Extra main bearing oil holes

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Model T Ford Forum: Forum 2017: Extra main bearing oil holes
Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Sunday, November 05, 2017 - 04:31 pm:

I am wondering if it would help or hinder the life of a T engine if I drilled a second oil hole in the center and rear maim.
How could it not help?
I am putting another engine together and the crank is still out.
Very tempting to drill an 1/8 inch hole in the top half of the center main. On the back side, same on the front main.
Maybe rear too. . .?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Sunday, November 05, 2017 - 04:56 pm:

I for one am looking forward to the replies, I am thinking about adding one to the center, rear side too.


Top of pagePrevious messageNext messageBottom of page Link to this message  By gene french on Sunday, November 05, 2017 - 05:51 pm:

Aaron and Mark :
I have made a long shank countersink that I use to make a small "funnel" in the oil inlet holes ...long enough to reach down thru the cylinder bores ...can't say for sure that it has helped ...but , it has not hurt anything...always an optimist...gene french


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Sunday, November 05, 2017 - 06:35 pm:

Sounds like a good idea to me. I can't see what it could hurt.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Will Copeland - West Melbourne Florida on Sunday, November 05, 2017 - 06:49 pm:

It’s just me but I feel that when the engine is at speed I think there is so much oil being thrown around in the crankcase that there is a oil fog coating everything. 5 quarts of oil in a confined space being tossed around by rods and and magnets at 900 RPM has to turn any air cavity into a oil filled fog.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Frost on Sunday, November 05, 2017 - 07:00 pm:

Great idea. I think the extra oil would be good at start up, when most wear happens. After the engine stops the "funnel" filled with oil could coat the bearings.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Sunday, November 05, 2017 - 07:03 pm:

I,ve come across early blocks with a extra oil hole in the centre main.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Sunday, November 05, 2017 - 07:44 pm:

You may be right Will, I agree with you, but still I think it would be worth doing.
Thanks for posting that picture Frank.
I'm gonna do like Gene does , make a long shank and get er done.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Sunday, November 05, 2017 - 09:17 pm:

What will says about an oil fog everywhere in there is more reason to use a light oil like 5-30.
It's a splash system, you can't splash roofing tar.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, November 06, 2017 - 04:10 am:

Ford used two oil holes in the center main until August 26, 1914. The reason they discontinued them was likely cost - they couldn't see much difference in wear, but now after 103 more years of experience we know they wear eventually, so I drill a hole there on my engines and countersink for more flow.

http://www.mtfca.com/encyclo/doc14.htm
AUG 26 Ford Archives
“Start one hole in center main bearing.”


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, November 06, 2017 - 08:41 am:

Wish I could post pictures I have but can not find on my PC from information in a book I all so have in my stash.

It explains why oil should enter in the middle of the unloaded side of a splash oiling system and why the pressure is the highest there. Pressure drops off at each end of the bearing with leakage.

Compression, exhaust, and power are on the cap not the unloaded block---intake is the one cycle on the block.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Monday, November 06, 2017 - 10:34 am:

Paul

With respect, check the book again...the pressure is lowest at the top where the oil feeds. The pressure will be highest at the wedge or leading edge of rotation within the bearing (which will be within the cap) at the start. In operation, the rotating shaft will be slightly off center toward the direction of greatest pressure applied, and it is at this location that pressure will be highest. As the oil flows toward the ends of the bearing, it's pressure drops as it exits. Thinking about this for a moment shows how important the cut reservoirs in the center/edges of the caps are for maintaining a constant line of oil to feed into the wedge zone. These areas are the chamfer cut by the guy who poured/bored the caps...it is an incomplete chamfer that doesn't quite extend to the edge of each end of the cap, on both sides.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, November 06, 2017 - 01:02 pm:

Scott

I think you are talking about Hydromatic action---wish I could post a picture to save printing so I will print the answer in the book

The hydromatic pressure that is built up in most plain bearings and forms the oil film that makes possible their operation under heavy loads is called hydrodynamic action or hydrodynamic lubrication. This occurs because the lubricant has a tendency to adhere to the rotating journal and is drawn into the space between the journal and the bearing. Because of viscosity or resistance to motion of the lubricant, hydraulic pressure is built up in the lubricant film. Pressures as high as 600psi are not unusual in well designed bearings. Hydrodynamic action occurs in plain bearings as the shaft rotates. When at rest, The journal slowly squeezes out most of the lubricant. A condition is reached where there is metal to metal contact between journal surface and the bearing liner. When the journal begins to rotate it has a it has a tendency to climb up the side of the bearing. A further rotation of the journal causes oil to be drawn into the clearance space between the journal and the liner. The journal is lifted by the oil film. As speed is increased higher oil pressure is developed.

Need to locate the book in my stash I can tell you it sure gave me the reasons for triple gear issues


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Monday, November 06, 2017 - 01:30 pm:

Paul

I agree 100% with your info above (what I took exception to was what seemed to be your statement that pressure is highest at the oil fill (entrance) hole to the bearing, and that is still wrong if that's what you meant). And I agree with your original statement that pressure drops off at the edges as the oil escapes. The highest pressure is at the wedge when starting (lowest at the fill hole) and then normalizes when running.

I am not trying to pick a fight and this really isn't germane to the OP's question, so I think we'll have to agree the book's accurate and maybe I am misunderstanding your original post :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Monday, November 06, 2017 - 02:39 pm:

I have trouble conveying thoughts with print no issue at my end!
Found the book I was using for information---one part says regardless of grooving it is important that such grooving be confined to the unloaded portion of the bearing surface. if the grooving extends into the loaded or pressure region the oil film will be disrupted, and boundary lubrication conditions will exist.
Interesting it says for grease it should enter the loaded side of the bearing.
Re reading my first post I should have wrote lowest----not highest pressure sorry Old age LOL


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Monday, November 06, 2017 - 03:34 pm:

Paul

It's all good!


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