Valve seats on the original T

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Model T Ford Forum: Forum 2012: Valve seats on the original T
Top of pagePrevious messageNext messageBottom of page Link to this message  By Bud Holzschuh - Panama City, FL on Sunday, November 11, 2012 - 06:38 pm:

Modern engines sometimes use three different angles in the valve seats.

When T engines originally left the factory, did they use multiple angles or just a single angled cut?

Thanks
schuh


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Clipner-Los Angeles on Sunday, November 11, 2012 - 07:05 pm:

Single cut, but I believe many re builders are going to Multi angles.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky, Lytle TX on Sunday, November 11, 2012 - 07:08 pm:

I believe it was a single cut--All eight at once. Another tidbit; The cylinders weren't honed with a cross-hatch. After the bore was cut, it was brought to finished size with a roller swage. This left the bore perfectly round and near a mirror finish.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Shirley on Sunday, November 11, 2012 - 08:00 pm:

The multi cut seats are done so that the finished seat face will be .060 on the intake and .080 on the exhaust. The bottom cut being 70*, the seat face 45* and the top cut at 30*. Two cuts, 45* face with 30* on top will let you get to a 1/16 face witch works fine on most of the blocks I've seen.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Sunday, November 11, 2012 - 08:45 pm:

Bob Shirley - Something in the back of my head make me think a three-angle valve seat with a 1/16" seat face is about ideal but I'm sure no expert!

I mention this because I think it is more important than most folks realize, especially in the case of exhaust valves. The reason 1/16" works well is because the more narrow the valve seat face, the more pressure per contact area, and that is critical, because in the event a piece of carbon becomes momentarily lodged between valve seat and valve face, you need enough pressure per sq. in. to break the piece of carbon so it does not stay in place long enough to cause the valve to burn. On the other hand, the only time an exhaust valve cools is during the short time the valve rests upon the valve seat (hopefully wide enough) which allows heat from the hot valve to radiate thru the valve seat face and into the cooler engine block. So, I'm sure that the width of the valve seat is kind of a compromise. There must be one certain size that is that "ideal" compromise, and I'm sure there are folks on this forum that know more about it than me and I hope one or more of them will "chime in" here. I do still think that 1/16" is pretty close though,......harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Lee Frost Pierce on Monday, November 12, 2012 - 01:30 am:

I use the 3 angle seat This keeps the carbon from building up on the valves Also increasing
the valve spring pressure also helps.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Clark - Glendale, WI on Monday, November 12, 2012 - 12:22 pm:

So, from the factory there were no "valve seats" that were replaceable correct? They were just ground into the block?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Monday, November 12, 2012 - 12:26 pm:

Correct Bob.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Clark - Glendale, WI on Monday, November 12, 2012 - 12:40 pm:

Excellent! Thank you Jerry!!I assume the valve guides are the same way? Sorry for the questions. I build a lot of motors for the race car and it has replaceable seats and guides so this is kind of new for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Evan Mason on Monday, November 12, 2012 - 12:47 pm:

IMHE, The three angle seat is used to do two things: It can be used to reduce the width of the seat contact area and also can be used to center the seat contact area on the valve face.

When a seat is ground several times, the seat widens, the seat goes deeper into the block (in the case of a T) and the contact area on the valve widens and the location of contact can shift toward the edge of the valve. The three angles can be used to correct for these changes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Monday, November 12, 2012 - 12:51 pm:

Also correct Bob. The guides are just reamed in the cast iron block. They could be sleeved back to standard in a rebuild I suppose.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Harris from Long Beach & Big Bear on Monday, November 12, 2012 - 02:05 pm:

A lot of engine rebuilders grind the seat to 45 degrees and the valve to 44 degrees, that way there is very little contact and it is at the widest point. The wear factor simply makes a convex contact point and it lasts very well if you have good seats and valves. When I had our 1912 engine valves redone because I burned a valve, they said the block was made of a very soft type of cast iron. I had stainless steel valve seats put in back in 1965 and the whole job of new valves and seats was under $150 but that was long ago.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Clark - Glendale, WI on Monday, November 12, 2012 - 02:48 pm:

Thanks Jerry.. I'll get out the seat cutter and fire up the valve resurface machine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Monday, November 12, 2012 - 03:02 pm:

And yet 2 more things are learned. Seats & guides just ground into the block. Wild.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett on Tuesday, November 13, 2012 - 08:48 am:

Somewhere I have a photo of a seat cutter which is ground to a slight curve, so rather than make 3 cuts you get the 1/16 contact where the flat valve meets the curved seat. I was told it was a Ford tool.

Not having one of these, when I do valves I use the 3 cut system on the valve itself, and it works well for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, November 13, 2012 - 09:22 am:

Not really wild, it is normal for any cast iron cylinder head or block to have the valve seats and guides integral with the head or block. This is superior to a separate guide or valve seat in any number of ways, from a standpoint of ease of manufacture and also from the perspective of heat transfer.

The valve should be "proud" of the top of the block for best performance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roar Sand on Tuesday, November 13, 2012 - 09:33 am:

Royce, you are correct. About 80% of the heat in the valve is transferred to water via the seat, the rest goes to the guide, and the rule of thumb is that the temperature of the valve increases 100 degrees when you put in a seat insert instead of seating directly on the block or head material.
FWIW
Roar


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, November 13, 2012 - 04:14 pm:

Roar,

That is why I like to use oversized diameter valves instead of installing seats or guides. I have 1.66" diameter valves with 11/32" stems in my 1915 touring right now. They are cut down stainless steel Fordson tractor valves.


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