Truck is running rough. Mechanically all is correct. Have a 1993 F-150 w/302 that I have replace with 351W. Used my 302 heads that are ported and larger valves with a mild Comp.Cam. So yes, its a 351 with a 302 firing order.

My question now is; can it be that the EEC need to be replaced to up fit the larger displacement of the 351? Increase the fuel pressure and/or volume?
If I do this, I will need to change the ignition firing order to the 351, but what about the fuel injector sequencial positions (Speed Density Banks)? Would these matter as well????

Help Anyone!!!!

 

"its a 351 with a 302 firing order" What? Unless your truck came with a 302 HO (Didn't), your trucks 302 has a 1-5-4-2-6-3-7-8 firing order. Only the 302 HO and I believe, the 1995-1996 truck 302 uses the 352W firing order.

The 351W had a unique and distinct firing order (1-3-7-2-6-5-4-8 vs. 1-5-4-2-6-3-7-8). The firing order can never be changed unless you use a crank that is designed differently to do so.

From 1977 onward, the 351W shared the same head casting as the 302, differing only in bolt hole diameters (7/16 inch for 302, 1/2 inch for 351W).

If it's running rough, I would start with double checking your timing and firing order.

 

Thanks for answering.
A) timing is correct.
B) no internal or external vacuum leaks.
C) fuel pressure and volume is correct.
D) throttle body measures correctly.

So Im looking now at the fact that the EEC boxes are different for the 302 and the 351... I can easily install a 351 computer and change the firing order to the 351.. But before I go there I want to confirm the that the "Speed density Banks".. EFI wiring to the computer is not different.

Also I seam to have hit a wall as to finding out (learning) about each banks firing order....

Appreciate any and all help!

 

Your engine should have a physical distributor using a CAP and ROTOR and Plug wires.. The EEC just tells the system when to send the spark to the cap's center electrode.

The EEC will need to be changed as the speed density computer contains spark and fuel tables specific to the individual engine that comes in a particular vehicle. In your case, a 302 vs. 352 engine. Thus speed density systems are not adaptable to significant changes in an engine's volumetric efficiency. One you start adding cams, heads, etc. the computer cannot compensate properly because it is operating around a pre-set range of air volume which that particular engine will consume.

 

You can change the 351's firing order with a 302 cam, it opens the valve at the 3-7 and 5-4 pistons in the 302 order, it's not the crank, they look the same, just a longer stroke. With that being said, a 351 will go dangerously lean with a 5.0 computer, no matter how hard you tweak it. It does not have the fuel maps. Get the 351 eec. You might want to go mass air, it's an easy swap with the right harness and eec (donor trucks rock). The harness should be the same speed dens. to speed dens.