68 Chev 3/4 4x4 overdrive trans swap

[1972RedNeck]

Originally Posted by Daimler

I've been thinking, working from a cruise rpm of 3000 with the 411's and stock four speed - why not both. Use the 27% drop with the Ranger to 2190 rpm. Then pull the O.D. on the NV4500 for another 25% - dropping to 1625 rpm. Dad's V-8 Jaguar weighs 4500 lbs. With the 700R4 he is turning about 1650 RPM at 65 MPH. Although the motor is 'built' he gets 28 to 34 mpg on the hiway. If the 500 Caddy motor was mildly tweaked the truck would also have the power to push the truck at these rpm's? Basically the same power to weight ratio? All i have to do is knock off a bank.

I think it would work. You probably couldn't use it on much of an incline or headwind, but for flat cruising I bet it would make some surprising mileage numbers. Get a good low-end mileage cam and some higher compression pistons (and maybe different heads, I don't remember what year they changed chamber types) to basically build it to 1970 specs and it will work great.

And before all the naysayers won't work and the engine will be lugging to hard, I would suggest not commenting unless you have actually been around a big block Caddy hooked to a manual transmission - the low end torque they produce is nuts. These aren't at all like small blocks or even BBC's.