Re: 13mpg from a 427 TBI?
Yes it in very possible. My 92 4X4 has a 408 Sb with TBI, and I get between 12 and 15 MPG. The chip is the key, and a well thought out combo can make the world of difference. Another engine I built was a 418, with a solid roller under a TPI. It is in a 88 Firebird that gets 17-22 MPG. (17 at 100 mph! REALLY!!) My only question is a 427 from a 63 Vette? I don't think that the 427 was made until around 66 or 67.