Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 6:32 pm
How did the old-timers set bearing tolerances before aids like Plastigage?
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Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 6:32 pm
Piece of newsprint.
Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 6:45 pm
By turning the engine with the hand crank and feeling the resistance.
Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 7:53 pm
Before there was measuring clearances... there was drag starting! 
Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 9:55 pm
1. remove all spark plugs, loosen all bearings except the one you are working on if fitting all bearings. No need to loosen all bearings if other bearings are OK and only working on one bearing
2. then remove shims on bearing you are fitting till it is hard to turn with hand crank. this requires you to remove shim/test/remove shim/ test ect.
3. then apply very light coat of Prussian blue to inside of bearing. tighten the cap and turn over a couple revolutions.
4. remove cap and inspect bearing. any high spots will be shiny.
5. scrape high spots with bearing scraper, re coat with Prussian blue, replace cap and repeat shiny spot checks till a 75% (or better) shiny spot is achieved.
6. replace cap and remove shims again till hand crank is hard to turn,
7. replace one .002 shim, being sure shim packs are equal or only .002 different on one side of bearing. (You should have been keeping the shim packs equal while doing the fitting)
8. by replacing the .002 shim after the bearing is hard to turn with the hand crank, you will end up with aprox .001 clearance (within a half a thou)
9. after fitting and oiled good, you should be able to slide the rod bearings side to side with your fingers.
This is the way I was taught to do it by my grandpa. It is very time consuming to hand fit bearings and takes skill, to do it right. Others may do it different,
2. then remove shims on bearing you are fitting till it is hard to turn with hand crank. this requires you to remove shim/test/remove shim/ test ect.
3. then apply very light coat of Prussian blue to inside of bearing. tighten the cap and turn over a couple revolutions.
4. remove cap and inspect bearing. any high spots will be shiny.
5. scrape high spots with bearing scraper, re coat with Prussian blue, replace cap and repeat shiny spot checks till a 75% (or better) shiny spot is achieved.
6. replace cap and remove shims again till hand crank is hard to turn,
7. replace one .002 shim, being sure shim packs are equal or only .002 different on one side of bearing. (You should have been keeping the shim packs equal while doing the fitting)
8. by replacing the .002 shim after the bearing is hard to turn with the hand crank, you will end up with aprox .001 clearance (within a half a thou)
9. after fitting and oiled good, you should be able to slide the rod bearings side to side with your fingers.
This is the way I was taught to do it by my grandpa. It is very time consuming to hand fit bearings and takes skill, to do it right. Others may do it different,
Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 10:19 pm
Before attempting to set the clearance, I recommend measuring the condition crankshaft journal. If doing serious touring, the out of roundness should be .002 inch or less. For going around the block maybe .004 inch, but. You might have a rod talking to you.
Others might have have other thoughts.
Art Mirtes
Others might have have other thoughts.
Art Mirtes
Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 11:04 pm
Philip. your question does present a few variables in the way of setting tolerances, a fresh repour? or tightening old bearings, has the engine had a rebuild that it has rod shims? from new they did not, cap filing, scraping, Ford preference was burnishing after a nip up of old bearings. I've heard of some who tighten all up and tow the T around for half an hour with the spark plugs out which is a way of burnishing.
Re: Tolerances Before Plastigage
Posted: Wed Dec 01, 2021 11:59 pm
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 2:23 am
My Dad told me that the oldtimers method was to hand fit the bearings in the same manner as Dobro1956 posted above, only after scraping, you would remove shims and tighten the individual bearing until you couldn’t crank the motor. Then go back and add one shim.
I think I prefer having Plastigage.
I think I prefer having Plastigage.
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 7:56 am
An 'old-timer' told me to use a piece of brown paper bag soaked in oil. With the spark plugs out, place the piece of paper bag between the crank journal and the rod cap, If you cannot turn the crank, you are too tight. If you can turn the crank with some resistance, your just about right.
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 8:17 am
Yep, oiled newsprint for checking clearance when removing shims. Shade tree mechanics Plastigage 
Use a fresh piece of print for each cap. With paper between crank and cap, if too tight to turn over, you know the clearance is ok when the paper is removed.
Use a fresh piece of print for each cap. With paper between crank and cap, if too tight to turn over, you know the clearance is ok when the paper is removed.
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 8:29 am
Ford Service Manual: Par 386 tells the Ford approved way to do it.
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 8:34 am
Isn’t it amazing how the ‘old time ‘shade tree mechanics really did know what they were doing!
The term over thinking that’s been around for a while really comes into play when your your around the younger and more tech savvy folks . Or supposed to be more savvy!
The term over thinking that’s been around for a while really comes into play when your your around the younger and more tech savvy folks . Or supposed to be more savvy!
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 12:16 pm
My father was a ford dealership mechanic in 1925. After some experience, he said he just tightened rod bearings with to the point that they felt right. He seldom scraped on an old engine, but did on repours. I still have his old scraping tools.
Art Mirtes
Art Mirtes
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 12:30 pm
The bearing end of the rod should slide back and forth on the journal with slight resistance. If this differs at different positions then the journal is out of round. This has been mentioned by old timers and works for me. I believe this happens between .0015 and .002 on a well fitting rod.
I hadn't bought plastigage for years and what I had dried and shrunk to a thin brittle hair. When I asked for it at the local parts store a month or two ago the young fellow had to ask someone in the back. He eventually came back with some but wouldn't sell it by the strip like they used to.
I hadn't bought plastigage for years and what I had dried and shrunk to a thin brittle hair. When I asked for it at the local parts store a month or two ago the young fellow had to ask someone in the back. He eventually came back with some but wouldn't sell it by the strip like they used to.
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 7:32 pm
Thanks for the tips. I cheated: This is actually for 2 driveshaft babbitt bearings on a 1909 Buick. I must set the clearances while on my back under the car.
Re: Tolerances Before Plastigage
Posted: Thu Dec 02, 2021 8:11 pm
That was clever, but I think that you'd have gotten more specific and useful advice if you hadn't been.
Re: Tolerances Before Plastigage
Posted: Fri Dec 03, 2021 8:22 am
Not so sure you want that tight a clearance on a drive line. (.002")?
T rear end end up closer to .005" (axle /diff clearance is exactly that)
T rear end end up closer to .005" (axle /diff clearance is exactly that)
Re: Tolerances Before Plastigage
Posted: Fri Dec 03, 2021 8:53 am
That is my exact method. Thanks for saving me the typing! (I might add a Timesaver step as well.)dobro1956 wrote: ↑Wed Dec 01, 2021 9:55 pm1. remove all spark plugs, loosen all bearings except the one you are working on if fitting all bearings. No need to loosen all bearings if other bearings are OK and only working on one bearing
2. then remove shims on bearing you are fitting till it is hard to turn with hand crank. this requires you to remove shim/test/remove shim/ test ect.
3. then apply very light coat of Prussian blue to inside of bearing. tighten the cap and turn over a couple revolutions.
4. remove cap and inspect bearing. any high spots will be shiny.
5. scrape high spots with bearing scraper, re coat with Prussian blue, replace cap and repeat shiny spot checks till a 75% (or better) shiny spot is achieved.
6. replace cap and remove shims again till hand crank is hard to turn,
7. replace one .002 shim, being sure shim packs are equal or only .002 different on one side of bearing. (You should have been keeping the shim packs equal while doing the fitting)
8. by replacing the .002 shim after the bearing is hard to turn with the hand crank, you will end up with aprox .001 clearance (within a half a thou)
9. after fitting and oiled good, you should be able to slide the rod bearings side to side with your fingers.
This is the way I was taught to do it by my grandpa. It is very time consuming to hand fit bearings and takes skill, to do it right. Others may do it different,
I really don't like plastigage to be honest. It really doesn't give an accurate picture of bearing contact.
Re: Tolerances Before Plastigage
Posted: Fri Dec 03, 2021 11:05 am
The first 3 are pretty easy. The 4th on a 3 dip crankcase is much harder. You need to turn to one side to work on one nut and about 1/4 turn the opposite way to work on the other nut. Be sure to put a rag behind the bearing to keep from dropping anything in the sump and remember to remove the rag before rotating the crankshaft. It is a pain if you need to keep removing the cap to make adjustments.
Norm
Norm
Re: Tolerances Before Plastigage
Posted: Fri Dec 03, 2021 8:17 pm
Jerry, I did not add the timesaver step as the original question was about how the old timers did it. I do use time-saver as my final step of fitting just before step 7 .
One more trick I use when using time-saver is to wash out the bearing with carburetor cleaner during cleanup. I have cleaned the bearings very well with rags and washing in gas .. But when I oiled the bearing and put it back in place and cranked it over a few revolutions, the oil always looked black and dirty when I removed the cap again. No matter how much I cleaned the bearing the oil always looked dirty when I checked it after turning it over. But when I use carburetor cleaner to do cleanup, the oil still looks fresh and new when I re-inspect it. I know they say time-saver does not inbed into the bearing, But something is turning the oil black ???? So I use carb cleaner to do the final cleanup. Just my 2 cents worth of wisdom for the day .....
Have fun and be safe ........
One more trick I use when using time-saver is to wash out the bearing with carburetor cleaner during cleanup. I have cleaned the bearings very well with rags and washing in gas .. But when I oiled the bearing and put it back in place and cranked it over a few revolutions, the oil always looked black and dirty when I removed the cap again. No matter how much I cleaned the bearing the oil always looked dirty when I checked it after turning it over. But when I use carburetor cleaner to do cleanup, the oil still looks fresh and new when I re-inspect it. I know they say time-saver does not inbed into the bearing, But something is turning the oil black ???? So I use carb cleaner to do the final cleanup. Just my 2 cents worth of wisdom for the day .....
Have fun and be safe ........
Re: Tolerances Before Plastigage
Posted: Sat Dec 04, 2021 7:20 pm
Good information Donnie!!dobro1956 wrote: ↑Fri Dec 03, 2021 8:17 pmJerry, I did not add the timesaver step as the original question was about how the old timers did it. I do use time-saver as my final step of fitting just before step 7 .
One more trick I use when using time-saver is to wash out the bearing with carburetor cleaner during cleanup. I have cleaned the bearings very well with rags and washing in gas .. But when I oiled the bearing and put it back in place and cranked it over a few revolutions, the oil always looked black and dirty when I removed the cap again. No matter how much I cleaned the bearing the oil always looked dirty when I checked it after turning it over. But when I use carburetor cleaner to do cleanup, the oil still looks fresh and new when I re-inspect it. I know they say time-saver does not inbed into the bearing, But something is turning the oil black ???? So I use carb cleaner to do the final cleanup. Just my 2 cents worth of wisdom for the day .....
Have fun and be safe ........