Concerning valve seat width, valve seat contact length, and contact location on the seat:

If I want to reduce the valve seat width and/or move valve seat contact in on the valve, should I run a .030 degree back cut into the 45 degree seat?

One the other side of the seat contact, what if i reduce the diameter of the valve to move the seat contact more towad the outside of the valve and/or reduce the contact that way?

It seems like valve seat contact should be less than valve seat width.

What are good valve seat contact length, seat width, and seat location recomendations, intake and exhaust? What about valve margin length and treatment (chamfer or radius and size)?

Does the same apply on a nitrous motor, say 200 shot or less (larger seat and/or margin on the exhaust valve)? I'm not interested in larger exhaust valves.

What about necked down valve stems vs increased power. I'll assume it may help flow perhaps over the .500" lift range, but not necessarily low lift flow?

Any suggestions on DIY valve shaping?

 

Do you have access to the machinery required to cut seats and grind valves? Are you just asking for knowledge, or do you plan on trying it?

 

http://stockcarracing.com/techarticles/78578/

http://www.automotiverebuilder.com/ar/ar119854.htm

Rich

 

Thanks for the info rich.

I'm still interested in how to thin the seat contact, according to this information you can run the 30 degree back cut right into the seat contact (leaves no flat area without valve contact). That's ok?

I'm mostly just curious what's been tried and what may be best.

I don't have any tools to shape valves (grinding equipment). I do have access to a machine shop and tool and die makers (for advice). I could ultimately reshape a valve but would not attempt anything on the seat.

Additionally, Manley does have a chart to show percent increase in flow with necked down valves. Manley also offers a 7 mm thin stem valve, any one have any information on who is using this valve including the advavtages.

 

I heard Cup used to use or currently uses 7mm valvestems.