25mpg 71 C10. Need Your Help!

[bill3rail]

Originally Posted by joeydurango

I figure eight years later, the PO either got what he wanted, decided to drive it as is, or sold the truck...

His last activity was Jan 2017... Yeah, it's been a while!

[Jrainman]

my 68 came with a 81 4 bolt 350 transplant engine and TH400 , EB 650 Carb , I put a 308 in the rear unknown mies on the engine when I bought it , i put about 52,000 miles on that engine before the head gasket went , if I kept my foot out of it on my 70 plus miles trip each way to work i would see 19-20 MPG . I know run a L31 crate engine with a 200 4R and Fitech with the 308 rear and if I kkeep my foot out of it witch is hard to due on my daily drive to work i can see 23 MPG if they let me run the speed limit .the first 40 miles of my trip I run 55-65 MPH the last 30 plus miles is a all out war every morning on the highway at 70 your being passed pushed and high beemed, I proberly average about 80 MPH on that last 30 plus miles and getting 18-19. MPG. I agree with going with a LS swap, I think you cant beat the LS for ending up with a well rounded powertrain with performance ,longevity and MPG.