Whattya getting for Mileage?

[Bandit76]

I have been driving my 79 Jimmy as a daily driver and can't help but wonder if I can better my gas mileage. The tank was filled and I am officially starting my test for my vehicle, but I am wondering what the absolute best people have is.....and what they did to get it.

My latest run for me is in the 11-12 mpg range. I know I won't get 60 on gas, but a little better would be good. Where do you start?

Exhaust, ignition, throttle body spacers, propane system, etc? I want my rig to be a daily driver capable of the odd weekend excursion. I see a lot for race applications and see a lot of OEM replacement stuff, but what is actually GOOD and reasonably priced for the performance it brings.

Peace

[1976K5CHALET]

Keeping the stock gears and stock 26" tires will be the best help. Might not look cool but a cheap way to get maximum mpg.

My 79 rides on 35's...4.10 gears and has been converted to tbi and i get 11-12 mpg.

Allthough costly...a 700R4 conversion from bowtieoverdrives.com is the next step...and or a FI swap.

DW

[Bandit76]

So, 31's from my burb would be a start. Keep the mudders for a rainy day.

The burb has a 700R4, but that will probably end up in the pickup mated to its original motor.

For the TBI swap where did you put the fuel pump?

[1976K5CHALET]

I also average 11-12 in my chalet...which is my daily driver to the oilfields. Recently due to a nasty location i had to buy some mudders for her. Big decrease in mpg...its a rolling resistance thing...more energy is required to get the mudders to roll than my wrangler RTS's...

The tbi swap is easy in a K5 as the 87-91 models were TBI'd from the factory.
I bought an aftermarket tank that has a STEEL baffle instead of the sh--y phenolic plastic one gm used that allways comes loose in the tank. Rockauto.com sells the tank for around $95. Then if you watch ebay you can find aftermarket sending units for about the same price which is half the gm price. Next is the fuel lines themselves...you can either scrounge from a donor and go all gm....or you can have a good welding shop cut of the gm saginaw fittings and weld on AN fittings and build your own lines to the tbi unit...


If you watch ebay...a seller named RAGGED has been selling tbi parts since 1998....i've been one of his customers since 98-99...he sells 7747 ecms...and $65 sensor deals where you get all the sensors needed to make her run...used yes..but cheap compared to over the counter. G

Gotta run...sold the house and i am towing out my small fleet of K5's today and the toolbox (requires flatbed wrecker to move).

Doug W.

[evan]

This thread might be worth reading. http://67-72chevytrucks.com/vboard/s...hlight=mileage

[Bandit76]

Thanks for that Doug. Good luck with your move.

[longhorn71]

I get about 14-15mpg but it is an 87 and has 31" mudders and a 700r4 overdrive and alot of miles put on it....It also sees alot of offroading so the 4x4 dont help

[bgeraurd]

I get about 18/20 in my 1984 Jimmy on 33s with a turboed 6.2. Then in my 1989 Blazer I get around 9/12 with 4.56 gears, 35" boggers, cam and bigger injectors.

[Bandit76]

More feedback is good!!!!!

I am into my third week of my new job and the mileage is getting better. Guess I burned out some carbon opening her up on the highway. 13mpg last run.

Looking at a spacer for the carb. Edelbrock....haven't looked at the cfm...witha manual choke. Probably switch to electric choke for fun or drop in my carter 600 when my other truck gets here.

Looks to be dual 2" exhaust with stock manifolds and aside from the intake and carb, all else is as it were in 79. I'm thinking a little better mixing and a nice new coil, plugs and helicores to eliminate the spark issue.

What else would you do? I'm doing math and finding that my truck vs gas mileage vs new car with better mileage will be the same as any major mod to this motor cost wise.

Peace

[Zoomad75]

I'm lucky if I get 8 mpg. But thats with 35's and 3.73 gears, no OD. I don't really know because the speedo is so far off with the tires.

What I do know is a 50 mile on way run will consume about 1/4 of a tank. So, with a 31 gallon tank. 1/4 tank is 7.75 gallons so 50 miles on that much fuel works out to 6.5 mpg. Then again, with the giant dent in the fuel tank, I might have to suspect it's accruacy too. All I know is that pig sucks fuel. Thats even with a well tuned q-jet, MSD super HEI dizzy, headers/duals and open element air cleaner. Course I normally run at 70-75 on that trip and the tach is spinning about 2500. I know slowing down would make a difference.

[special-K]

I`ve owned my`90 since it was new.WOW!,that`s 16 years!Anyway,I don`t know,I`ll have to check and get back to you on that.

[Bandit76]

Well, this weeks test went to $hit. Icy roads left me idling and crawling in bull low for the last mile and a half. 40 extra minutes for my commute. Snowed, melted and froze. Good combination.

Mud T/A's on the ice.

I've been keeping my revs conservative. Do about 55 mph at the most and a little stop and go through towns at 35, so it's not steady pace.