MPG Pt.1

[Stewart G Griffin]

how are you getting 15-16mpg? i wasnt able to get better that 8.5mpg with the edelbrock i had on and since i put on a Q-jet but havnt gone through a couple tanks yet to confirm my average mpg but the last tank i got only around 10mpg.

Oh, any of these 1/2 tons can get 16-ish even with a 350.   Here is how i'm "doing it:"

Tires no larger than 235/75 15's  and make sure they are aired to at least 35psi.
2.56 rear diff gear   TH-350C  with lockup converter
2WD
STOCK 305 with STOCK 2G carb.   i think the wilder the cam, the less mpg. 
HERE IS A MAJOR THING------i accelerate gently and don't drive faster than 65.  i think this is an important factor.
Sometimes i use a tonneau cover.

Have you confirmed that your odometer is reading correct?

My latest:   255.3 miles,   17.054 gallons = 14.97 mpg

$3.599 per gallon regular at mobil   $61.38 total to fillup

i was doing a lot of hauling wood w/out the tonneau cover.

i am planning on starting an mpg pt.2 a.s.a.p. that will take it to next level.

[hondarider188]

Yeah my truck is quite a bit different that yours. on mine i got 32X11.5X15 tires and filled up to 40psi. 3.73  gears in rear diff. then the sb 350 and a TH350 not sure on a lock up converter or what it is then 4wd and a quadrajet on top of engine with sp2-p intake and as far as i know engine is stock and i do try to accelerate gently and drive "softly" and i never am really on the highway very much up to even 60mph   and the odometer i believe is correct, but how do you check it? never had a tonnueau cover just a tool box. and on my last take i average 11.35mpg which is a ton better than before. and that last tank included being out on the highway at about 70mph for 40 miles round trip and trying out the secondaries on the carb a few times just for fun. so im gonna try on my current tank to take it easy as possible and get the best i can.

[Irish_Alley]

the odometer i believe is correct, but how do you check it?

you could always ask a cop to use his laser on you. but dont go by as fast as you can just what you think is the speed limit. had someone do that around here a couple years ago asked the cop to see how fast he was going the cop said yes. the guy flew by him as fast as he could in a 45mph zone. needless to say he didnt need his speedo calibrated lol
but that being said since you know your ratio and tire size you should be around 2800rpms doing 65. its a little high but its kind of right in the middle for performance and mpgs. 11 mpg aint bad for a 4x4 but i have a 350, holley 650 i think, w/ 4.10 ratio and a sm465 manual transmission so no slipping on the converter as you would with a auto. but it been a while but i think i was 9-10mpgs with 38s. now thats keeping it below 60 and easy driving

[Stewart G Griffin]

Yes, i suppose that's one way you could do it (ha-ha!).  Another way is if you have a speed sign that reads your speed and posts it up, you know the "Your speed is" type sign.   These two ways can calibrate the speedo, but do not necessarily confirm of the odometer is reading correct.

i think the new GPS units are pretty accurate as far as measuring distance so that's one way to verify your odometer.  Another way is to use the mile markers on the side of major highways.  But don't just use one or two, use a lot of them.

What i'm using is a digital speedo/tach which also has an odometer and other functions.  You may want to look into the new GPS speedometers or regular gps units.  The prices are dropping.

[Stewart G Griffin]

P.S.  A lot of smart phones apparently now have GPS capability or apps.

[Irish_Alley]

yeah stew that scares me. when i want a app that requires gps fine location i wont download it. you be surprised on how many applications are running on your phone and what they are doing. i hate having something running when it can track me or see what im doing. granted the phones can do this by default but thats not really something i can change but i can change certain apps

[hondarider188]

ok i see what you guys mean by my odometer being correct i wasnt sure at first, but i do have one of those speedometer apps on my phone and it tells me my truck speedo is pretty accurate until i hit about 45 then it is slow as im really going 50( all based off of phone app) and it only gets worse the faster i go such as 55 is 64 and 70 is about 80 so i'm not sure what that can tell you. and i always thought their was a correcter for this on the transmission to compensate for larger tires( wouldn't my tires be the cause). Irish your are correct on the rpms at 60mph. oh and i already failed at keeping this current tank as the best i can get, because i just love to run those secondaries but only did it once to get onto the highway fast so should hopefully still be better than last tank. Also for the differential gears i think that they are 3.73 but i only think that from the sticker in the glove box. Unless someone changed them than that is what they should be.

[Stewart G Griffin]

So, i take it your tires are not stock to the truck?   i can't comment on the phone apps as i haven't used one yet.  But i can say the actual standalone GPS units are pretty accurate as far as speed and distance.

[Irish_Alley]

if the rpms are close i would say you do have 3.73. i wouldnt even know where to start guessing on the tire and the speedo gear. i know they make them for different rear ratios but not sure about tires. make sure you do have the 3.73 pop the cover off, im pretty sure you do but double check. BUT lets say you do have 3.73 ratio with 32" tires at your running about 2800 at 65. you would still be running 2800 at 65 with the stock tires 29" and a 3.42 ratio. sooooooooo with that said, if you buy the gear for the th350 and 3.42 rear ratio your speedo should be right.another but im sure theres a proper way of doing this and someone will chime in cause all im doing is guessing lol

[hondarider188]

the gear you mentioned for the th350 you mean the compensator right. and I think the biggest factor I have is tuning in my carb a little better. I bought a new(remanufactured) q-jet online and they said the jets would be fairly close to the application, but may need finer tuning. so I think I need to get some new jets and go down 2 sizes from whats in their now and maybe even change the power piston. and I was also told that larger tires helps your mileage to a point until you have extremely large tires since the whole distance traveled per revolution is increased, but it may take more to set the wheels in motion.

[Irish_Alley]

right about the tires. it essentially lowers your rear ratio number wise.  like i said before your 32s and 3.73 is like running stock 29s with 3.42 ratio. about the carb i dont know what your talking about lol the gear i was talking about is in the tail shaft of the transmission. right now its set up for 29" tires and 3.73 but with your tires its like running the 29" tires and 4.10. so if you find a 4.10 set of gears/rears that would work but the cheaper way would be to find the gear in the tail shaft. never changed one or know anything about them just like doing math problems lol so my help is limited

[hondarider188]

ok i think i see what you are saying. but im still gonna try the carb out first as that is more that likely the cheapest and probably the easiest and can make huge differences. And i will be getting my new tires pretty soon sometime next month when my uncle brings them from Missouri and they are 31X10.5 and in case your wondering why i have tires in Missouri when when im clear in utah. Well the story goes, this spring i went back out to missouri (when he was out here i road back with him) and i also took my dirtbike with me since he had just had a motocross track built. so their i was in missouri helping my uncle run a car dealership when the owner came around( my uncles brother in law) and he hired my to drive some cars back from the auction in springfeild and kansas city both about 2 1/2 hours away. so i made three trips first drive was in a 1988 chevy 2500( funnest to go 75mph on freeway) then a 2007 chevy 2500 both from springfeild and then a 2004 chevy 2500 with large lift and tires from kansas city.on top of it i was helping work on cars and change tires at the dealer ship for free. and one day i saw some goodyear mt/r tires that are brand new up in the corner of the shop and asked what they wanted for them and they told me they would give them to me for $300 which was an awsome deal. so i said yes but it will be awhile until i get the extra cash. Then a couple days go by and the owner calls me up while i was still in missouri and he tells me he'll just give them to me since i had been working at the dealership anyway for free. the day soon came for me when it was time to go home and my parents had decided to put me on a plane to go home instead of driving 1000 miles to pick me up since flying was more cost effective. So now i have a brand new set of tires for my truck and my dirtbike sitting in my uncles shop rotting away in missouri until he comes back out to go camping and to see by sisters wedding next month. All of this back in missouri was clear back in the end of May and First of June when i came back. So the exact same time i was in missouri is when that terrible storm hit Oklahoma then hit the town i was in the next day, luckily though no tornado's touched down when it hit me. quite the story huh:)

[hondarider188]

sorry i feel i kinda hijacked your thread ill try to stay out of it more, i was just a little curious as to what you were doing different than me on your truck.

[Irish_Alley]

theres only one way to know what hes done compared to you

[hondarider188]

ya i guess thats true. you would have to have a bad example to show the effects and differences of a good one.