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67ChevyRedneck · 11-26-2004, 01:14 PM

I've always had gear questions too and no one has ever really been able to answer them. My truck is a '67 Chevy with a 350 mated to a 700R4 which spins a 3.73 rear. The carb is an edelbrock 650. My truck gets 15.5 mpg on the highway going about 75mph. At about 65 the tach reads 2000 and at about 75 it reads between 2300 and 2400. I have recently converted my truck to power disk brakes off a 71 GMC...and yes, GMC did put coil suspensions on trucks, which gave me awesome braking power and gave me the 5 lug pattern. Out back, she still has 6 lugs. I have access to a 5 lug 3.07 and a 5 lug 3.73. I think the 3.07 would be too high for the 700R4 but I would like to improve my mpg, her "around town" average is only around 13. The only other route would be to spend some big bucks on something in the 3.40's...is this even worth it? Is 15mpg the best these can do? I've seen a couple of magazine articles where these trucks could get 18 highway...are these people liars?? I like the way the 3.73 and the low first and second gears of the 700R4 combine to kick ass at stoplights!

Should I just swap my 3.73 for another 3.73? I need to convert to a 5 lug rear anyway. Also, I DID NOT "hit" the gas at all on the tanks I was trying to figure out my mpg's.

11-26-2004, 01:14 PM	#35
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	I've always had gear questions too and no one has ever really been able to answer them. My truck is a '67 Chevy with a 350 mated to a 700R4 which spins a 3.73 rear. The carb is an edelbrock 650. My truck gets 15.5 mpg on the highway going about 75mph. At about 65 the tach reads 2000 and at about 75 it reads between 2300 and 2400. I have recently converted my truck to power disk brakes off a 71 GMC...and yes, GMC did put coil suspensions on trucks, which gave me awesome braking power and gave me the 5 lug pattern. Out back, she still has 6 lugs. I have access to a 5 lug 3.07 and a 5 lug 3.73. I think the 3.07 would be too high for the 700R4 but I would like to improve my mpg, her "around town" average is only around 13. The only other route would be to spend some big bucks on something in the 3.40's...is this even worth it? Is 15mpg the best these can do? I've seen a couple of magazine articles where these trucks could get 18 highway...are these people liars?? I like the way the 3.73 and the low first and second gears of the 700R4 combine to kick ass at stoplights! Should I just swap my 3.73 for another 3.73? I need to convert to a 5 lug rear anyway. Also, I DID NOT "hit" the gas at all on the tanks I was trying to figure out my mpg's.