The 67 cylinder heads are the same valve sizes as the 68 heads , 2.14 intake
and 1.74 exhaust but the 67 are a closed chamber style. Only the earlier big
block engines used the 1.6 exhaust valves, though truck engines may be an
exception to this but were not driving trucks here, were driving Imperials.
The closed chamber has a smaller volume than the open chamber - I dont
recall the exact cc. offhand - so in a given engine the smaller chamber
does increase the compression somewhat, but the valves are unshrouded by the
open chamber on the later head and improves the breathing a bit - which in
the case of a car the size and gearing of an Imperial is a somewhat moot
point.
Remember, ANY B or RB cylinder head will physically swap, (with max wedge
heads being somewhat of an issue because finding intakes for them arent easy
and no B engine intake will match the ports sizes ) and any engine of this
family can use the " magnum " heads or cams , so when someone says they have
a 383 magnum or a 440 tnt, you can easily do the same with the right heads
and intake. The exception to all this interchangeability being the 383 and
400 low deck blocks and the intakes for them are narrower, so you cant swap
intakes from RB to B engines.
As far as compression, dont be surprised if you were to do all the
measurements and calculations and find your 10:1 engine is really 9.5 to 1.
The factories back then tended to use a lot of published figures , as they
say in the informercials " your results may vary"
Mikey
62 Crown Coupe
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