Hey Guys!
I don't post in here a lot, but my current project is swapping the engine in my '94 F-350. So to keep all the questions I am going to have organized, I will post them all in here.
I'm going to replace the current EFI engine with a stock '86 351W (carb'ed). No emissions to worry about here, so no worries in that respect.

First question:
Headers. Changing the stock manifolds means having to deal with closing all the exhaust ports in the manifolds. Thought it might be better to just drop in headers while the engine is out. I could use a new exhaust system anyways! recommendations on sourcing and maker? I have hedman headers on my CJ, they seem to work all right. I have a good set of mufflers to throw on it already.

Second question:
The fuel system. This is set up as a dual tank, hi pressure system. I need to drop the pressure and connect it to the new engine. Any good ideas? I know it will involve either a regulator to drop the pressure, or maybe bypassing the in-tank pumps and just running the lines to the engine-mounted fuel pump. Will the transfer switch still work this way? What do you use to adapt the lines over?
If I really had to I could drop the aft tank off the truck, but its nice having that extra fuel on board. But losing it would make room for the hydraulic wheel lift mount I have sitting here...

Third question:
I have the entire ignition system for the carb'ed engine. Would it be better to get a replacement engine harness and splice into the truck with it, or just re-wire the truck to work with the new engine? I don't really want to cut up the harness I have now, I may find a use for the old engine later (after it gets rebuilt).

I'm sure I will have more questions later, but this is a good start! Thanks for any and all help with this project!

 

This comes up a lot and we usually start out asking the big question.. why do you want to do this? Overall this is big step backwords in every way, less power, worse drivability, and a ton of work to accomplish that. If the existing motor is shot then why not rebuild it or at least bring the '85 up to the newer spec with modern heads and cam, swap over the EFI intake and drop it in.

 

probably because I have been fighting the EFI crap on this truck for over a year, every since I bought it in fact. I rebuilt the engine, including replacing the heads with a supposedly rebuild set of heads when I found a crack in one of the stockers. Didn't get 1000 miles on it before the "rebuilt" heads dropped 2 valve seats. Replaced the heads again...now it won't get any spark for anyone who has looked at it. Spent over $300 on parts trying to get it to start and run correct.
My shop neighbor is a very good mechanic but busy as hell, After looking it over, He suggested that I replace the troublesome engine, so I bought a good runner for a cheap price (trade).
I have to get this truck running. Even if I put the EFI back on this engine, there is the No Spark problem no one can track down. I want it simple, power output I don't care about. As long as I can pull the trailers around I'm happy.

In the year I've owned this truck, I don't have 1500 miles on it total. This is the 3rd time I've had the engine out, and it will be the last.

 

OK I feel your pain, it's no fun trying to track down problems like this. Did you open a thread here asking about your no-spark problem? I don't remember seeing it and my first suggestion would have been to replace the distributor since that's where the spark signal originates, was that one of the parts you replaced?

 

Nope I didn't. It went to the shop 4 months ago, but the deal I made to get the work done meant the truck got put on his back burner every time. Granted, my mechanic has been busy as hell for a 1 man shop, so I don't blame him. Having to barter parts for work is low priority.
Either way, The EFI is already sitting on the shop floor, the carb'ed engine is hanging from the hoist, so lets deal with that, can we?

 

You need..
Carb and intake.
Duraspark distributor and ignition box
A bypass fuel pressure regulator to drop it down to 5-6psi, this will allow you to retain both tanks.
Then disconnect the main engine harness in the truck and put it aside, and hard wire the fuel pump relay to turn on when the key hits run by grounding the fuel pump pin in the EEC test connector(see pic below). You can then remove the EFI computer so you don't have to look at a check engine light all the time.

 

Ah! there we go! Thats the info I needed. Thank you very much, I have everything but the bypass regulator. Headed off to find that now! Thanks again!