so here's the thing i m in the 1st stages of a big rebuild body off and have got to the point where i have to make up my mind with what to do with my engine, i have a 5.0l efi sitting on the floor in the garage and thinking that it is the best place for it. i want to upgade to the 351 but not sure if the computer works with mine . i would like to go carb but i have been reading some post and m not to sure now so was wonding if anyone had any ideas for me that would make my job an easier .

 

Keep what you have unless you feel like tracking down a computer for a 351. If your truck has an E4OD then you need a computer for a 351 WITH an E4OD. The E4OD needs the computer to make it run properly.

Going backwards (from EFI to carb.) is just silly in my humble opinion. Why go back to a system that needs constant tweaking and tuning and has NO means of giving you any indication of what is wrong when something does fail. The simplest thing to do is put back what you had before. The swap to the 351 would not be much more difficult. (Again, the computer is the biggest issue). Kemichalburns did this swap a few years back and he knows a lot of the in's and outs of the project.

 

The 1991 model year would be the last year you could revert to the carb on easily and not loose alot of the functionality on the truck, unless you have an E4OD, then you should just retain the EFI. The EFI is probably the best system if you will do alot of elevation changes, temp variations, forced induction, or other constantly changing driving conditions and modifications. The some of the biggest hang ups in the Speed density system is that it is not well suited to large airflow change, unlike Mass Air, and that the truck exhaust doesn't flow quite so well from the factory. Personally, I rather have fuel injection over Carburation but I dont mind tinkering with Carburation either, so i would just stick with the fuel system that the vehicle came from the factory with just to ease frankentruck problems.

The 351W will use most all the same wiring harnesses as the 302EFI but the comp should be up changed to a 351W computer to compensate for the airflow change that the 351 has compared to the 302. The 302 computer can only handle a displacement change of around 15% or a 347 ci engine so it would not work very well for a 351. The computers available are for electronically controlled transmissions and non-electronically controlled trans.

It really depends on if you want the upgrade bad enough and how much money you are willing to pay to do the upgrades. Look and Fordfuelinjection.com as that resource will give you alot to look at for the fuel injection system and I thought it was really educational on the ford fuel injection system, even if it is geared towards the 5.0 efi in an EB.