452 Head Valve Question

[Fly Boy]

I read a article stating that if you take a set of 452 heads and install 2.14 Intake valves and stay with the stock 1.74 Exhaust valve the head will make more power. The reason is when the exhaust seat is cut for the larger 1.81 valve it gives the short radius a sharper turn causing turbulence. Which will lower the heads efficency. And you will cut through the induction hardening of the seat. The heads are for a street car and they have a mild port job. Is there any trouth in this or should I install the 1.81 Exhaust valve. Thanks for any input on this question.

[fast68plymouth]

if you only have a mild port job on the intake side, then you wont see any benefit from putting in the larger ex valve, and yes you will break through the surface hardening. when you get the intake flow up into the 280cfm range, the its necessary to go to the bigger (1.81) valve. if you are only running a mild cam, and are primarily using it as a street car, then just leave in the 1.74's.

[Fly Boy]

Fast68, The heads are still on the work bench. I have a 440 with a CR of around 9.6, the cam is the Hughes 3038 and I am using a set of KB quench doam pistons. I am about to complete the porting and wanted to know about changing the valve size before I finished. I will be running a 6-pack intake system on the car.

[This message has been edited by Fly Boy (edited November 19, 2000).]