83 C10- 250 swap to 305

[VRod Scott]

I live in North Carolina and my Truck won't pass emission inspection. I have an 83 (2wd) short box with a 250 with an Integral head arrangment. (3 sp manual trans) The truck is in decent shape and drives very well, but I have a horrible exhuast leak at the manifold. I've tried to repair and researched the situation to find there are no longer replacment heads or any way to repair my existing head to solve the problem. All advice has been put a V-8 in it. So this is why I'm writing.

I have available a doner 78 305 complete and available to drop in. I've been told by an inpsector that the only emision equipment needed is Converter, PCV, PAC, and air canister. I've been to the local Junk yards and have found other loner parts such as Fan shrouds, Aleternator, power steering brackets, Y-pipes, frame mounts, etc. I don't find much information on the bell housing area. From all the parts books I've looked at, it seems the 11" clutch and flywheel arrangement and bell housing are the same for the 250 and 305 with manual 3 spd. Does anybody have any knowledge on this? I'm also looking for information on any other items for this swap and may need to know about. Thanks for you help.

 

[David Hall]

Your 3 speed transmission will bolt to chevy 305. Also don't forget to upgrade the radiator to handle the 305.

 

[VRod Scott]

Thanks David, when I started researching, was nervous about all the items I had to change, I've read some articles saying it drops right in, others talk about complications with motor mounts, etc. Radiator and Shroud look to be the main items. Nobody ever says much about bell housings and clutch lionkage issues. I'm sure I'll have fun adapting the wiring and vaccum lines though. This truck is so simple, it is so stripped down, doesn't even have power brakes. Power steering is the only upgade on the whole truck. Just to keep it a driver, sticking with the 305/3 speed combination, looks to make the job simple.
It's begging for a 502, can't get away with it in this state though.

 

[David Hall]

I'm sure I'll have fun adapting the wiring and vaccum lines though.

I agree with the these trucks being simple, thats why they are so popular. As far as the engine wiring, the harness will unplug from the firewall. The firewall harness is made up of 3 harnesses (headlight,engine and frame harness) clipped together and then with one screw attaches to the fuse box. Chevy made various engine harnesses (straight 6, V6, V8) most have plugs to add ac, tcc and many other options. Just find a V8 engine harness thats not cut up and add or remove what you need. To make things easier, mark items with tape when you remove them.