OK, recently bought a 1993 F150 ext cab XLT with Mark III option and 5.0 High Performance engine. Does anybody know anything aout this option? The PO said it was rated at 210 HP. Can't seem to see anything different about the engine, looks just the same as my old 5.0 in a 1990.

 

As far as I know, the Mark III option didn't have any kind of engine modification, it was all show. A 5.0 HO does exist though. They put them in Mustangs. They're good motors in a car, or a lighter truck. I'm pretty sure the HO 5.0 motors said 302 HO on top of the motor, so it would be visual unless it's changed. I believe that the HO motors were like 220 horse and 300 ft/lbs of torque, something like that. But I'm pretty sure those 5.0 motors in trucks were rated for right around 200 horse, maybe a little more in that time period.
If I'm wrong, someone will correct me.

 

5.0L H-O eng. began useage in late 1980s w/ fuel injection, my 1989 had roller camshaft, but not roller rocker arms. This continued up till 1995. However, in 1993, Cobra was re-introduced, WITH roller camshaft AND roller rocker arms, as well as larger capacity fuel injectors.

Regular 5.0 H-O engines in Mustang had 19 lb/hr injectors, Cobra had 24 lb/hr, requiring DIFFERENT calibration of computer. 5.0 HO was rated nominally 225 HP, Cobra 245 HP. impish

 

The only difference that i knew of between the regular 5.0 and the H.O.'s, was that the H.O. had a different taller cam lobe and firing order. Allowing it to breath better and run smoother, while making more horsepower.

 

5.0s in trucks did not come with roller cams. The firing order was also different, actually, the old, familiar Ford V-8 firing order from years back.

5.0 H-Os as used in Mustang (and maybe Lincoln), had a REVISED firing order, which Ford claimed RELIEVED some load on the FRONT MAIN BEARINGS. Thus, messing with interchanging camshafts causes plenty of confusion, due to the firing order difference, not to mentioon the fact that H-Os had STEEL gears on the distributor shafts, which would EAT the cast iron gear of the flat-tappet camshaftr, if used with an H-O distributor gear.

(watch the locations of those plug wires, guys!).

impish

 

You were LIED to. The MarkIII conversion was cosmetic ONLY.

BUT an easy way to tell if you have a5.0 HO in your truck would to look at the plentum. If it goes over the passenger side valve cover it is NOT. If it goes over the drivers side vale cover it IS

 

....The 94 + truck 302s had roller cams , and some had mass air and sefi , the cams were just samaller than the HO cam , they have the same firing order as the HO and used the steel cam gear for the steel roller cam....

 

Actually some trucks were equipped with roller cams as early as '92 but it was the tiny Crown Vic cam with the old firing order, these trucks were the dumping ground for all kinds of leftover bits unfortunately.
As for the PO's question about his MK3, you would know if you had a HO.. the truck would really haul with the hammer down.