this should answer alot of your questions http://www.maverick.to/mmb/showthread.php?t=36034 welcome abord by the way
Yeah, i thought HO was when the roller cam/timing set came out on it. I don't think the trucks got the roller and stayed 5.0 but some of the cars got the roller and the HO badge. Was supposed to be a 30-40 HP increase. Anyone verify that?
HOs got the roller cam before any other engine. HOWEVER, the EFI car engines got rollers pretty quick... by around 87-88. Trucks got the same roller block early on, but didn't get the actual roller cam until around 93. So, 20 years later, I wouldn't make a blanket statement like "only HOs had roller cams". It depends on what years you are comparing, and there were only a couple where that rule holds true. Edit: I want to clarify that the passenger car roller cams and truck roller cams use the 'old' 302 firing order we are all used to. Only the HO had the roller cam combined with the 351 firing order. I am honestly not familiar with 302/5.0s after 95, so the rules might change after then. But by that time, 302s were pretty much only an Exploder engine.
Trucks had flat tappets into the early 90s, but they had a true roller chain and a roller cam block. The cars got the mild 302 firing order roller cams fairly quickly. They used the same fuel injection as the HO, but the upper manifold was installed 'backwards' and the top plate didn't have the HO lettering. Cars that actually got the HO were Stangs, Capris, and Lincoln Mark series cars. I am not sure, but I believe the HO was also a T-bird/Cougar option during some years, but don't quote me on that. Someone else will have to confirm the HP difference. It probably was as high as you say when compared to the VV carb'd, flat tappet, low compression, poor cylinder heads, of the other 302s available when the HO first came out with it's 4v carb, roller cam, and the first variations of what became E7 (then GT40) heads. IIRC, the best HO roller cam ever used was 85(4v)-86(SD EFI). When the EFI went MAF in 87, they tamed the cam. Edit: I am behind the learning curve on Ford V8s after the 70s, but I am figuring it out now that I own a few later engines. I may be off by a year here and there, but that's the basic history, and the engines I have now, bare that out.
I have seen an HO in a T-Bird that I want to say was a '92. Almost bought that car to snag parts from. Are the HOs the only ones with forged pistons? Explorers are getting very easy to find in boneyards but I'd rather have forged pistons if they are easy to find.
To back up what Dave said, I have seen more then one late 80's Town Car in the junkyard with roller lifters. It seems to be hit and miss in '86 and '87 and up seems to be mostly roller blocks in the non HO engines. I know the '88 Grand Marquis my grandma bought new has a roller engine in it. There are a ton of mid-late 90's Explorers showing up in the junkyard lately. Problem is, out of literally 100+ of them I have seen, only one had a 5.0, and it had been stripped to a short block and was rusted up from sitting with no hood. Most have 4.0 V6's. I've came across probably 30 or 40 of the early 90's HO T-Birds in the past couple of years and probably about the same number of HO Lincolns Mark VII's.
Yup, Ford began to offer the H.O. in T-Birds/Cougars in 1991. They had to use a more restrictive intake and exhaust for packaging reasons, so they were rated at 200hp. The full size Fords/Mercurys/Lincolns got the roller cam in 1986. They were rated at 150hp (165 with dual exhaust). The trucks were rated at 185hp, but I can't remember when they went roller.
It started in '82, and varied over the years. H.O. engine appeared with the reintro of the GT version of a Mustang-first since 1969-in the year 1982. http://www.mustanggt.org/82gt.htm for details on the '82 GT. 1982-"the HO engine debuted along with the reintroduction of the GT nameplate. Available in 3-door hatchback only, the GT featured the first true "HO" 302 as standard equipment. The major upgrades and design changes which distinguished the new 157 horsepower HO 5.0L engine from its 302 predecessor, and provided 17 additional horsepower were a 2V Motorcraft carb (369 CFM) fed by a dual snorkel, high lid air cleaner, an aluminum intake manifold, a more aggressive camshaft with a double row roller timing chain, larger and deeper nylon valve stem oil seals and 8.4:1 CR sandcast pistons. While it was rumored that the camshaft used in this engine was a marine cam, in reality the marine cam was ultimately rejected for actual production due to low torque numbers. The camshaft actually used was a design used previously in a 351 Windsor two-barrel passenger car V-8 (more specifically the 1973 Torino). Other features of the 5.0L GT included cast iron exhaust manifolds dumping into a single muffler with dual outlet exhaust (“Y” pipe with transverse catalyst), SROD 4-speed overdrive transmission, a 3.08:1 Traction-Lok rear axle (7.5 inches) with factory traction bars and a beefier TRX handling and suspension. 157 HP @ 4200 RPM 240 ft/lb @ 2400 RPM 1983-the car got a 4V Holley carb. 1984-no change motorwise 1985-addition of a racing-style roller lifter camshaft, stainless steel tubular exhaust manifolds and forged 8.4:1 pistons (replacing sandcast pistons) with thinner, lightweight rings to further reduce friction. Of course, these changes necessitated a revised block and heads to accept the taller roller lifters. Exhaust restriction was reduced by splitting the exhaust pipe behind the catalytic converter and adding dual mufflers and tailpipes. Automatics still came only with the lower performance 302 HO and throttle body fuel injection, even though horsepower was upgraded to 180 hp early in the model year. 1986-Replacing the tried and true 4V carburetor was a sequential multiple-port fuel injection system perched atop a revised 302 HO V8 block. This engine was installed in both the manual transmission and automatic overdrive units with horsepower now equal for both. Although horsepower was down 10, torque was up 15 foot-pounds. The compression ratio was increased from 8.4:1 to 9.2:1 with new forged flat-top pistons and redesigned cylinder heads featuring a new fast-burn combustion chamber. While retaining the roller lift cam and stainless steel tubular headers, the new fuel injection setup featured a 58mm throttle body (540 cfm) with 19 lb-hr. injectors and a tuned length aluminum intake manifold. A new H-pipe feeding dual converters lowered backpressure an astounding 32 percent. The old Duraspark ignition was replaced with a Hall Effect distributor to be compatible with Ford's EEC-IV computer, in its first year in the Mustang. Maybe this helps. Any factory 302 in a Comet/Maverick never had any of these go fast goodies. Seth
