Originally Posted By: BrocLuno
I added a bit more info.
Also look at your tire diameter. These things are not geared low enough. If your door post says 3.55 - that'll be a weak feeling truck. They struggle - a lot. So maybe 265/70R15 is about as tall as you can go w/o pulling down the motor out of it's best torque range. This is not a combo that likes tall, skinny tires. Short and fat work better
Then look at the water pump and the rear timing case. If they are corroded and weeping, you need to replace them. It's not a fun job, but ... While you are in there, you can put in a new timing chain. If this truck has a bazzilion miles the timing chain is stretched.
That means the cam is running retarded. The factory cam is OK, and in fact, the Speed Density EFI system will not tolerate much more cam. So no gains there. But the motor can be made to breath better with the timing restored to where it ought to be and some steel roller tip rockers with 1.7 ratio instead of the stock 1.6 ratio. It's just enough bump to be good w/o messing up the EFI
Nailed a great deal of good points in your two posts
I can't remember if the trucks are batch fire or sequential, but the non-HO motors were generally turds and even the HO liked a few rev's to get any grunt out of her. Non-HO engines often received the nylon geared single roller chain which as BrocLuno noted, likes to stretch and retard the camshaft timing. You can test for this by seeing how much you can move the damper back and forth (you can probably move it by hand with a bit of effort) before the rotor turns. Go one way until you see movement, then go the other direction until you see movement again to get an idea as to how much slack is there.
Is the truck 2 or 4WD? You can often pick up gears on a Mustang board for cheap (I sold a set of 3.73's a few years back that I was just trying to get rid of), and something like 4.10's if you are doing mostly in-town driving will really wake it up. I had 4.10's or 4.11's in my '88 F-250 with a 302HO swap and she worked reasonably well, even backed by a non-lockup C6.
Depending on the miles on the engine, I'd be concerned that the 1.7's would potentially raise the risk of valve float. I've used them on all my Ford smallblock builds, but these are on engines with new or newer valve springs. That said, the Crane Energizer ones can often be picked up cheap, since they are pedestal and bolt into the stock location and are often regarded (and sometimes sold as, under I believe the FMS brand) the "Cobra" rockers, as they were OEM on the '93 Cobra IIRC. The rocker swap however does mean you need to check valve cover clearance (usually required a bit of work on the baffles on the 302HO with stock covers, not sure how it is with the stamped steel truck covers) and of course installing them requires the removal of the upper intake, and will necessitate the purchase of new gaskets. Might be worth the trouble if they are already leaking though. If ordering replacement valve cover gaskets, get the ones for the '96 Explorer, they are either rubber or silicone, can't recall off-hand, and will never need to be changed again.
Regarding your original question, I'd use Motorcraft plugs straight from Ford, gapped to the factory spec, which should be .052 - .056 for your 1994. If your wires are original, now is a good time to change them, along with the cap and rotor. Use OEM parts, the grey stuff tends to be pretty good.