EFI on a 1966 Mustang

An E303 is probably ok for you, but there's a couple of things to think about:

To convert your block for roller cam you're going to need to get either linked lifters or one of the conversion kits to mount the spider.

You could run a flat-tappet cam with the right firing order (351 pattern).

Make sure the cam gear is correct for the distributor gear you end up (roller cams require a hardened steel gear).


As far as throttle body use a stock 60mm one with your setup, should be plenty. Injectors you're probably fine with 24lb injectors (make sure you get a mass air sensor calibrated to the injectors).

You also need to start thinking about if you're going to run EGR, what year harness/computer, things like that. It's not a hard swap, but the details matter!

The stock 19lb injectors will be more than plenty, along with the stock mass air and throttle body. I would also not use your existing 5.0 intake. Just step up to a gt40 intake from an Explorer since theyre only a couple hundred bucks and will give you a good 20-30 horsepower, although the old t-bird intake will work. I had a list of websites with info on the swap, since Im interested in doing it too, but lost it when I had to reboot my computer recently.

I know that you didn't really ask, but being someone that has an injected 66, let me be a voice of reason about the swap.

It sure is nice to have it crank first time every time, especially in the winter, but there are downfalls:

1. You've got all the power now that you'll have with the EFI - i.e. the car won't be any faster.

2. With your level of mods, you'll probably need a custom tune to cure any driveability problems.

3. Swapping manifolds, rockers, heads...damn near anything is more difficult due ot the amount of FI crap on top of the engine.

4. Forget about fuel economy - this is a hotrod and you won't be able to keep your foot out of it.

Think long and hard about the decision to inject your engine. If I had to do it all over again, I probably would have chosen to keep the carb.

Specifically to your questions to have the same level of power on the engine you are going to need:

1. Edel Proformer or Proformer RPM II or Cobra intake
2. 70mm Throttle body
3. 76mm minimum mass air meter
4. 24lb injectors
5. I would get a custom ground cam, I have the e-cam and it's not that great, with your heads you need a bigger cam.

Good luck with it....

Don't forget the fuel system; the Mass Air systems used a return system, where a pressure regulator sits on the fuel rail and returns excess fuel to the tank. So, you'll have to run an extra line just for that.

You will also need to figure out how you're going to change from a low-pressure, engine mounted fuel pump to a high-pressure electric pump, either in the tank or external to it.

There are a LOT of articles out there, so I suggest you do some research and make sure you really want to do this--it can get quite expensive!

It cost me around $3500, and I already had the intake! Of course, I purchased a ready-made harness (the FRPP harness, which was $550), I purchased a new FRPP Lighting MAF and FRPP 39lb injectors (got a deal on them from E-Bay for $200 shipped), and I bought a TwEECer tuning device (another $525), plus I bought ALL NEW sensors, just so I wouldn't encounter any problems with faulty sensors along the way . . .

You could probably knock off a grand for the TwEECer and the harness (if you already have a harness), another couple hundred for the MAF and injectors (if you have them already), but you're still going to need a fuel system that is capable of supplying sufficient fuel and the proper pressure, and in such a way that going around a corner isn't going to starve it.

Here are a couple of places you could start out with to research doing this:

EFI 5.0 install

TCCN II - Tech How-To > Restomods & Upgrades

Ford Fuel Injection Magazine Articles

You will see from these articles just what exactly is involved, and it might change your mind.

I researched for a LONG time, kept accurate records of everything I purchased, and made decisions based on longevity, and that's part of what caused the large expense, but even without the extra expenditures I made, it CAN get expensive, so expect that aspect if you decide to go ahead and convert it.