My 305's MPGs.... :-(

[OldGray]

I have a '79 Bonanza Longbed w/a 305.  Just put new cap, rotor, plugs, wires.  Getting about 10.5-11.5 MPG.  Seems like it should be better...?

What is the timing setting on it?  I think we have it at 10dg BTDC.

Any suggestions for boosting mileage?  THANKS

[1967KaiserM715]

Check your air fuel mixture with a meter, a tuning shop should have a meter.

Is the mileage all city miles?


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[Stewart G Griffin]

The first thing is to determine is if we are calculating mpgs the right way.

ARe you 2wd?

[FlatBlack77]

are you running the tank down as close to empty as possible?

if you are calculating 20 gallons in a 20 gallon tank but are only using 16-18 before refilling then it will affect the calculation.

and are you filling up based on the gas gauge or how many gallons you put it?

what size tires and transmission do you have?

[OldGray]

Trans is Turbo 350.  2wd.  Tires - 255/70-15.  Driving is mixed, but a lot of highway.  I don't drive a lot of miles.  MPGs are calculated using my FILLUP app.  I do not wait until near empty be cause my gauge goes WAY past full when I fill it, and I am not yet sure where it runs out!

I don't care for the MPGs, but it may just be what it gets.  I do make up for the spending on gas though, since the parts for this truck are dirt cheap!

[FlatBlack77]

how does the app work?

[big_al273]

the most reliable way to figure out your MPG is the old fashioned way, next time you fill the truck up to full take note of your odometer reading then next time you fill the fuel take note of how many gallons you put in and the divide that number by the number of miles you've driven since the last fill up. My last tank got 96.2 miles and i put in 72 liters (19.02 Gallons) so when i divided 96.2 miles by 19.02 gallons i figured out that i got 5.05 MPG city

[OldGray]

the most reliable way to figure out your MPG is the old fashioned way, next time you fill the truck up to full take note of your odometer reading then next time you fill the fuel take note of how many gallons you put in and the divide that number by the number of miles you've driven since the last fill up. My last tank got 96.2 miles and i put in 72 liters (19.02 Gallons) so when i divided 96.2 miles by 19.02 gallons i figured out that i got 5.05 MPG city

Yep - that's exactly what the app does - only easier!   

[Irish_Alley]

whats your timing at?
do you have smog equipment?
do you keep it uner 55?
do you take off easy?

[OldGray]

whats your timing at? - 10dg BTDC
do you have smog equipment? - don't think so...?
do you keep it under 55?  - Who does?  Speed limit is 65, I do 65
do you take off easy? - somewhat, I am not a hot rodder anymore...

BTW - the tire size difference means I am actually getting around 12mpg.

[redhot1.4]

My 350 3 speed
Running 285 75 r16 is best 11.3
I thought 305 was suppose to be better in mpg wise.

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[OldGray]

I have heard from a number of people that with a TH350 that I'd be luck to get good MPGs, so probably not gonna happen I guess!

[Stewart G Griffin]

I have heard from a number of people that with a TH350 that I'd be luck to get good MPGs, so probably not gonna happen I guess!

Not sure why they'd say that----i got 18.85 mpg recently with a TH-350C.   Now, if you had a th-400..............

[redhot1.4]

I have heard from a number of people that with a TH350 that I'd be luck to get good MPGs, so probably not gonna happen I guess!

I agree. I like to have an overdrive when I sold my daily driver. My Ole 78 bonanza became my new daily driver again. So I'd like to boost those mpgs a little more

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[Flyinhillbilly]

Check your air fuel mixture with a meter, a tuning shop should have a meter.

Is the mileage all city miles?


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I tune all my stuff with the innovate MTX-L. About $175 on fleabay, and you can dial them right to the numbers for maximum gas mileage at cruise, and max power at WOT. It makes it much easier when you can see your A/F ratio as a number in real time.