340 X heads- Will they fit on a 318-3?

[polarman]

 I have a 73 Brave with a 318-3. The umbrella seals are shot and this thing blows smoke like a James Bond 007 smoke screen when coasting downhill. I'm sure the valve seats are hurting too, given the age of this all original engine. I have a pair of 340 X heads from 1970 (the good ones). Knowing that the 318-3 is a truck motor with enhanced cooling, my question is: Are 340 heads compatible with the 318-3 engine?

[polarman]

Same question with the cam shaft and intake from an LA engine. If I am able to use the 340 heads, then I would use the 4 barrel carb and intake that I have on the shelf, which would require a change in cams to run well with a 4 barrel carb.

[Xbird]

they'll bolt on, but you have to do some pretty thorough analysis of the match of the smaller 318 bore to the 340s wedge chamber designed for a bigger bore block and bigger valves. gotta work out potential valve shrouding, change in compression ratio etc. Viable plan, but you'll also have to work up a good cam selection once you've figured the details and any potential machine work needed in order to make the power where you need it.

[polarman]

That's what I was thinking. My concern is that the cooling jackets won't line up with the enhanced cooling system of the 318-3. Thanks for the reply. My initial google search of 340 heads on a 318-3 block yielded no information whatsoever. These 340 heads used to reside on a 1970 318 passenger car block from a Plymouth Fury, and that set up absolutely screamed in a 68 Dart with the "Hemi grind" LA cam. It seems hard to find information about the differences and similarities of the 318-3 and 318.

[Rickf1985]

Aren't those closed chamber heads?