maximum milage project

[big10ratrod77]

so my dad bought my truck in 1977 with the intention of seeing how long it would last(the engine and drive train) well 200,000 miles later its mine and i dont like the crappy milage so ive been modding stuff open element air cleaner with K&N filter, duel exhaust(going on tomarow), and turbo mufflers. well heres the twist i cant go inside the engine(he wont let me) like cam, pistons, heads and intake cant be messed with, what are some tryed and true methods of more milage besides maitaince (its been well maintained). im thinkin 1.6 rockers roller tip rockers(thats as far as i can go inside the engine) for more lift to make it closer to a towing cam, and underdrive pulleys, whats some of yalls ideas

[Prong]

Differential gearing. If you run on the highways primarily, keeping the R's to about 2000 at speed helps alot. This is where 3.08 gears are worth it.

[pig rig]

open up the gap on the plugs a little more and tune tune tune the closer its to running perfect the better milage

use some of the old hotrod secrets to get more power
cool your fuel
cool your air going in
cool your carb
put less load on your engine like power pullys or electric fans

theirs lots of little things to do to gain power and milage with out going into you engine

[big10ratrod77]

changing the gears is out of the question but the 3.73 i got aint as bad as 4.10s

also the reason im doing this is couse for fourth block at skool im takeing automecanics and its bout 40 miles round trip all on the highway and its a year long corse so 40 miles X 180 days = 7200 milesfor the skool year not includeing going to work and other places and just going to skool

and i orderd a flex fan also from summit

i need to give it a tune up is what should i set my plugs at for better milage

[thirdstreettito]

3oz of 1:1 mix of acetone and xylene. It increases our mileage by about 35%. 3oz per 15gal of fuel(diesel or gas).

[3r!c84]

leave the windows down and no ac

[big10ratrod77]

"3oz of 1:1 mix of acetone and xylene. It increases our mileage by about 35%. 3oz per 15gal of fuel(diesel or gas)."

where can i find this stuff?

yall think ams oil in the tranny and rear end would help it helped my dads s 10 some.

ok so i read up in my chilton book i got at the shop and i found somthing interesting in 1977 the heavy duty califionia 350 used a .065 gap insted of the regular .045 gap, refering to the spark plug so i might try like .055 first and see how it dose

"leave the windows down and no ac "
i would die if i left the windows up i aint got a/c or power steering

[TwoFiftyShifter]

Gearing would help the most. So would an overdrive tranny..... Drive easy and smooth and keep it under 55 and you will get decent mileage...... 1:1 on the 465 isn't doing you any favors.

[big10ratrod77]

my buddy droped an s-10 5 speed in his 76 gmc but dad wants to keep the truck orignal. but i can still use the old georgia overdrive its that n in the shift patern

[71swb4x4]

You are spending a lot of money on things that will increase your gas mileage, but not by much. I have a feeling that if you do the math you are spending more money on trying to get better mileage than you will save by getting better mileage.

The heavy hitter will be your gearing. Your 3.73's are the weakest link. Either change them out, or use them to your advantage by installing an overdrive transmission.

[larrystone]

Many 1985 thru 1987 models came with 2.73 gear sets and there should be an entire rear end with 2.73's in a salvage yard near you.

[3r!c84]

my 84 came with a 2.73
but now has a 3.42

[glock35ipsc]

Originally Posted by 71swb4x4

You are spending a lot of money on things that will increase your gas mileage, but not by much. I have a feeling that if you do the math you are spending more money on trying to get better mileage than you will save by getting better mileage.

The heavy hitter will be your gearing. Your 3.73's are the weakest link. Either change them out, or use them to your advantage by installing an overdrive transmission.

^^ I agree.

Personally, I would do away with the open element air cleaner, that's probably going to hurt your mileage. The goal is to give the engine cool air, not hot air. With the open element breather, you are now sucking hot air from 360*. Put the OEM breather back on and duct it to the radiator support.

The 1.6 roller rockers aren't going to do you any good in this case. And it would take forever to recover the money spent on them in fuel mileage gains (slim to none at best).

Underdrive pulleys.... maybe, but again, more money spent than gained in mileage.

Send the flex fan back, that's junk. Get a pair of junk yard electric fans, you'll be miles and dollars ahead.

Everything pig rig said.

Swapping rear ends for a junk yard rear end with a better gear ratio (2.73 or 3.08) would be the best money spent. If you can't do that, taller tires would be next in line.

[tomtuna1978]

id do the 1.6rr and wile i was in there id put some behive valve springs in it, then id consider a holly pro jaction or a throttle body fuel injection from a newer truck. then id also to atleast a 700r4 od trans or a 5 speed od manule. and id tune tune tune it till it was running as good as it can ! just my 2 cents

[TwoFiftyShifter]

Honestly without changing something in the driveline I.E transmission or gears, you will spend money and not recieve much benefits. Bottom Line. I might want my truck to get good mileage at some point, and I know when I do that, I'll just get 3.08 rear gears. Plain simple and effective.

[texasfunk]

Originally Posted by 3r!c84

leave the windows down and no ac

actually, on the highway a/c would be better than windows down

Originally Posted by big10ratrod77

changing the gears is out of the question but the 3.73 i got aint as bad as 4.10s

also the reason im doing this is couse for fourth block at skool im takeing automecanics and its bout 40 miles round trip all on the highway and its a year long corse so 40 miles X 180 days = 7200 milesfor the skool year not includeing going to work and other places and just going to skool

and i orderd a flex fan also from summit

i need to give it a tune up is what should i set my plugs at for better milage

i think the flex fan wont help, i've heard it creates more drag, but i am not 100% sure on this,

[Prong]

Originally Posted by texasfunk

actually, on the highway a/c would be better than windows down



i think the flex fan wont help, i've heard it creates more drag, but i am not 100% sure on this,

Not to mention eventually putting a hole in the hood or loss of a finger when you hit it doing underhood work...

[3r!c84]

yea but with the aerodynamics of these box trucks, the windows down,i think will be better then runnin that ac compressor ?


i know on newer cars its different ive seen mithbusters

[big10ratrod77]

well im giong to talk to dad and see if we can find and hewould let me install a t5
and i got what i consider prity tall tires they ar 235/70/r15s i dont want to kill my torque mutilplication though

[tecky11]

y not drop the 15's and put on 16's, and use the same size tire

[D13]

If you look at it you will never recover the money you spend for gas mileage improvment, unless you plan on keeping the truck for another 25000 mile minimum.

Having said that:
1. Swap in a 700R4. Cheap, plentiful, all parts are available. About $350 total for the swap, gains about 20% fuel economy improvement. Or use an A-833 out of 84-87, gets the OD but still manual. 5 speed boxes are nice but still pricey and don't get you much better ratios. Target is about 2000 RPM at 70 MPH, will be 1600RPM at 55, just about perfect (just getting into the torque curve for maximum grunt at minimum fuel).
2. Swap the entire rear end for one with a 3.08 ratio. About $250 including fluids.
3. Electric fans (throw the flex fan away). $50 at a j-yard near you.
4. Close up the air cleaner and add sume ducting to the radiator opening (dryer duct, duct tape, hose clamp) $15
California plugs were gapped for emissions. Leave yours at the correct gap, maybe.05 more.
Lean out the carb just a little.
Windows up is better once over 45MPH.

Georgia overdrive is great, I use it on my DD, adds a lot, particularly if you have a lot of stop signs.
Tire inflation and put the tallest tires you can on next time you need new. Michelin radials preferred (yes it makes a difference!).

Now when I build my fuell economy special I'm starting out with an L6, converting it to TBI, then an A-833 or 700R4 with manual lock up control, 3.08 gears (overdrive and 2.52's suck. trust me). P235-78-r15's or 80 series if I can find them. AC for highway, manual windows and locks (less mass) and a tonneau (made 1.5mph improvement on my '90.).
But that's just cause I was modding the truck anyway.

[andrewmp6]

Yeah windows down gives you more drag then the ac does.If you have cruise control use it.It will save you gas but you'll get bored fast.If you want to spend money buy a good radio and speakers for it.

[big10ratrod77]

what about removing the tail gate

[bigblock73]

Tailgate removal has been proven not to affect mileage.

Just put in a new gear set, or get an OD transmission...or both! Everything else pretty much will be a waste of time/money...or will take you forever to see the rewards. Sure, small things will help...but the gears and trans will see immediate improvement.

Listen to the experts and advice.

[glock35ipsc]

Originally Posted by bigblock73

Tailgate removal has been proven not to affect mileage.

Just put in a new gear set, or get an OD transmission...or both! Everything else pretty much will be a waste of time/money...or will take you forever to see the rewards. Sure, small things will help...but the gears and trans will see immediate improvement.

Listen to the experts and advice.

^^ What he said!