Canadian C5-RA heads 39-41?

[Newc]

Hi all; I wonder about putting a pair of C5 iron heads on my Canadian C7 engine [59AB type]. First the C5 heads have been cut so as to have a 2 3/4" diameter dome [Small], then will the valve pockets clear the later eng's valve angle? All this dancing is for a '42 CMP Canadian truck. Thanks Newc

[Bruce Lancaster]

C5 is a type of PN prefix I haven't see that early before...it would indicate 1945 so very late for one of those. I previously had only see Canadian civilian 1947 C7RA and a few USA 7RA numbers...
Anyway, weren't all the CMP 239 Mercury powered? I would think with small domes remaining they must have been milled. I would have expected them to be for the 1942 type engine, early angles, but with a previously unknown head released in '45, might they have been for an early postwar release of a 59 type engine?
The C7 heads are clearly late type, the iron C7's equivalent to 59AB and the aluminum one somewhat higher compression than any American equivalent.

[russcc]

I have friend that has a doming tool, and can rework them if needed.

[Kahuna]

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Newc
Your best bet is to install them loosely and see what, if any, interference there is and modify accordingly. Depending on the engine displacement, they might be fine as far as compression ratio.