Milling a 170 Head For a 144 Engine

Due to broken manifold bolts in my 1960 144 c.i. cylinder head, I am swapping it out with the 170 c.i. cylinder head from my 1962 Mercury Comet. With mild cleaning in the combustion chambers and intake + exhaust ports, I currently have 54 cc at all combustion chambers (#6 is a hair under 54 cc). From looking online, the 144 combustion chambers ranged from 44-51 cc and the 170 combustion chambers ranged from 48-53 cc. I have bought an NOS steel shim head gasket for the 144/170, to replace the steel shim gasket that was on my 144 engine. I also read on the Classic Inlines Small Six Cylinder Head Swaps page that typically milling the head .010" will result in an approximate reduction in volume of 2cc's.

I am thinking of having 0.030" milled off (6 cc's) to put me in the low end of the 170 combustion chamber size (48 cc). This will put me in the upper end of the 144 combustion chamber size. Just double-checking before I pull the trigger and have the work done, I will also have the guides replaced and the valves cleaned up.

Thanks,
Tom - BORN 2L8

Howdy Born:

It's good to see that you have done your data research and established to volume of the 170 head at 54 cc. A mill cut of .030" is right on. I'd also suggest that you request that your machinist take a 30 degree back-cut on the intake valves to increase flow. It won't cost much since the head is already down for R & R. The good news is that the '62 170 will have slightly bigger intake valves at 1.52" and slightly greater intake tract volume.

Keep us posted on how it comes out.

Adios, David