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1953 MG TD valve seat angle?

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mgbrv8 Dave Hetrick
USA   USA
on a 1953 MG TD what is the valve seat angle on the cylinder head??

Dave

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plus4moggie Tom Lange
Bar Harbor, ME, USA   USA
If I remember right it is 30 degrees as stock. I have heard that a three-angle valve job of different specs flows better, but will need to look throuogh my notes to find those angles.

Tom Lange
MGT Repair

LaVerne Avatar
LaVerne LaVerne Downey
Fruita, CO, USA   USA
1954 MG TF "Green Hornet"
1969 MG MGB
1979 Triumph TR8 "Wedgie"
30 degrees is correct. Old tuning instructions say the XPAG will flow better with the 30 degree verses a more modern 45 cut although I have never seen any data one way or the other. 45 would most likely be of value on a super high lift cam.

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crankjournal Avatar
crankjournal Len Fanelli
Yonkers, NY, USA   USA
Yes, 30 degrees is correct, for a 3 angle it would be 30, 45, 60 ish or 30, 50, 70-75? A 3 angle or 4 angle, multi angle or radius valve seat can make a big difference. Also getting rid of “flashing” material around the port and valve seats, and getting rid of casting flaws etc. A 30 degree seat flows better up to .150" valve lift, and a stock T type cam spends much of its duration / time below .150" lift.
However a high lift cam has a lot more duration / time above .150" lift and a Roller cam even more duration / time above .150" lift.
This is where a 45 degree seat outperforms a 30 degree seat, and with a 45 degree seat the valves can be back cut to 30 degrees for even better flow. I am having my machine shop install the Nissan 35 MM exhaust valves and 38 MM 45 degree intake valves at this time.
Len Fanelli
Abingdon Performance LTD.

crankjournal Avatar
crankjournal Len Fanelli
Yonkers, NY, USA   USA
LaVerne it is the duration / time above .150" lift more than super high lift, but higher lift does matter.
Len


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IMG_20130525_172450_846.jpg

plus4moggie Tom Lange
Bar Harbor, ME, USA   USA
Len - can you show us a picture of the combustion chamber with those big Nissan valves? I'm curious to see how they enlarge the chambers to fit.

Thanks. Tom

crankjournal Avatar
crankjournal Len Fanelli
Yonkers, NY, USA   USA
Hey Tom, not yet! Still at the machine shop. However here is a photo of the later larger MG T valves in a chamber unshrouded to the edge of the head gasket. (Use an old gasket as a template) As the intake valve is 2 MM larger and the exhaust 1 MM larger, they are of course 1 MM and .5 MM larger on the radius. So there is enough room for 1 MM on the intake to the side of the chamber.
If the machine shop ever gets it done I will update with a photo. The other machine work that needs to be done is to machine the Nissan valve cotter area to accept the T type cotters.
Len


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unshrouding the valves in the combustion chamber.jpg    36.3 KB
unshrouding the valves in the combustion chamber.jpg

mgbrv8 Dave Hetrick
USA   USA
Gentlemen Thank you very much

Dave



Edited 1 time(s). Last edit at 2019-02-05 04:12 PM by mgbrv8.

mgbrv8 Dave Hetrick
USA   USA
One more thank you and here are pictures of the car in question back when I first rebuilt it a few years ago for my dads 80th surprise party sense then its covered 30k miles. It developed a water leak right next to the guide in one of the exhaust runners when a rust bubble broke through and Im rebuilding another head to swap it out


https://www.facebook.com/media/set/?set=a.10200317614609867&type=1&l=fc6671fdf8

Dave

TD4834 Avatar
TD4834 Bill Chasser
Sacramento, CA, USA   USA
1950 MG TD
1951 MG TD MkII
Nice car! I bet your dad had a big smile on his face. I wish my dad had the chance to drive my TD before he passed on. It wasn’t to be unfortunately.



Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060

mgbrv8 Dave Hetrick
USA   USA
He did Mr Chasser. Im sorry to hear you didn't get to ride with you but I'm sure he watches you enjoy it.

Dave

TD4834 Avatar
TD4834 Bill Chasser
Sacramento, CA, USA   USA
1950 MG TD
1951 MG TD MkII
Thanks. I’m sure he does. Once I get his TD/c finished he’ll get his final ride



Bill Chasser
TD-4834
TD/c-8151
TD/c-16920
TD-19408
TD-24060

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