mine is a 94 where you can turn the overdrive on or off on the column, but the overdrive is always on right?....unless i press the button to turn it off?....and what is the overdrive used for anyway, i am not educated at all when it comes to overdrive, ive been told if i turn it off i will get a little more get up and go, but i guess turning it off also isnt helping me on the gas issue either then huh?

 

Ok, Here it goes. You need to install 3.73 gears in the rear end of your truck to see the same type of torque, acceleration and gas mileage you had with the smaller 28" or 29" tires that were on her stock. Also, if your truck is a 4x4 you HAVE TO INSTALL a MATCHING new front 3.73 ring and pinion as well. This is important so you don't grenade your T-case/differentials/transmission etc. You can go to www.ringpinion.com and you should have an 8.8" ring gear As far as the speedometer variation goes: Wheel speed from 235/75/R15 (stock tires) to 33" tires. Speeds are in MPH.
30=34 55=63
45=51 65=74
50=57 70=80
I hope this helps.

 

Holy crap RotGrubestier, those speed differences are huge.

I can see how going from 29" to 33" tires can hugely affect your fuel mileage calculations, but if you knew these ratios and the math, you could adjust our fuel mileage calculations to compensate for the bad data.

You said your getting 10mpg, so say you were calculating 150 miles on 15 gallons.

33
-- * 150 = 170.69
29

So you're actually get 170.69 on those 15 gallons. Thus your fuel mileage should be: 11.38mpg

 

thats perfect thats exactly what i had 150 with 15 gallons thanks alot that helps me so much

 

I have 3.08s and 31" BFGs in a 4x4.
Torque is not how i describe the take off. Everytime I read about the 300 being a great torque engine. I lift my hood to see what I have then.

 

hey josh, i have an idea that may help you out a bit. either remove the hollowed out cat completely or replace it with a high flow cat that has a port for your o2. ive seen bad things when it comes to gas mileage and hollowed out cats. also, its cheap and fairly easy to replace those o2 sensors. that can help a smidgit with the gas mileage (make sure you do not have the check engine light on). ummm clean air filter as always...and when regular driving, try to keep the rpms under 2k and that will help...though i know its hard to drive easy in a truck with good exhaust. hope these ideas help your mileage a bit more.

chris

 

I know everybody is talking gear ratios etc, but how about checking for vacuum leaks and a good tuneup? First things first.

 

well where would i start on checking for the vaccum leaks?.....and what would i be looking for and how would i do this?....a detailed description would help alot thanks!!!....i did take off my smog pump and i know the vacuum hose going to that is just sittin there wide open, how would i block this?

 

thanks chris, so with the cat hollowed out its messing with my o2 sensor?...it it really that bad of something?.....i dont understand, sorry im just now starting to do work myself on my truck and still learning thanks alot

 

the cat hollowed out is not necessarily messin up your o2 sensor. the hollowed out cat MAY be giving you crappy back pressure. i had a friend who hollowed out the cat on his camero. as soon as he did this, he lost a lot of gas mileage. that though was on a single cat setup. i am not positive if this will happen to the crazy dual cat setup. if the second cat doesn't have an o2 sensor in it and i am pretty sure it doesn't, you could cut it off and just put pipe in the place of it. if it does have an o2 sensor, you could replace it with a highflow cat with a spot for the 02. if you have check engine light on, it may be caused by the 02 sensors. if you take care of the cat's, this may help fix the problem (you could run a test on it and pull the codes to see if it is before you spend money). what i was saying earlie was that ive heard (i haven't yet done it but plan to) is whether or not your o2 sensors are bad, it is a good idea to replace them after so many years because they are cheap. if the o2 sensors are clean and reading correctly, your fual/air mixture will be more even saving you gas. if they are bad or your light is on, the system defaults to a certain amount of fuel mixture, which can waste gas.

when it comes to doing the work yourself, as long as you have an idea of what you are doing, i say go for it. i am basically in your shoes. i had this ole truck sitting at my house not used because of a head gasket leak. with no knowledge at all, i ripped it down, realized it was too far beyond repair, and went and got a referbished engine and am in the process of an engine swap, learning as i go.
good luck
chris

 

Josh you can use almost anything to plug a hose. A vacuum hose doesn't need a clamp if the plug fits tightly. I've seen golf tees, dowels, bolts, corks and commercially made plugs and caps. They all work.

Once you have plugged up any obvious sources, use a can of carb cleaner with a tube and spray in onto all manifold mating surfaces, fittings etc. Any change in engine rpm indicates a leak that needs repair. Be aware that this stuff is pretty flamable so use common sense.

 

i had 33's on my truck a while back before i went to 35s, i figured out that when i was going 60km on the spedometre, im acuaully goin 80km, 40 is acually 60, 20 is 30 and 80 is 100.