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What is a good head, intake and carb set up for a 221? Will a newer aluminum intake work, or will the ports not match up? Can I run gt40 heads or will I lose all port velocity? I want to keep the 221 for the gas milage, but a little more get-up-&-go would be nice.
IMO, look for an old 260 4bbl set-up. Or swap a 302 6 bolt and appropriate trans. in its place, but note you need 7" spacing motor mounts, so those need swapping too.
BTW, what vehicle is this for? I believe the 221 didn't start til 1962.
also, the compression ratio will drop too much with 302 heads on the 221.
I have a 221 in my '62 Meteor and like the 221 for what it is, as you already said.....mpg. Nostalgia is nice, too.
I believe the (rare) 260 4Vs used a manifold that was virtually identical to the 289 4V. Since this is a small motor, how about trying a 255 intake and heads? They have unique oval small ports and an aluminum (2V) intake to match. The exhaust pattern is the same as all the small bocks though.
I think the intake runners on a 221 are indeed smaller than the 289 and 302. I don't know how important this mismatch would be with an intake manifold designed for the latter though.