Old School 427hd In 1993 K3500 Dually

[rickpilgrim]

After a few 6.5TD replacements, a 6mpg 511cid built Caddy and a piston scuffing 400sb, we are going to try the old 71 427 tall block that was in a C70 tandem dump truck I got for cheap.The 427 was rebuilt in 2008 and in 2009 owner had heart failure, no more driving and it sat untill 2 weeks ago when I bought it for $100, rust, rust and more rust.

 

The 427 needs a good tune up and I will replace alot of gaskets just because, the carb will be 650 Holley with tps(1993 has 4l80E) and shorty headers for a 454 1993 truck(due to fitment issues) and a 1978 366 HEI with the hookups for the Optishift, but here's the question-

 

Do I stop there?????????? I have never ran a 427 powered HD truck before this, The Caddy really set the bar for Duramax killing torque but 191 miles from full tank to empty really hurt. I really want durability with power and some (10-12mpg) from this. Any suggestions anyone?

[markw8]

I would think the first thing would be install it and drive it. See what you have. It won't be a high reving horsepower motor, ever. It was for torque. Remember that gas mileage wasn't much of a factor when they built it.

 

Mark

[blacksierra01]

I dont think there is much you can do for mileage, the Gm farm truck we had with the 427 in it never got more than 7 or 8 mpgs, and compared to a diesel, it was a dog. Good luck with the build though

[rickpilgrim]

I would think the first thing would be install it and drive it. See what you have. It won't be a high reving horsepower motor, ever. It was for torque. Remember that gas mileage wasn't much of a factor when they built it.

 

Mark

 

I know what you mean about torque-It was dropped off by a wreeker towing it backwords, as they said the center axle brakes were locked up. Ran a file through the points, hooked our boat gas tank to the fuel pump, dropped a battery in and started it.

When I leaned over to pick up my phone I hit/bumped the shift into reverse a at 800rpm and there it sat, all 4 wheels on the back axle spinning on the cement, center axle dragging along and that takes torque. That Caddy only revved to 4500 (shift point) or 5000 rpm ( computor overide) and everyone loved it except the fuel headache. What good is 660 ft/pds if you need oil field stock to afford it! I gues we will try it stock and see what it is.

As far as MPG goes, the 1993 dually is alot more aero than the C70 and 4.11 gears with 4l80E equals 2200-2500 rpm at 65mph so at least I can hope for more than 7-8 mpg!