Hello guys, I'm new here, my name is Eduardo, from the north of Mexico. I have a Dodge Dart 1973 with a slant 6 225 engine. I filled my tank and did a 3hour long road trip this morning and surprisingly, I ran out of gas. I thought the gas was leaking somewhere but it wasn't. Then I checked its fuel economy and found out that it gives 16mpg, which is too low on my perspective for a slant 6.

Anyway, I did some more research and it seems that the 318 has better fuel economy than the 225 with 22mpg. My question is, is the swap as easy as taking away the 225 and putting the 318 engine? or my stock transmission, alternator, etc. are not compatible with the 318?

Thanks!