Model NH valve angle

[Peter_L]

Hallo,
is there anybody who knows about the valve angel for Model NH,1957 s/a, with alloy-head ?
After welding I have to re-bore the valve-seat and the valve-guide borings.
Will be glad for any support.

[nevhunter]

Not an easy job. Put the new seats in by liquid nitrogen. The heads are pretty soft. Don't know the precise angle but both valves should be the same.
Dial off the best guide bore if you don't get an answer. Nev

[david.anderson]

On a 57VH the included angle is 76 degrees with the valves inclined from the vertical at 38 degrees each. Can't be exact with the NH but may be the same. (same rockers) The VH guide boring is shown at .624" - .625".
David

[Peter_L]

Thank you all for the answers! David, I think your right. After inserting a pilot bolt into the valve-guide bore the rough measurement from vertical coresponded 38 degrees. Next step will be to set up the head on a milling machine table.
I will continue to report.
Peter

[Peter_L]

I hope it works...

[Peter_L]

First cut at the new valve seat.
Interference valv seat to alloy head: 0,05 mm.
I hope it works.

[nevhunter]

MY only comment is you have gotten out to a big diameter on the new seat. Probably unavoidable. That means you don't have much "Give " on the seat. You can always revert to ALL Iron. I'm not a great fan of those heads. Nev

[Peter_L]

You are right. I didn't know that the steel valve seats were casted into the alloy with a interference-angle of about 5°....
And even more, the Ariel 500 cc valve seats were both casted into the alloy as a single spherical cap.