!!! Mpg !!!
 

This seems to be more of an issue these days. I am looking forward to getting my Blazer on the road soon and I dont know what to expect for gas mileage. I am currently running a mild 350 w/ a 600 Holley backed by a TH350. Right now I am running 33's and 3.08 gears(going to 3.73,s). I would expect maybe around 12 mpg..... is this close? Gas has spiked to $5.29 a gallon b/c of the hurricane and its not looking good right now.

Re: !!! Mpg !!!
 

Maybe 12mpg, maybe closer to 10mpg.

Our trucks are basically like pushing a brick through the air, having zero aerodynamics, being carb'd and not having overdrive to slow the engine rpm's down all add up and work against the mpg issue of these old classics.

Welcome to the board, we're all in the same boat. :metal: :chevy: :gmc2:

Re: !!! Mpg !!!
 

My personal best was 14 with 3.08 gears and a 4 speed.

Re: !!! Mpg !!!
 

I get around 12-14 with mine. 100% stock engine, 3.07 gears and stock 235/85 16's.

Re: !!! Mpg !!!
 

10-12 is pretty common.I`d lose that Holley 600,though.That`s gotta be the worst carb they ever made.You`d be better off with a 650 or one of thier Avenger series.O/D only helps at hiway speeds.It`s all about engine speed.With O/D you can go faster and use the same amount of fuel or drive slower and use less(in high gear).Without it,I just don`t drive over 65.I`d say keep the 3.08s.They are like having O/D.As long as you have the torque to get you rolling they work fine and love rolling you down the hiway.A manual would help alot.I get 12.5 in my`72 K2500 350/TH350/33s.I got the same in my`72 K/20 400/4spd/35s.

Re: !!! Mpg !!!
 

My72 with rebuilt 350, mild cam, stock exhaust, HEI, 4spd, 33"s, and 373 gears = 13mpg in town and 14-15 highway as long as I stay at or below 65. Running Edlebrock 650 and edlebrock intake. I believe I could get a wee bit better without the edel intake, with 308 gears and 31" rubber. Big tires, headers, custom intake, 373 gears, can all hurt your mpg-low end torque. Huck