babbit tolerance? .000?

[mike657894]

haggerty is rebuilding a model A engine. He says you start with 0 clearance then bed it in. Is he correct or should there be.0005 or .001 or.0015? link to youtube video. haggerty rebuilding model a engine. https://youtu.be/anDIASMNmCQ?t=39

[BRENT in 10-uh-C]

Originally Posted by mike657894

haggerty is rebuilding a model A engine. He says you start with 0 clearance then bed it in. Is he correct or should there be.0005 or .001 or.0015? link to youtube video. haggerty rebuilding model a engine. https://youtu.be/anDIASMNmCQ?t=39


<iframe width="560" height="315" src="https://www.youtube.com/embed/anDIASMNmCQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

While he admits he doesn't know anything about babbitt, we all need to remember that just because something is posted on YouTube or the internet does NOT make it correct. In this case, he is basically incorrect.

[Patrick L.]

I've scraped large babbit bearings. You just keep marking and scraping to 'bed' them.

But I don't do that to adjust a small bearing such as ours. I like ours to end up at .0015"

[Dick So. Cal.]

How do you measure 0 clearance?

Dick

[mike657894]

Originally Posted by Dick So. Cal.

How do you measure 0 clearance?

Dick

not with platigauge. but if you wanted to you would mic the crank and use a bore set to measure the main and match them up


I dont have a bore set just a set of those expanders and I dont trust those as far as I can throw them

[Jim Brierley]

Sponsored Links (Register now to hide all advertisements)

I believe that when babbitt is machined, there is no need to 'bed' it in. I like .0015, more if you are going to race it. I set my Bonneville engine at a minimum of .002".

[Railcarmover]

You should watch the video of them pouring that babbit..yikes...Ford spun engines in with an electric motor, they used an ammeter to determine the resistance value. Burnishing the mains,allowing the last step of fitting the bearings to the crankshaft itself through rotation.

[Patrick L.]

Originally Posted by Railcarmover

You should watch the video of them pouring that babbit..yikes...Ford spun engines in with an electric motor, they used an ammeter to determine the resistance value. Burnishing the mains,allowing the last step of fitting the bearings to the crankshaft itself through rotation.

I've read and watched old video of that. Makes you shake your head.

[Railcarmover]

Originally Posted by Patrick L.

I've read and watched old video of that. Makes you shake your head.

Cant fit and finish when your building 7500 engines a day..foreman watching you all the time,the stopwatch running..get it close and ship it.if it failed to spin down to the value it went back to the motor building if it could be fixed quick it was,if not it was scrapped.

Ford's assembly line was a cold unforgiving environment..if it works and was installed in time great,if not? scrap it...or fire him..

[rotorwrench]

There has to be clearance to allow for rotation, lubrication, and to prevent galling of the bearing with heat expansion. Folks that do babbitt work prefer to have a crankshaft in hand to fit the bearings to it. They should be set up with standard shims to allow for future service. There are several tools that can be used to check a bore. A T-gauge will work if you know how to use one but a ball gauge can work better. Snap gauges work well too. An inside mike has to be small enough to fit the bore size but they will also work well.

I would talk to someone who does this stuff for a living and find out how they do it successfully. "Bedding In" can mean different things to different people.

[Patrick L.]

https://www.youtube.com/watch?v=anDIASMNmCQ


Hagerty

[rotorwrench]

Assembly lines are all hard work jobs no matter what the company or the product. Since Ford developed the assembly lines, they were good at making improvements to keep up both production and quality. If a line inspector was letting too many failing products by, they would have come looking for him so it was not just the line that had to worry about stuff. This type of work would have been better for the younger folks since it's not a sit down job but they paid their workers pretty well.

Some of the first person accounts mention that Ford kept their buildings cleaner than most of the other auto manufacturers did. One thing I felt about the assembly line work, since I worked on one while I was in A&P school, is that the time went by fast and then you were out of there. You just get damn good at putting widgets in the thingamajigs. I helped put glass in a lot of boat windows while I did that type of work. The glass all came from a Ford Motor Company glass plant.

[BRENT in 10-uh-C]

Originally Posted by Railcarmover

Cant fit and finish when your building 7500 engines a day..foreman watching you all the time,the stopwatch running..get it close and ship it.if it failed to spin down to the value it went back to the motor building if it could be fixed quick it was,if not it was scrapped.

Ford's assembly line was a cold unforgiving environment..if it works and was installed in time great,if not? scrap it...or fire him..

Originally Posted by rotorwrench

Assembly lines are all hard work jobs no matter what the company or the product. Since Ford developed the assembly lines, they were good at making improvements to keep up both production and quality. If a line inspector was letting too many failing products by, they would have come looking for him so it was not just the line that had to worry about stuff. This type of work would have been better for the younger folks since it's not a sit down job but they paid their workers pretty well.

Some of the first person accounts mention that Ford kept their buildings cleaner than most of the other auto manufacturers did. One thing I felt about the assembly line work, since I worked on one while I was in A&P school, is that the time went by fast and then you were out of there. You just get damn good at putting widgets in the thingamajigs. I helped put glass in a lot of boat windows while I did that type of work. The glass all came from a Ford Motor Company glass plant.

I fail to see what you guys are calling 'time to ft and finish'. All the components were designed to fit. All crankshaft & rods were poured with identical mandrels, and all crankshafts were machined to the same specs. The Assembler did not need to check clearances of bearing or bores, nor monkey with valve lash clearances as EVERYTHING was the same from engine to engine.

[Railcarmover]

That's my point,time wasn't spent with the knife If a crank didn't spin easy,it was assembled and burnished by spinning on the 'break in stand'.They didn't use shim packs much either,as you say there was one spec, and machines were calibrated regularly.

[BRENT in 10-uh-C]

Originally Posted by Railcarmover

That's my point,time wasn't spent with the knife If a crank didn't spin easy,it was assembled and burnished by spinning on the 'break in stand'.They didn't use shim packs much either,as you say there was one spec, and machines were calibrated regularly.

You mentioned burnished on a break in stand. Do you have evidence of a break-in stand? If you are calling what I have pictured below as a break-in stand, I don't believe that is what this unit was.


Burnishing is accomplished by multiple heat cycles of spinning the crankshaft until the babbitt becomes slightly 'fluid-like' or 'plastic' then allowed to cool. The unit pictured below never spun for long due to there not any engine oil or trans lube in the assembly.


Your comment about them not using shim packs much kinda needs some clarification. First, the shims were specified to be 0.002 - 0.0025 in thickness. Ford did not line-bore the blocks and caps together. The babbitt in the blocks was specified to be bored to 1.623" - 1.624". The caps were specified to be bored to 1.618" - 1.620". The crankshaft main journals were to be ground to 1.622" - 1.624". When the three components were assembled, it effectively had 0.000" tolerances when you do the math, so 'one can assume there was indeed 0.000" clearance requiring burnishing however I have never seen pictures that show this process. To clarify my statement about what Damon said in the video, it is true that at one point in the original machining process where the babbitt did have 0.000" clearance however it did not leave the factory with that clearance. That would be like saying the engine cylinder cases (blocks) were bored to 3.8735" in size. While that is accurate statement, that was not the finished bore size after honing.

[mike657894]

interesting. So assembled with .001-.002 tight on the block mains and .005 tight on the main caps and 3-4 or so shims to give a .001-.002 tolerance on crank from factory?

[Railcarmover]

Originally Posted by BRENT in 10-uh-C

You mentioned burnished on a break in stand. Do you have evidence of a break-in stand? If you are calling what I have pictured below as a break-in stand, I don't believe that is what this unit was.


Burnishing is accomplished by multiple heat cycles of spinning the crankshaft until the babbitt becomes slightly 'fluid-like' or 'plastic' then allowed to cool. The unit pictured below never spun for long due to there not any engine oil or trans lube in the assembly.


Your comment about them not using shim packs much kinda needs some clarification. First, the shims were specified to be 0.002 - 0.0025 in thickness. Ford did not line-bore the blocks and caps together. The babbitt in the blocks was specified to be bored to 1.623" - 1.624". The caps were specified to be bored to 1.618" - 1.620". The crankshaft main journals were to be ground to 1.622" - 1.624". When the three components were assembled, it effectively had 0.000" tolerances when you do the math, so 'one can assume there was indeed 0.000" clearance requiring burnishing however I have never seen pictures that show this process. To clarify my statement about what Damon said in the video, it is true that at one point in the original machining process where the babbitt did have 0.000" clearance however it did not leave the factory with that clearance. That would be like saying the engine cylinder cases (blocks) were bored to 3.8735" in size. While that is accurate statement, that was not the finished bore size after honing.

it appears those model T engines were set in a stand and spun by an electric motor,that large meter behind them I'm sure read amperage,the load on the motor told them if it was spinning at their prescribed load for acceptable resistance of an assembly,in essence a 'break in' stand,in fact Ford did not fire the engines till the car was completed at assembly,so that stand was all the break in the engine got.The same technique was used with the model a engine. I don't know if Ford line bored or not,it would stand to reason that they did,its the only true way to set the main bearings in alignment,just cutting bores on caps to a .005 difference than the bore on the block makes no sense.
Burnishing is the act of polishing metal with metal,ie spinning a crankshaft in a babbit bearing can help set the bearing through polishing..a process that does work with minimal lubrication,which would slow the desired effect.would be interesting to know how ford approached that.

[Purdy Swoft]

I set the clearance at two thousands on the rod and main bearings . I use 20W50 motor oil and have had good results .

[Railcarmover]

Originally Posted by Purdy Swoft

I set the clearance at two thousands on the rod and main bearings . I use 20W50 motor oil and have had good results .

That's my take on things as well,modern oils have better load and shear characteristics through additives today then they had back then making a strict .0015 not a critical as before. I use a diesel grade CK-4 15/40 for load/shear/soot and debris entrainment properties,well beyond what was available in '28.

[mike657894]

In a earlier video he took a tour of rons machine in shandon ohio where they had thier motor rebabited. I looked at there prices pretty reasonable. 240 to have mains poured and cut. I would think he got his info from rons. now there may be a difference between 0 tolerance versus there is no tolerance you need to measure before assembling this engine. if it sticks pull it around the lot till it frees up.



I had stupidly broken a rear main. I got a used one with plan to have the mains rebabited. the used one happened to be worn but for a 10 under crank. So i spent 6-8 hours marking and knifing it. I set to .0015 to match my other mains. Could I have stopped at less as long as it would move? in my cutting it didn't set flat on the block for the first half of the day then it wouldn't move for the longest time.


On shim packs. They were not on every car from the factory but are an aftermarket item? In the catalogs ive seen it stated that the shims are .002 or .003 per leaf? or are the combined shims =.003? how worn would you wait to remove one if they are .003 per leaf? .005? my car has no shims.