915 head "Valve Question"

[02sixxer]

I pulled the valve cover and the casting on my 915 head is 2780915-2.

When I search this it says the valve size is 2.08 intake and 1.74 exhaust. However, I have heard that is not always correct and that the 915's often have small 1.60 exh valves. Is that true or is that a different casting number.

If the exh valves have not been replaced what size are the 915 valves with this casting number?

Thanks

 

[RustyRatRod]

It depends. The same head casting number came both ways. with the 1.60 and the 1.74 exhaust valve. They are the same head otherwise. To my knowledge, there's no way to tell without pulling the head off.

 

[horsehead]

Hi 02.The 1967 magnum head had 2.08 int. 174 exh.The 383 had the smaller exhaust. I believe same port volume just a smaller exh.valve.That said you can open up the exhaust to 1.74 and have a fresh seat on the 1.60 915s.

 

[Dustbuster]

Unless it it clearly stamped HP you have 1.60 exhaust valves. The HP's had the 1.74". Both had the 2.08" intakes however