Questions about a Gas to Diesel conversion for a '72

[The Youngen]

Originally Posted by 67_C-30

Did you get one off government liquidation?

Waiting for one to pop up on craigslist. Im hesitant about surplus because ive heard they cost up to 3-4k on average. Way over my budget. Ive seen a xouple on craigslist in my area for 1-2k running but rotted, which is fine by me. Plus, the surplus aparently take awhile with governemt paper work before it can actually be yours. And i have to have this project done by september.
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[Vintage Windmills]

Someday I'd like to body swap a longhorn onto a rolled or otherwise damaged regular cab dmax. They have the same wheelbase of 133" so I don't think it would be that hard. Imagine that engine performance, braking, trans, and ride quality with the longhorn body. wouldn't get much better than that for a capable hauler with a classic look. And you can actually leave the truck running while going through a drivethrough.

[The Youngen]

I was thinking about putting a t5 behind the n/a 6.2. It has a 2.94 1st and a .73 od. If my math is correct, with stock tires at 28.5 inches, .73 od, 70 mph, and 3.08 in the back it is roughly around 1800 rpm which is according to dieselplace.com the rpm/mpg sweet spot. Plus, it should actually get better off the line than the turbo 400 because of the 2.94 1st vs 2.54 with 3.08. Reason im asking for someone's thoughts was because everyone has said 3.08 and a 700r4 (.7) od, will kill mpg but thats for gas, it looks to be beautiful for diesel.
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[special-K]

I haven't checked,but I figure my '85 Jimmy 6.2/700r4 came through with 3.08s. I never drove it to check mileage before going with 3/4t 4.10 axles with 35" tires. That puts my ratio at right about 3.73,based on the stock 3/4t 235/85 tires at about 31". That stuff came from my '91 Suburban 6.3/4L80E which got 22 mpg on hiway with all that. These things have more low end torque than most give credit. 1800 rpm would be a breeze to this NA motor.

[1968CHEVYC10]

Well if you need more motivation, just took my truck on a little road trip and got 22mpg, and it even has a leaky injector.

[6lcummins]

6.2/6.5s love to toast injection pumps and lift pumps. You are money ahead in the long run to go Cummins. Here is a 72 build you could look into.

http://67-72chevytrucks.com/vboard/s...d.php?t=310493

[67_C-30]

Originally Posted by 6lcummins

6.2/6.5s love to toast injection pumps and lift pumps. You are money ahead in the long run to go Cummins. Here is a 72 build you could look into.

http://67-72chevytrucks.com/vboard/s...d.php?t=310493

The only ones that have IP trouble are the 94 - 99 6.5's with DS4 computer controlled IP's. The have a drive by wire system and the throttle is controlled by a pump mounted driver (PMD). They are troublesome, but all the 6.2's and early 6.5's mechanical IP's and are stone reliable. Cummins are great, but are no means a drop in these trucks. They need either a body lift or firewall modification to fit in a 2WD and they put a lot addition weight on 1/2 ton ball joints, wheel bearings, etc. The low RPM capability of the Cummins is going to require an OD transmission to run highway speeds as well. If you building a truck strictly for mileage, you'll never offset the cost of going with a Cummins over the 6.2, unless you already had the Cummins.