18.4 mpg!!!

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clhyer

clhyer

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Good morning folks,
In July I made a 4,000 mile trip and averaged between 17-17.5 for the trip. This weekend we took the Duster to Statesboro for a birthday party. Drove down on the interstate doing 70-75 the whole way (about 150 miles) and averaged 16 mpg. On the way home yesterday we came the back roads and kept the speed between 50-55 and averaged 18.4 mpg! No a/c either way.
C

'72 Duster, 318 w/A998-999 auto, 2.90 suregrip
 
That's purdy dang good Calvin.
 
That's good mileage especially @ 70. What kind of rpm are you running at 55 and 70?
 
I put a 8 1/4 under the Valiant the other day and it had 2.45 written on the rear cover. Can't wait to take it on a road trip. It will have a mild 318 and 904 combo. Should be interesting, if I can ever get it up to speed.
 
B-onefan said:
I put a 8 1/4 under the Valiant the other day and it had 2.45 written on the rear cover. Can't wait to take it on a road trip. It will have a mild 318 and 904 combo. Should be interesting, if I can ever get it up to speed.
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There is such a thing as not enough gear....
 
tmm - rpm's at 70 is 2500; I don't recall what it turns at 55...
Del- 318 w 1406 Eddy; A998/999 auto, 2.90 sure grip rear, 215/65/15 skins
Rob- we need to get together sometime soon!
C
 
inkjunkie said:
There is such a thing as not enough gear....
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I know. I just laughed when I saw that on the cover. I have a few more, one with 3.21, one with 3.55 and one with 2.74. I also have a few gear sets I could install. I have run a 2.94 before with the same combo in a 8 3/4. With the 2.94 I ran the car out past the 120mph and the speedo started back around to bouncing between the 20-30 mph mark. Only once, then common sense kicked in.:banghead:
 
I had a 76 Charger with a 318 2 bbl and dual exhaust, i had 245/60/15 on the front and 255/60/16 on the rear, dropped the nose for a nice rake, and pulled off 25 MPG. No idea what the rear ratio would of been.
 
thats awesome!!! i took an all-nighter road trip, 550 miles, when i had my 7.25 sure grip with 2.94's and 185-35-13's and got 18.4 as well. recently, after my suspension swap, with an 8.25 with 3.55's and 225-60-r15's i pulled 20.3 on a 600 mile round trip. both times were doing around 60 mph. i run a 318 highway patrol engine (87 vintage) topped with a 650 spread bore holley, backed with a lockup TF999.
 
I pulled a 8 1/4 out of a junk yard with the 245 gear and put it in my 360 duster and rolled back and forth to work 36 mi. each way on the highway and it was great. Car ran fine. I was not racing it.
 
i found with 3.91 gears and 215/70/15 rear tires, speed really matters. On a long road trip I started off going 60--62 mph and thought at first the gas gauge was stuck. Normally I would go 75 mph plus on the freeway but since it was a long trip and I tend to drive faster the longer I drive, I just babied it all the way.

I tend to get 10-12 mpg running around town, thats pretty good compared to BB's with 3.91 gears.

If I could go a steady 55 mph, it get 15 mpg or better but i can't drive 55
 
66durgederp said:
thats awesome!!! i took an all-nighter road trip, 550 miles, when i had my 7.25 sure grip with 2.94's and 185-35-13's and got 18.4 as well. recently, after my suspension swap, with an 8.25 with 3.55's and 225-60-r15's i pulled 20.3 on a 600 mile round trip. both times were doing around 60 mph. i run a 318 highway patrol engine (87 vintage) topped with a 650 spread bore holley, backed with a lockup TF999.
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I'm putting a lockup out of a 84 5th Avenue into my 65 with 2.94 gears. It will be a 273 with domed pistons (9.6-1 measured CR), Isky E-4 cam, 500 CFM AFB. I hope I can break into the 20 mpg club with you.
 
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