Manifold heat cross over physics and benifits

carb manifolds vs efi manifolds are too different beast. most plastic manifolds I see are efi. I think for a carb you need heat to keep the fuel atomized. I like to keep the exhaust crossover and use a 195 thermostat if I intend to get maximum mpgs with the motor. If you want power drop in a 160 thermostat and block off the crossover.

I speculate a heated carb spacer would end up hurting in the summer but maybe helping slightly in the winter. Might be worthwhile if you had a on off valve so you could turn it off in the summer. Not sure if it would really be worthwhile for someone in the states (besides alaska).

Air gaps, honestly they probably are horrible for mpgs. Great for performance though. If anyone has heard of an air gap getting good mpgs prove me wrong.