Differential Calculations

[Crosley.In.AZ]

Cros and T-slick, are these mileage numbers out on the highway or around town? If I'm only running around town mileage is 12-13 as it never gets into OD.  I certainly agree about the low rpm's, I would think with a 3.08 gear you would have to be running 80 mph or better to have a non lugging condition. Just for the record I'm running a 3.42 gear in a 3700# car with a 27" tire. That's 2000 rpm at 70mph

Hence the reason I installed the EFI setup..... the low RPM I was at.

I called Howell several times for help with mileage & driveablity problems.  I ran a scanner on the truck for over a week watching readings Howell asked for. The setup would go rich for 1/4 to 1/2 mile at times, then run fine. Low speed engine response was good some days , garbage the next.

The day I called to return the EFI setup for a refund,....... suddenly it was all hands on deck at Howell. I was asked many questions.  Then ....  after I listed the dates and times of my phone calls,  they relented.

I went back to the t-350 in my truck. It may have been 3.07 gears in the truck LOL... I messed with the carbs a bit. Holley 3310 = plenty of power, no mileage... Carter = good performance, fair mileage.

[1FATGMC]

one thing to consider with an OD trans, my 48 chevy got 10 mpg with a 400 turbo and witha 700?


10mpg

engine setup has a LOT to do with everything...

It is not going to help until you get into 4th     , did you remember to shift or did you still think you had a 3 speed      

Jay I would look into the 200R4 option real serious.  It is smaller and would fit your application physically.  Look for a used one and put it in the way it is and upgrade it as time and money dictates.  Just don't get on it as hard.  I put one behind a little 305 a couple years ago that was used (from Hooley) and it has been to Mich. and Calif. and a bunch of other places with no problems.

c ya,

Sum