the front main without a lift (or a helper I guess).I'm going to use plastigauge for the throws.
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And some say, "OH, while you got the pan off, check the clearance on the MAINS"---As if it's a 20 Minute Picnic:D--IT'S A ***** OF A JOB--NLOL:eek::eek:
Bill Oily
 
Hi LTK,

There is a very typical method described in the Model T manuals for adjusting Babbitt bearings by a method which was used going back to adjusting Babbitt on the 1850 steam engines.

Plasti-gage was not introduced until long after Model T's and A's and it was first introduced in 1948. I personally never knew of anyone who used Plasti-gage for Babbitt bearing adjustment in our area. I'm sure that in 1948 when it was introduced, vintage mechanics had no time to fool around playing with this plastic stuff.

I adjusted my 1930 Coupe bearings in about 1960, (57) years ago .... engine ran 36 years with no problems .... still have same engine to re-install in Coupe; and ten (10) years ago I adjusted my Model A mains and connecting rod bearings the same vintage way without Plasti-gage, without metal shim material, without aluminum foil and have had absolutely no problems.

In fact, I never heard about Plasti-gage or using aluminum foil or metal shims until reading same on Model A Forums where it appears it has become some form of religious activity where Plasti-gage has to be as fresh and as soft as fresh chicken poop.

In 1958 I was taught how to adjust Model A Babbitt bearings by my mechanic father, (born 1902), and his mechanic brother born 1905; both who learned from their engineer father, (born 1867), & who adjusted steam engines and gasoline engines. He was taught by his father, steam engine mechanic, (born 1836), who was taught by his father, steam engine mechanic (born 1813), working on his brother's two (2) Paddle Wheel Steamers, the Paragon and the Teche. We still live in this same area.

We always first removed Model A engines and inverted them so this work could be done in a jiffy. But just like pouring Babbitt, it is an "art" & a science .... if one is lacking dexterity and is lacking the "art" part ..... best advice is to go buy a pack of the Plasti-gage which can pass the fresh chicken poop test.
 
BILL WILLIAMSON said:
And some say, "OH, while you got the pan off, check the clearance on the MAINS"---As if it's a 20 Minute Picnic:D--IT'S A ***** OF A JOB--NLOL:eek::eek:
Bill Oily
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Yep, it is a job. How about using a dial indicator and move the crank up and down to measure the clearance? The bad thing is you won't get to see the condition of the babbit.
 
Tom Wesenberg said:
Yep, it is a job. How about using a dial indicator and move the crank up and down to measure the clearance? The bad thing is you won't get to see the condition of the babbit.
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I don't know that you would be able to manually get the crank to move well enough to get an accurate reading. It's only a PITA trying to do it alone. Wouldn't be so bad with a helper. Be tempting to put the bolts for the front main in from the top and weld them in place turning them into studs. As if it's not bad enough to use bolts that go up from the bottom and come out on the outside of the block, then they decide to use a square head on the bolts also. WTF is up with that??.
 
Licensed to kill said:
I don't know that you would be able to manually get the crank to move well enough to get an accurate reading. It's only a PITA trying to do it alone. Wouldn't be so bad with a helper. Be tempting to put the bolts for the front main in from the top and weld them in place turning them into studs. As if it's not bad enough to use bolts that go up from the bottom and come out on the outside of the block, then they decide to use a square head on the bolts also. WTF is up with that??.[/QUOTE]

They want you to take it back to the Ford dealer. :D
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Seriously, he couldn't have used studs. I know he was familiar with the concept because he used them in the rear.
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The rear main doesn't have studs, it uses bolts w/a special head to prevent them from turning.

The square head main bearing bolts have a dimple on then. showing the alignment of the cotter pin hole.
 
Someone compared Plasti-Gage to SOFT CHICKEN POOP, you know what that WHITE stuff in Chicken Poop is????---It's Chicken Poop, TOO!!!
Bill Inquisitive
 
Mr. LTK,

This art of adjusting Babbitt bearings is not any different from trying to find a single craftsmen in 2017 who can successfully build a boat by cutting wood planks with a hand saw & shaping rough wood planks with a carpenter's hand plane; yet, why was it successfully done so often in Model T days?

If after adjusting the shims, if the crankshaft cannot move easily sideways, Babbitt adjustment is too tight.

All vintage mechanics I knew in our area could feel individual, adjustable up & down journal movement and rotational tightness after wiping off and removing the film of oil on the journals and Babbitt.

If an individual could not successfully perform this task after hands on training years ago, (and there were some), they were never trusted to try to allow them to continue try to do this type of work.

After 20 years of reading Model A Forum restoration messages about all of the Model A engine knocking & Babbitt failures right after engine rebuild, there is a definite learning gap where this art of Babbitt adjustment and craftsmanship was never handed down through generations.
 
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