mpg

[greenmonster]

I have a 75 k10 with 350 engine 350 trans and 3.73 gears.My mpg is 6.25.
It has a holley 750 on it and i know it is to big but i think it should do better than that.
If anyone has an idea please help!

[zieg85]

Carb it probably to big.  I would think with that setup you should be able to get at least 12 if your foot isn't to heavy.  Big tires if you have them are a lot of resistance as well.  The lesser the width the better.  Last 4x4 I had was a 72 C-20 350, 4 speed and 4.10 gears and I got 10-11, dropped to 9 when I was pulling my trailer.

[greenmonster]

I have 31/10.5/15 tires on it.So you think the carb is the main problem.12 mpg is what I would like.

[123 pugsy]

I dropped a 750 cfm on my 350 and boy did it run lousy. It would bog when I stepped on it. I would definitely change the carb.

[greenmonster]

Mine bogs alittle too.does anyone have a carb they want to trade. Ihave a holley 3310 750 and a holley
650 double pumper. the 3310 i just rebuilt and the 650 worked fine when i took it off a month ago.

[zieg85]

I am partial to Q-Jets.  My buddy is brilliant with tunning them in.  I had a Rochester 2 bbl he had re-jetted and did his thing on my 72 C-10 with a 350 TH350 and 3.08.  I was getting 17 or so and the exhaust pipes were a light gray.  Before it was only getting 10 and there was no indication the carb needed anything because it ran perfect.  He put it on the sniffer and it passed for 1984 emission standards with not one stitch of emission control stuff.  When I raced circle track that is all I ran.

[greenmonster]

I have a weiand stelth intake can i get a q-jet to bolt up or do i need a spread bore intake.

[zieg85]

All I know is the stock stuff, sorry...

[123 pugsy]

I have a weiand stelth intake can i get a q-jet to bolt up or do i need a spread bore intake.

Performance shops have all the adaptors you'll need.
Why did you take off the 650?

[greenmonster]

it had manual secondaries and it made my truck bog on hard takeoffs

[85MudMonster]

wow I thought my MPG was crappy! I've got an 85 K10 with 305(H) and TH-350, 3.73 gears, and 33/12.50R15's and I just drove it from Shreveport, LA to Springfield, MO (422 miles) and averaged 13.5MPG highway. The motor is all stock, and the only modifications it has is a flowmaster muffler, and an edlebrock air filter assembly. I thought it should get like 15-17MPG highway? Or am I dreaming?

[werewolfx13]

With those gears, tires, trans, and being a carbed 4wd, you're pretty much dreaming to hit 15-17 on the highway..I get about the same mileage you do with a 2.73/350/350 2wd on 235/75/r15s, so you're doing fairly well..

[Fordeatinz71]

wow I thought my MPG was crappy! I've got an 85 K10 with 305(H) and TH-350, 3.73 gears, and 33/12.50R15's and I just drove it from Shreveport, LA to Springfield, MO (422 miles) and averaged 13.5MPG highway. The motor is all stock, and the only modifications it has is a flowmaster muffler, and an edlebrock air filter assembly. I thought it should get like 15-17MPG highway? Or am I dreaming?

when i took my GMC to Shreveport (i have to go to the VA hospital sometimes...gotta go on the 3rd, come to think of it) from Texarkana (about 75 miles), i wasn't using OD and had the A/C on the whole time and cruising at about 60-70 i got 14.  so yea, 15-17 should be easily attainable.  i would have gotten better but on the 700R4 the lockup torque convertor doesn't function until you are in OD...but in OD my truck was a bogfest...being that i have 2.73 gears. 

[werewolfx13]

I suppose if he has a 350c with functional lockup 15-16 would be obtainable at about 60 mph, but it depends on the rolling resistance of his tires, too.. 33/12.50s are a fair bit of tire to turn, depending on the tread pattern and weight, those alone could knock as much as 2-3 mpg off..Cruising at 60 mph with those 3.73s will be a lot easier on gas than cruising at 70+ mph, too..

[Fordeatinz71]

yea, i only have 31's