P51 valve sizes

Is it possible to run a 2.3 intake and a 1.8 exhaust valve in these heads?, and if so what kind of bore would you need? I thought I read somewhere Kasse move the valves a little more compared to the SCJ heads.

Ernie,

I do not believe that's ever been done yet on a set of P-51 heads. They come standard with a 2.250" intake valve and a 1.760" exhaust valve. We have been putting 2.300" intake valves in some the heads that I've done, but have been leaving the exhaust valves at 1.760". They seem to flow okay and make good power on the dyno with this combination. Therefore I really don't see the need to go up in size on the exhaust. At some point, the valves would start clipping each other, as they did on several hundred sets of the old A-429 heads from FRPP.

The P-51 heads have the same valve relief locations as the FRPP SCJ heads. I believe wht re referring to is that Jon changed the cant angle of the rocker stud slightly, as compared to the SCJ heads.

Hope this helps,

Charlie

Tennessee Bullitt wrote:Is it possible to run a 2.3 intake and a 1.8 exhaust valve in these heads?, and if so what kind of bore would you need? I thought I read somewhere Kasse move the valves a little more compared to the SCJ heads.

I have run a 2.280" intake valve with a 1.800" exhaust valve. Those sizes were chosen in order to keep .030" between the valves when they were at rest on their seats because I knew that would be safe. Closer together would be an accident waiting to happen, in my opinion.
When a 2.300" intake valve is used, the valve seating area on the valve seat within the head is on the outside edge of the steel inserted seat. A 1.800" exhaust valve seats almost out that far.

Thanks Charlie and Randy.