higher gears??

[midnite]

so i have a question. on my 3/4 ton 2wd truck. i have 3.54 gears which work great for hauling/pulling hills but its killing me as far as fuel milage goes. i was wondering where would be a decent place (junk yards excluded) to find a set of higher gears. im just looking for something that will increase my fuel milage without sacrificing a whole lot on the pulling hills/hauling aspect. i know there is going to be a trade off on this but im just trying to figure out what would be the best gearing here. at 50 mph my truck runs somewhere between 2500-2700 rpm so its not really suited for long trips of extended interstate travel where the truck would see speeds of anywhere between 65 and 75 mph. i would estimate me engine to be turning upwards of 3000 rpm and i dont want to kill it and its killing me in the price of gas. currently getting around 12 mpg or so. i have a 300 6 with a 4 speed. im just trying to figure out what would be my best option here as i can live with the gas milage and can just run the truck on an as needed only basis. im just looking into some different options is all. thanks alot,bill

 

[DNFXDLI]

You already have the most ideal setup.....going to a taller gear will drop your speed and make that 300 work harder.
Best thing is to keep it in tune and if you can swing it, get headers, intake and carb.

 

[midnite]

headers i can probly swing in the near future, as for the intake and carb setup. should i go for a bigger single bbl,2bbl,or 4bbl? there are so many options that are available and id like to find something that wont break the bank as they say. i was also considering the option of dual exhaust but that will definately have to wait. was also considering a complete head rebuild as well as a nice port and polish job to help "bump" the power output without killing my milage further or my motor(has about 180k miles on it with no rebuild) seems pretty healthy but at about 3500 rpm its begging for mercy and just wont go any higher unless i put it in neutral and hammer on it then goes to about 4000 and just stays there( it ran outta gas and i put some in it and the pedal stuck to the floor when it fired) maybe my tach is off but who knows.

 

[Alvin in AZ]

What size tires you running?
235/85-16E's on 7" wide wheels?

Which 4 speed NP435 or T18 or what?

-------------------------

What about cam timing being retarded on 300i6's?
...it kinda -had- to be done to them too, didn't it? :/

Advancing the timing ~4 degrees will give you better gas mileage.
No kidding, BTDT with both a '75 360FE and a '91 351w/5.8.

Alvin in AZ

 

[79460f100]

I think your gearing is about right for what you use it for. You could try 3:50 , but i don't think you will like it. Any higher and you have pretty well ruined any hauling , in that case you may as well get a little ranger with a 4/cy engine. I say keep it the same gearing and work on other things to help out.

 

[m78]

You might look into a "Gearvender" over drive.

 

[Fellro]

The 88 has 3.08 gears, and it doesn't do any better on gas. It is a 5.8, but I have to give up overdrive often. It tows ok, but does make me shift more often (5-speed). You are at the best gears you can get for the axle. Overdrive of some sort would be the only help. If you go to higher gears, you will lose towing capability.

 

[midnite]

im not exactly sure what size tires i have on the rear i just know that they are smaller than the front and they are 8" wide and i have 16.5" wheels. currently looking into a cheap set of 31x10.50 r16.5(neighbor has them for 60 bucks) as for the tranny if i remember correctly i thought it had a np435 but when i had to adjust the clutch the drivers side of the case said warner or werner i cant remember which it was. ive never messed with timing much except to put an engine on tdc to set a distributor (my 86 bronco 2) i have "antique" plates on my truck so towing is pretty much outta the question but if it came down to it i would. and the most hauling the truck would see is if i had to move or haul trash to the dump or something of that nature but other than that i just run it to and from work a couple days a week but i would like to be able to take say a 3 hr day trip with it should i desire to do so and not have to spend $80 or more in gas.

 

[jebadiah04]

You have the same set up as me i think. 300/t18/208. Mine gets good mileage it just needs a lil work before i can cruise it to work (and plates)

Sent from my mudwhistle via lemmiwinks.

 

[jebadiah04]

i would estimate mine near 20mpg last time i drove it. On stock sized tires, which are like 28"s or something

Sent from my mudwhistle via lemmiwinks.

 

[Turtle400]

I use to own a 85 F150 4x4, 300 with the T18 4 speed with 3.08 gear

I found the best setup for what i had was 31 inch tall tires and just free the exhaust up with the newer split manifold. My Rpm at 70 mph was 2700 and only got 17 mpg with the 1bbl carb

 

[midnite]

my truck has 3.54 gears in the rear so im pushing close to 2500 or so at about 50-55 mph

 

[dustybumpers]

Swap the 4 speed out for a 5 speed.

 

[Alvin in AZ]

im not exactly sure what size tires i have on the rear i just know that they
are smaller than the front and they are 8" wide and i have 16.5" wheels.
currently looking into a cheap set of 31x10.50 r16.5(neighbor has them for
60 bucks)...

If you're gonna run 16.5's then it's good to have extra wheels! LOL

Don't have to be going very fast and get a flat with them sorry "sixteen-
fives" and the wheel gets ruined. :/ Many times had to walk back up the
road to pickup the flat tire. LOL Or even more fun getting the 16.5 tire
unwrapped from the axle. LOL

That's what was coming on the company trucks in the 70's and in ~2+
years we'd turn the truck in for a new one and typically only have one
original wheel with it. And it may have only survived because it'd spent
most of its time as a spare. LOL

Many of us carried two or three spares.

...thought it had a np435 but when i had to adjust the clutch the drivers
side of the case said warner or werner i cant remember which it was.

LOL

...would like to be able to take say a 3 hr day trip with it should i desire to
do so and not have to spend $80 or more in gas.

Where you at (elevation)?

Is the tail pipe really sooty?
Touch it with your finger, how much black rubs off?

I was asking others about the -cam- timing on 300i6's. But yeah, check
the ignition timing with a light at idle and then rev it up and see where it
goes and if you can get to advance in little steps.

A lot of guys that are into 300i6's really like that 1Y Rochester.
Never messed with one myself.

Alvin in AZ

 

[DNFXDLI]

I use to own a 85 F150 4x4, 300 with the T18 4 speed with 3.08 gear

I found the best setup for what i had was 31 inch tall tires and just free the exhaust up with the newer split manifold. My Rpm at 70 mph was 2700 and only got 17 mpg with the 1bbl carb

my truck has 3.54 gears in the rear so im pushing close to 2500 or so at about 50-55 mph

Use this to run your numbers...

http://www.csgnetwork.com/multirpmcalc.html

Turtle....you would be closer to 2350 with that combo.

 

[midnite]

i live in western md. if theres anyone from the area on here they will tell you we are surrounded by mountains here. i expect my fuel milage to drop due to the hills. as for the tail pipe well ill put it this way. after i "washed" the carb my truck started running like crap. i found out that my choke wasnt working properly so i installed a hand choke. when my choke failed it would blow black smoke when warm and run like crap but when cold i had no problems.(thus leading to check the choke) after i installed the hand choke i havent seen any black smoke and since it blew it before i installed the hand choke checking for it now i would think is pointless since i know that there is soot or atleast traces of it in the exhaust system

 

[m78]

Nice link Duncan. Thanks.

 

[Turtle400]

Use this to run your numbers...

http://www.csgnetwork.com/multirpmcalc.html

Turtle....you would be closer to 2350 with that combo.

great link, and its ben so long since i owned that truck i may of ben wrong.

 

[Alvin in AZ]

i live in western {Maryland?}. ...we are surrounded by {hills ;} here.

Cool, found the "Cumberland Gap" that I'd always wondered about.

I always thought it was funny how Virginia was farther west than West
Virginia. LOL

"North Virginia" would've worked tho.

after i "washed" the carb my truck started running like crap.

BTDT! LOL

Actually I washed the engine like I'd done many times before but this -one-
time while pulling the plastic bag off the carburetor the plastic bag dribbled
water in the fuel bowl vent. Weird as anything how that could even happen
...it was freaky-weird. Not very much water, less than a teaspoon for sure.

The water formed a clear-gel with the gas (at that time ~'95?) and would
intermittently plug up one (or both?) of the main fuel jets. Drove me nuts.

Got a new Standard Motor Products ignition coil with threaded terminals out
of the deal tho, while fishing for a cure. Man I like that coil, got rid of that
(IMO) really icky white plastic clipped-on crap. LOL YMMV?

Stopped along side the road to check my fuel level and see if there wasn't
something in the fuel bowl, Everything was fine, -looking- ...but see? That
clear-jelly can't be seen looking down into the fuel bowl half full of gasoline.

That sent me in all the wrong directions.

Finally decided it acted like something in the carburetor's fuel bowl (BTDT
before with other vehicles, never in my '75 F150) and pulled it off, dumped
out the gas in a pan and there that crap was. Clear globs the size of and
shape of purple hull peas.

That's my story and I'm sticking to it.

Alvin in AZ
ps-
"chokes are for those that never learned how to start a vehicle without a choke" -Alvin
That's been agreed to by mechanics/carburetor guys from all over, even Canada.

...choke had been wired open for maybe 10 years and got the idea one day to
get rid of all that extraneous crap, like I meant it. Hmmm... you know... seems
like it was the same time of the "Jello in the fuel bowl" fiasco. xD

 

[DNFXDLI]

Nice link Duncan. Thanks.

Thanks Mark, I've had that one bookmarked for ages.