Posted by Greg Coffin [172.68.150.206] on Sunday, November 16, 2025 at 18:56:49 :
In Reply to: Repower 1/2 ton closed cab wc12 posted by DDD [104.23.245.36] on Saturday, November 15, 2025 at 07:36:55 :
Since you want to keep the original frame and axles (which I think is a good plan), and don't want to install a diesel (also a good plan) there are a couple ways you can do this.
I dropped a '71 318 in my 6x6. With the short water pump it fit pretty well between the radiator and the firewall. Your half ton cab makes it even easier, since the distributor will fit nicely in the bump-in on the firewall. It has lots of power and RPM range. Mine really wants to go once it hits 3000 rpm. If I were doing it again I'd go with fuel injection, either with a 318 Magnum engine, or with a Holly Sniper kit.
Another way to go is to put a turbo on your flathead. My son and I put a draw-through turbo on our M37 with 230 engine and 4.89 gears. The turbo makes a huge improvement. The engine puts out roughly the same power as a stock 318, and the truck is very driveable. We only run 4lbs of boost. It doesn't have the same RPM range as the 318, but I don't miss it.
Most of the noise you get in these trucks is from the transfer case and from the stock engine fan. I'd replace the NP200 with a NP205 and leave the rest as it is. A flex fan will quiet down the engine a lot.
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