Stay w/ 289, 5.0L (302), needs more support, such as computer, other electronic controls, emissions, etc.I would estimate 2 bbl. 289 in good tune @ 15 MPG, 302 @ the same, maybe a bit better.

There is no such thing as MPG on any automobile earlier than 1980. They were not built with that even on the tip of their tongue, fuel prices were below $.50 back then, they were built for power. you cant have both

Keep the 289, it is a sweet motor and oh so right for the '67 Cougar.

Yeah, your fixing to get into a mess with that 5.0L since it needs a lot more electronics to make it run right. Can't believe you even considered that.

Peter ^^^ keep it going.

How much MPG does it get and between the 5.0 and the 289. If it helps it is a Auto Trans im restoring the cougar so i have the 5.0 from a 92 Mustang. just can't decide on which engine to put. So any help thanks in advance.