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tincan1966 · 08-04-2013, 02:31 PM

The setup we are running came out of a 1991 Olds Custom Cruiser wagon(full sized) 4100 lb car. It had a 700R4 trans and a 3.42 gear, got 20-22 mpg all day long. truck is similar in weight, but has 3.08 gear. 700R was bad so used the TH350C with lock up converter that I had. Final drive is not really overdrive, it merely takes out all the slip in the converter, still 1:1 final, but engine RPM drops below 2000.

I also forgot, we changed out the tires to a set of 20's w/ 245/75/R20 that are actually closer to 30" tall, so that attributes to a higher effective ration, as well.

08-04-2013, 02:31 PM	#6
tincan1966 Registered User Join Date: Oct 2010 Location: Independence,KS Posts: 1,477	Re: 20 plus mpg question The setup we are running came out of a 1991 Olds Custom Cruiser wagon(full sized) 4100 lb car. It had a 700R4 trans and a 3.42 gear, got 20-22 mpg all day long. truck is similar in weight, but has 3.08 gear. 700R was bad so used the TH350C with lock up converter that I had. Final drive is not really overdrive, it merely takes out all the slip in the converter, still 1:1 final, but engine RPM drops below 2000. I also forgot, we changed out the tires to a set of 20's w/ 245/75/R20 that are actually closer to 30" tall, so that attributes to a higher effective ration, as well.