67S Port Size

[JB]

I recently acquired a '67S motor that appears to be a very low miles, correct, factory built motor. This is an aluminum case, 911/02 motor. Upon measuring the head ports, I found that the intake port measures 35mm at the inlet and the exhaust port measures 33mm at the outlet. This is in direct contradiction with the specs for ports given in Bruce Andersons and Wayne's book of 36mm Intake and 35mm Exhaust. The valve sizes measure 42mm Intake and 38mm Exhaust which agree with their books.

My question is: Does anyone know for sure (measured actual head ports from a 67S) what the correct port size is? According to the spec books, there is no other head that shows the configuration found on my motor.

Thanks,

JB

[john walker's workshop]

i measured some 6/69 S heads, and they are 36/35. that's all i have.

[snowman]

Someone was sleeping at the factory. The ports start out at about 32mm as in the T engine and are bored out to final size, maybe they missed the exhaust?

I wouldn't be very concerned about it though as the heads flow good enough anyway. But if you are really concerned., buy a cheep die grinder and one cone shaped carbide burr. Use the gasket to mark the hole size with a magic marker. Carefully grind out the port to size. Note only the very inlet point is undersize, the port is correct thru most of the head as cast. In other words only the first 1/2 inch or so is undersize and the rest of the hole is ok.