babbit tolerance? .000?

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Railcarmover said:
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.
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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.
 

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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?
 
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.

Per Ford drawing A-6015 (April 1929), the cylinder bore was specified to be reamed to 3.873 to 3.874 inch diameter, and then rolled to 3.875 to 3.876 inch diameter. There is no mention of boring or honing.
 
Terry Burtz said:
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.

Per Ford drawing A-6015 (April 1929), the cylinder bore was specified to be reamed to 3.873 to 3.874 inch diameter, and then rolled to 3.875 to 3.876 inch diameter. There is no mention of boring or honing.
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Thanks, Terry. Do you have available the official Ford factory method of obtaining correct bearing sizing and clearances? What did they really do?
 
Terry Burtz said:
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.

Per Ford drawing A-6015 (April 1929), the cylinder bore was specified to be reamed to 3.873 to 3.874 inch diameter, and then rolled to 3.875 to 3.876 inch diameter. There is no mention of boring or honing.
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True Terry about the reaming, and maybe I am looking at it in a different manner of terminology (then & now) that boring and reaming can be synonymous in meaning. I guess the way I also look at it is that on the print, it also mentions finish sizes of other bearings or bores but really does not tell you how to get there. I think much of that came from common sense and SOP from the Machine Shop employees who just knew what was necessary, and that knowledge was passed down to the apprentice machinists that came thru the factory. One "other final" thought of mine is while using a reamer will put you to an exact size, it will not produce a surface finish conducive for a cast iron piston ring. Therefore they had to grind (-or hone) to finish size. Am I still missing something??
 
Also Terry, does your print give a minimum spec on Brinell hardness for the bore and a max spec. taken on the pan flange? What do you think is the Engineer's mindset for measuring in two different locations? Why not give a minimum & maximum for both locations??
 
I see evidence of the brinell test on crankshafts, steering arms, front axles, haven't seen it on blocks, rods, main caps, I think it was just done on heat treated parts
 
I think they were more concerned with hardness on rotating assemblies. Brinell testing is mostly used on course stuff like castings but the stationary parts were not all that hard. If cast iron is too hard it gets brittle. Casting techniques then were not what they are now for sure.

Ford used tooling to get the job done as quickly as possible with the best results possible. Honing of cylinders is not something that can be skipped. They may have used ball hones so they could get a quick cross hatch without worrying about set up and stone wear but I don't know for any certainty. Rings won't break in without a proper crosshatch on the cylinder walls. If they were power honed, it would likely have been by a machine that could do all four cylinders at once. Boring would have been done the same way. It can be called reaming if that was how the tooling was designed. Some of the machines Ford had were pretty amazing. They would drill and tap all of the holes on the block at the same time.
 
BRENT in 10-uh-C said:
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.
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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.
 
Let me shed some light on these questions of machining. It was stated cylinder bores were reamed then rolled to finish size. No mention of boring or honing. Both processes mentioned, "reaming" and "rolling" are still commonly used industrial processes that lend themselves to fast, economical work cycles.
It appears that the rough cast bores were reamed ( think of a large core drill) to near finish size , then a roll finisher used to bring to finished size and required surface finish. Apparently Ford did not hone. Honing in a large scale high production operation is a costly and potentially hazardous operation. Hazardous because of the (typically) used kerosene honing fluid. An industrial honing area in an automotive production plant would require partial enclosure and installed flooding ( CO2 ) fire suppression systems. Apparently Ford found a way to avoid all this by roll finishing that cylinder bores.
My $0.02 opinion based on 40 year experience as engine/ axle automotive manufacturing engineer.

Joe B
 
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rotorwrench said:
I think they were more concerned with hardness on rotating assemblies. Brinell testing is mostly used on course stuff like castings but the stationary parts were not all that hard. If cast iron is too hard it gets brittle. Casting techniques then were not what they are now for sure.

Ford used tooling to get the job done as quickly as possible with the best results possible. Honing of cylinders is not something that can be skipped. They may have used ball hones so they could get a quick cross hatch without worrying about set up and stone wear but I don't know for any certainty. Rings won't break in without a proper crosshatch on the cylinder walls. If they were power honed, it would likely have been by a machine that could do all four cylinders at once. Boring would have been done the same way. It can be called reaming if that was how the tooling was designed. Some of the machines Ford had were pretty amazing. They would drill and tap all of the holes on the block at the same time.
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You are right, Mr. Rotor, on the cylinder reaming, all at once. I have seen it in Ford videos !

Herm.
 
After watching this video a few assumptions can be made..Ford did not line bore assemblies,you are correct.Ford held a strict tolerance through out the process negating the need for line boring the assembly.They basically assembled them and 'spun them in' using an electric motor on a stand,spun them till the engines resistance fell into spec. The honing and cylinder process is covered by the video as well.

https://www.youtube.com/watch?v=Xa0PAg7FfMk

KWL2COq.jpg


Here another photo of Ford spinning engines to a prescribed resistance..the shear size of the Rouge operation is fascinating.
 
A very interesting and informative video for sure. Thanks for posting.
As for the cylinder bore machining process, the short sequence shows no honing operation. In deed, there is a view of an cylinder bore reaming operation and what surly appears to be a roller (burnishing) finishing operation on the bores. So it looks like Ford was still using this process on the V8's

Joe B
 
Brent,

There are no Brinell hardness requirements on the drawings.

I agree that most dimensions are specified without telling the machinist how to do it. Some dimensions tell the machinist to "Grind" like the crankshaft journals, or to "Ream" and "Roll" like the cylinder bores. We now know that the cylinders should not be rolled, but instead honed like this: https://www.hastingsmfg.com/ServiceT...efinishing.htm

Compared to a modern engine, the tolerances in a Ford Model A engine are very loose and I believe that they needed to be "broken-in" by spinning with an electric motor until the amperes (torque) dropped to a certain level.

The crankshaft connecting rod journals on drawing A-6303 are specified to be ground to 1.497 to 1.499 inch diameter (each of the rod journals could be different), and they could be ground undersize per drawing note on A-6303 which reads "see specification MS 46303 for salvaging crankshaft".

The connecting rod drawing A-6200 specifies 2 different big end diameters. A-6200-A has a big end diameter of 1.4965 to 1.4970 inches, and A-6200-B has a big end diameter that is 1.4865 to 1.4870 inches (which is .010 inches undersize).

If you were to see the big picture, every engine could have connecting rods with 4 different diameters and main bearings with 3 different diameters.

The engine assembly drawings that I have call for a pair of shims at all connecting rod and main bearings.

Regarding engine "break-in", I agree 100% with Vince Falter where he explains it here: http://www.fordgarage.com/pages/bearingshims.htm

Once broken-in, the engine was stamped with the serial number.
 
Railcarmover said:
Mr Kohnke,perhaps you can shed some light on why Ford never showed their babbitting process?
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I haven't looked at many V-8 videos, to see any pourings exist, but I have seen the T, and A ones. They were poured babbitt from 1932, to early 1936.

If you want accuracy on measuring all bearings to a 1/10 of a thousandths, every time, use an inside Mic. and an out side Mic to measure that. "Pictures"

As far as the two videos go, every thing is wrong.

Does this look like what you have seen. These mains and rods are ready to bolt together. "Pictures"

Like Jim said, set clearance at .002, when broke in it will be about .003 to .003-25, or -50. Never under .001-60, or you will loose unnecessary bearing surface Babbitt.

NO shim removal, no time saver, no burning in to ruin the first .010, of babbitt. If you have to pull a motor in a car to turn it over, where the starter , and hand crank won't, find a different engine builder.

The engine assembler got fed all useless, Information. I felt sorry for him, as he looks pretty sharp, and a nice clean shop.

When I seen the Babbitting job in progress, I knew what all the rest was going to be like.

My Opinion,

Herm
 

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Kurt in NJ said:
I see evidence of the brinell test on crankshafts, steering arms, front axles, haven't seen it on blocks, rods, main caps, I think it was just done on heat treated parts
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rotorwrench said:
I think they were more concerned with hardness on rotating assemblies. Brinell testing is mostly used on course stuff like castings but the stationary parts were not all that hard. If cast iron is too hard it gets brittle. Casting techniques then were not what they are now for sure.
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Well, if y'all say so..


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it makes sense from Hagerty's perspective..bangers are the future of model a collecting..he doesn't mention the rule of 9's when adjusting the valves either..
 
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