Ford Truck,

I am trying to do an upgrade this winter to EFI and a Paxton Supercharger on the 289 bored .30 over. The motor that I got the EFI setup from a 1990 5.0 Mustang and I am trying to figure out what needs to be changed to install the EFI on this car. I have found plenty of threads what the EFI needs but I am trying to figure out what I need to change on my existing motor.

I am trying to deal with one issue right now and that issue is with the EFI Distributor. The EFI setup requires a EFI Distributor. With the EFI Distributor I need to change the flat tappet cam/lifters/pushrods to a roller cam. I would rather not replace the cam with a new roller cam because this is going to make this change much more expensive. I found this item on ebay to put a new iron gear disty for the flat tappet cam but I would also need to change the firing order of the cam (351 firing order).

FORD 302 EFI 351 CAST IRON DISTRIBUTOR GEAR M-12390-D: eBay Motors (item 370375814405 end time Sep-01-10 12:18:17 PDT)

So give me the best of your knowledge on this one. Do I need to change the cam? If so what cam is best for this setup. I have seen lots of cam choices for roller and not sure what direction to go.

If I had my choice I would leave the existing cam and the EFI if that is possible. If not what is the budget way to get to a roller setup for the EFI disty.

Thanks,

Craig

 

In theory, the MAF EFI is going to give the engine only the fuel it needs, so I would expect that you should be able to run a flat tappet cam, with that gear change on the EFI distributor. You'll only need to change the spark plug firing order if you went with the roller cam, but you should change the order of the fuel injectors if you do not. But the stock roller cam will work a lot better than the stock flat tappet cam that came with the 289. The other thing is as flexible as the MAF EFI system is, you can not get too radical with the cam.

Since you're salvaging the EFI system from a 5.0 Mustang, why not also grab its distributor, cam, and roller lifters, pushrods as well? Unless the engine has been abused by running on no oil, most of these parts are probably still usable.

 

The '90 Mustang EFI setup uses sequential injection so there are a couple wiring changes needed to make it work with the old non-HO firing order.
1) Swap the EEC connector pins for injectors 3 & 7 with those for 5 & 4.
2) Convert it to a single O2 sensor system. To do this simply patch the sensor wire for the passenger side O2 sensor into the drivers side input and be sure not to attach a drivers side sensor. The reason for this is that the computer manages the engine as two seperate banks, but the internal programming is based on the HO firing order and since the system is actually running a non-HO firing order motor the programmed banks and actual banks are mixed up. If you were to leave the two O2 sensors connected normally the computer would chase it's tail trying to adjust fuel trims and you would end up with some cylinders rich and some lean. See the link for the EEC connector pinout and how to take the EEC connector apart to move pins.

Ford Fuel Injection Wiring Harnesses

I should add that you don't need to change the cam to use this EFI system on this motor, just change the distributor drive gear and plug it in.

 

thanks Paul for the excellent insight!

Craig