69 350 Fuel MPG

[Erv M.]

I am planning to drive my car from Southern California to the Texas Regional. I am planning my driving legs and hotels and need some help on mpg to be expected.

It is a base engine with 3:08 rearend. I have never paid any attention to mpg but now it becomes important; running out of gas is no fun.

As a barommeter what should I be using for mpg?

[Duke W.]

Re: 69 350 Fuel MPG

Figure 18 MPG and 15 gallons available fuel with the rest "reserve" - about 270 miles or about four hours driving at about 70 MPH average.

If the fuel gage and odometers work, record fuel added at each fill-up along with the odometer reading so you can compute actual fuel consumption.

And if you reset the trip odo at every fillup, you have a cross reference against the fuel gage.

Once you have some good data you may find that a full fuel tank will give you at least five hours driving endurance (about 350 miles) with a reasonable reserve. That's about as much as my bladder can handle.

I can't remember how low I ever let my tank get, but given its shape at least 18 and maybe as much at 19+ of the 20 gallon capacity should be useable.

I10 in Arizona has mile markers (some might be missing), so it's a good opportunity to check the speedo and odo for accuracy. If you use a stop watch to time yourself between mile marks, your speed is 3600/seconds between markers. On cruise control cars you can do a ten mile checks and get a very accurate results.

I usually use 10 and 100 mile legs to check the odometer.

I haven't driven from CA to Texas for twenty years, but I make an LA-Scottdale trip once in a while. I usually fillup near Palm Springs, which gets me non-stop to Scottsdale. (Fuel is expensive in Blythe.) On the return trip I add about three gallons near Palm Springs to get home. (Fuel is usually cheaper near home.) The cars I use on this trip have about five hours/350 miles endurance. The door-to-door trip is a little over 350 miles so prudence dictates one fuel stop and so does my bladder.

Duke

[Jim T.]

Re: 69 350 Fuel MPG

I made the trip in my 1970 350/300 with turbo 400 and 3:08 from San Diego to Dallas in 1975. Two people and luggage in the car and one large Samsonite on the luggage rack.
Used the air conditioner for the June trip.
I have always remembered the best MPG I got was 22 on two tanks, actually the best highway mileage I have ever got was on that trip. One thing about filling up a 1970 you could see how full you filled the tank to assist in accurate MPG useage.
I had installed a Holley 650 6210 spreadbore a year earlier and was very pleased with the mileage.
Also run full time vacuum to the distributor.
Don't know if they contributed to MPG, but also had 69's optional side exhaust system.
I had the timing at 10 degrees and Champion J12 plugs.

[Joe L.]

Re: 69 350 Fuel MPG

I am planning to drive my car from Southern California to the Texas Regional. I am planning my driving legs and hotels and need some help on mpg to be expected.

It is a base engine with 3:08 rearend. I have never paid any attention to mpg but now it becomes important; running out of gas is no fun.

As a barommeter what should I be using for mpg?

Erv-----


In 200,000 miles of driving my 1969 equipped with 300/350, M-20, and 3.36:1 rear gear ratio, I got 13 to 20 MPG. On a highway cruise, my mileage would usually be in the 18-20 MPG range.