305
 

'85 high sierra is getting 11.9 MPG after carb rebuild. Sure thought that little motor would do better than that.

Re: 305
 

What gears are you running? What transmission? What size tires Those three play a big role in gas mileage.

Re: 305
 

Pretty much the same as I was getting. '85 C-10, 305, rebuilt QuadraJunk, 350 turbo, 2.73 gears... Gas mileage and these trucks don't mix. I don't know why so many people are suprised their mileage isn't good.

Re: 305
 

700R4 tranny with 235/15 tires.

Re: 305
 

My 87 GMC had a TBI 305 with the 700R4 and 235s and it would get 16mpg if I was easy on it. For a carb'd motor and depending on your driving style almost 12 mpg sounds average.

Re: 305
 

Unfortunately that pretty much is the norm. You are running atleast an OD transmission and stock tires. What gears? If you are running something like a 2.73 and all you do is stop and go city driving, that would hurt mileage.

Re: 305
 

My 86 swb with a carb'd 305/700R4 2.73 rear on 275/60R15 tires gets 17mpg mix of city and highway. Only mod is a catback flowmaster. I don't go to easy on the gas either.:burnout:

Re: 305
 

I get 13mpg with a mix of around town and highway. Holley carb, performer intake, headers, flowmasters, and i don't go easy on it.