Oil grooves

hazelhoff said:
Now I am the one really getting nervous.
What about the uppers parts of the crankshaft bearings ? Did they have grooves ? Or is that a myth too ?
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What myth? I posted a copy of both the cap and the block from the original Ford blueprints. It clearly shows that Ford engineers specified there are oil grooves.
 
Gentlemen,

Thank you for all the help ! Much appreciate it !
I now know how the grooves should run and their size, thanks to Brent. I would like to talk about oil grooves a little more, but my writing is interrupted all the time ‘cause this website makes me log in when I am ready to send and I then loose my writing. Annoying !
 
Now what I would like to add is some theory of flow mechanics. Everybody knows the phenonemum of aqua planing I guess. A function of car weight, speed, tire size, water film thickness and GROOVES. You would want to install slicks if you had a desire to end up in the ditch.
This is what happens in your babbitt bearings !
 
Oil pressure builds up in your bearing. To accommodate this, the babbitt is not finished very smooth ! It has a certain RMS roughness. The oil film will be a function of crank revolutions, roughness of the babbitt, bearing clearance and leakage ... (leakage is what grooved tires do !).
 
What grooves do is promote leakage ! Grooves in the lower part, the bearing cap, will create leakage in pushing the oil up the way it came from. Up to the wells and from there, up to the oil entry point.
I do not know what Ford engineers were thinking switching from the ungrooved Model T to the Model A, but it doesn’t make any sense to me.
I would never cut grooves in the lower part of the bearing, the place where you want pressure to build up !
Maybe, for the sake of oil supply, I can imagine people wanting to cut an annular half a circle running from the oil entry point to the wells, but that’s it !
On the other hand Ford prescribed sufficient radial clearance for the oil to freely flow to the wells from the entry point. Not cutting grooves seems like a serious option ...

Henk
The Netherlands
 
Brent,

I hope I haven’t offended you ! Myth to me means the thinking within Ford engineering late 20-ies. NOT your valuable documentation !

Henk
 
Henk, To answer your question the block half of the bearings use a short longitudinal groove from the oil hole. This distributes oil across the face of the bearing. This works well, it just may be different than what others do. The oil creates an oil film and oil pressure from the molecules rolling over each other. Rick.
 
DO not compromise the oil system by NOT having the grooves to spec. Believe me not having oil grooves as designed will cause issues with wear and premature failure. Oil's function is to remove heat and separate the parts. This is irrespective of the oil system being pressurized, splash lube , gravity system, etc. If the engine rebuilder forgot the grooves he is obliged to make it correct -or- explain why the engine will run without the grooves. Much money was spent on the re-build I am sure.
 
Richard Knight said:
Henk, To answer your question the block half of the bearings use a short longitudinal groove from the oil hole. This distributes oil across the face of the bearing. This works well, it just may be different than what others do. The oil creates an oil film and oil pressure from the molecules rolling over each other. Rick.
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Rick, I don’t remember where, but I am sure I have seen it pictured somewhere ! It was an oval longitudal shape taking up about half of the length of the bearing ...
Thx again.

Hdnk
 
wwirz said:
DO not compromise the oil system by NOT having the grooves to spec. Believe me not having oil grooves as designed will cause issues with wear and premature failure. Oil's function is to remove heat and separate the parts. This is irrespective of the oil system being pressurized, splash lube , gravity system, etc. If the engine rebuilder forgot the grooves he is obliged to make it correct -or- explain why the engine will run without the grooves. Much money was spent on the re-build I am sure.
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To answer the last part of your comment. The rebuilder was a DAF diesel rebuilder. DAF is a European Truck manufacturer owned by PACCAR (Kenworth etc.) these days. 30 years ago it was all inserts, no babbitt. This (then) young man took it as a saturday morning job. So it was cheap, but not very knowlegable.
 
Rick,

The rebuilder also out felt in the groove holding the oilslinger. How do I get that out of the upper part of the bearing end with the crakshaft still in place ? Any ideas ?

Henk
 
Additional info added since original posting:

hazelhoff said:
Rick,

The rebuilder also out felt in the groove holding the oil slinger. How do I get that out of the upper part of the bearing end with the crankshaft still in place ? Any ideas ?

Henk
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Henk,

I would try this old time idea normally used for installing rope seals.

1. I think that it should work to remove old FELT seal also by lowering crank and pushing out old felt then grab felt with puller...

NOTE: Try pushing the seal BEFORE lowering crankshaft.

With some luck the felt will not be glued into groove.

2. Or try screwing "cork Screw wire" into the felt and then pull out the felt seal.


https://www.napaonline.com/en/p/BK_...IyYbM2NLu7wIVheHACh1rHgmHEAQYHCABEgJIffD_BwE&
 
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Journal bearings work on the hydrodynamic principle, a fixed constant at .001 oil clearance per inch of shaft diameter...10 inch shaft? 10 thousandths clearance. With the hydrodynamic principal applied the journal basically floats on oil.As you can see by the illustration a certain amount of pressure is created when the principal is applied, providing oil flow through the bearing.
 

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Richard Knight said:
Henk, To answer your question the block half of the bearings use a short longitudinal groove from the oil hole. This distributes oil across the face of the bearing. This works well, it just may be different than what others do. The oil creates an oil film and oil pressure from the molecules rolling over each other. Rick.
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Rick, your idea potentially has merit, but where I think Russ and I would have concerns doing as you have suggested is that you potentially have a weak area in the casting by making a longitudinal (perpendicular) groove as opposed the engineered diagonal groove?

Additionally, I feel by using wells on either side at the parting line, you have the ability to have a reservoir of oil on both sides and the diagonal groove allows for the oil to contact the pin in more areas providing a greater amount of lubrication. How much additional longevity 'one would see between the two methods would be very difficult to determine.
 
I have an engine that was rebuilt by Richard (Rick) Knight back when he was still doing that work and it is a terrific, great running engine. He had a very good reputation as an engine rebuilder "back in the day." YMMV
 
Brent, It is not an "idea" it is a fact. I had my shop from the early70's until around 2000. I used hundreds of rods with circular annular grooves and babbitted and align bore hundreds of blocks with what I have described. Back when engine oil was more like road tar the grooves and oil wells served an important part of lubricating the bearings. If you look at the design of bearings and fluid dynamics and modern oil all those grooves are not such a good idea. It is not a maybe it will work, it does work and work well. Breaking up the oil film is not what you want to do. I am just saying bearing design and engine oil have progressed some since the 20'-30's. I worked on all kinds of engines from dirt track racers to indy and saw the evolution of oiling syste's first hand. If you machine for oil clearance and supply oil it will support the journal, it just does. I think what you do is just wonderful. You are lucky to have the KR Wilson tools. I came at this from a little different perspective. Rick.
 
Since I started this thread, I’d like to thank everybody for their contributions ! This may change the way of thinking about Model A Bearings, which is good. The original design - being a purist I hate to say this - Is not conform hydrodynamic theory ! Whatever you do, after rebabbitting and alingboring, LEAVE THE LOWER CAP ALONE !

Henk
 
hazelhoff said:
Since I started this thread, I’d like to thank everybody for their contributions ! This may change the way of thinking about Model A Bearings, which is good. The original design - being a purist I hate to say this - Is not conform hydrodynamic theory ! Whatever you do, after rebabbitting and alingboring, LEAVE THE LOWER CAP ALONE !

Henk
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I should clarify that my earlier comment regarding lack of grooves on Model B engine with 40,000 miles of use applies only to the lower caps. The upper caps did have singles grooves per the Ford blueprints as well as oil reservoirs at the parting lines. These bearings did perform quite well with such an arrangement.
 
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