Im not sure what i am getting at the moment but I need better! I know that having a 454 you're not going to get great fuel mileage but i need help maximizing what i have. Its a 1990 3500 with the 454 3 speed. The truck has 235 85 16s on the rear and the front has 265s.. like that when i bought it.. is this draining my fuel mileage and should i put 265s on the rear? Also would a throttle body spacer do much for me in this area?

 

Nahhh, the tires aren't so much the issue. About the best thing you can do is make sure you keep ut running well, tune ups, regular maintenance and such. You could change out the rear end ratio to give you a bit better mileage but it won't be stellar.

 

Stay away from the TB spacers they are a waist of money. Like already mentioned, put the money in making the truck as well tuned as possible. There really isn't anything beyond that that is going to make a 454 get good mileage and a 3 speed isn't helping either. Driving habits can help a little too.
Make sure your injectors are spraying a nice clean conical pattern. If they are sputtering it will affect mileage.

 

just another question but if i took my dual tires off each side would a regular rim bolt up just fine? Might be a dumb question but im new. If so i was going to put some sort of wheel spacer in there to make it look right

 

Going to a phantom dually setup. If you check with your local tire shop, they can make sure you get the proper backspacing. It will give you less of a contact patch, but will also efdect payload capacity and not really boost your fuel economy.

 

Please don't pull one wheel and ride around like that. It not only looks ridiculous, but won't help your gas mileage at all. Unless you going with the one real wide "Phantom" look that fills the dually fenders up.

 

Mr. Dholtham... about your mileage. I've posted this little bit of infor a couple of times in other threads, but have your mechanic check your distributor shaft's bearings. Mine were totally shot at about 120K miles, and was causing the plugs to fire as much as 10 degrees off!

good luck.

 

My old 99 454 3500 dually averaged about 10-11 mpg in stock arrangement. There was little I could do to improve that, too.

 

I'll jus play devil's advocate for a moment and I'm not trying to sound like an *** so please don't take this the wrong way. It's a 454 dually, fuel economy and heavy, high torque vehicles don't exist. I'm not sure what fuel range you're looking to achieve but you're not going to get much. Aside from maybe a propane conversion or just parking it in the garage and buying a Prius, you're not going to be able to do much to really bump the numbers.

Even doing a phantom setup on the rear will honestly make it worse because you'll have a larger contact patch with more rolling resistance.