when and what did the 302 roller block into being?is there any one year or model that is better than another?  

The Ford 5.0 roller block started seeing production in 1985 in the Mustang. There are HO roller engines and non HO roller engines. The block is the same, with no major changes through its production run. If you are looking for a short block or a good used engine to drop in and go, then the '87-'92 5.0 Mustang engine is the best. It has forged pistons with valve reliefs and the higher flowing E7TE "truck" heads on it. The '93 went to hyperutectic pistons (not bad as long as you don't use big blower or nitrous). If you're only looking for a roller block to build from then a non-HO application would work for a starting point.

HTH...
Mark  

thanks for the info. are all the cranks the same? what i'm looking for is a good starting place for a 68 fastback i'm building.  

In 1982, Ford switch to a 50 oz balance weight from the old 28 oz on the 302.  Crank, balancer and flywheel (or flexplate) have to be from the same era to avoid a big balance problem.  After that, a 302 crank is a 302 crank.  later models also use a one piece rear main seal - I think that's a change in the block casting and not a design change to the crank.

If you mix and match parts or build from scratch, have the rotating assembly balanced anyway.  

thanks for the info...50 oz. vs. 28oz was going to be the next question.  

76twister, 5.0 was introduced in 1982 when Ford decided calling 302 a 5.0L when they went metric system. Roller type did not start until 1985. My last two engine build was a 1989 and 1990 HO because they sported more stock horsepower than their siblings. Here some facts that I got from the web. Hope it help answer your question.

5.0 High Output -- Chronology of Changes
1982 - 157 HP @ 4200

Introduction of the 5.0 High Output engine
Lighter (120 lb.) thin wall 302 block, with old-style 2-piece rear main bearing seal
Reciprocating assembly changed to utilize 50 oz.-in. unbalance flywheel and 34 oz.-in. damper
Cast pistons, 8.4:1 C.R.
Heads with smaller "high velocity" ports and valves
"1973 Torino" profile flat tappet camshaft, duration 260° intake, 278° exhaust, lift of .416" intake, .444" exhaust
Double row roller timing chain
Aluminum intake manifold
369 cfm Motorcraft 2-barrel carburetor
Dual snorkel, high dome cover, low restriction element, air cleaner
Cast iron exhaust manifold with a 2" outlet, 2.25" Y-pipe

1983 -- 175 HP @ 4200

Same camshaft, exhaust manifolds, and pistons as 1982
600 cfm Holley 4180C 4-barrel carburetor and aluminum intake manifold
New block and crankshaft to use a one piece main seal introduced mid-year

1984 -- 175 HP @ 4200

Generally the same as 1983
Redesigned choke, eliminating heat tubes from the manifolds

1985 -- 210 HP @ 4400

Hydraulic roller tappet camshaft introduced. 266' duration, .444 valve lift
Revised block (122 lb.) with two retainer bosses for roller tappets.
New cylinder heads, revised to allow service removal of the roller tappets
Distributor drive gear material changed to be compatible with steel camshaft
Forged pistons with low tension rings and thicker ring lands. Compression remained at 8.4:1
Holley 4180C carburetor, with improved secondary metering
Water pump impeller diameter increased to 4.4" for increased flow
Stainless steel tubular headers

1986 -- 200 HP @ 4000

Stronger block (126 lb.) incorporating "squared bores" for better oil control.
Compression increased to 9.2:1 with flat-top pistons
Masked intake valve, high-swirl cylinder heads, casting # E6AE-AA. This head was also used on 1986/91 normal passenger car engines.
Roller cam same as 1985
First year for multi-port speed density fuel injection, 58 mm throttle body, 19 lbs/hr. injectors
Dropped cold start exhaust control valve, header outlet size changed to 2 1/4"
New water pump with exit scroll and more efficient impeller.

1987/88 -- 225 HP @ 4000

Same Camshaft, exhaust manifolds, and block as 1986
Truck casting wedge cylinder heads with revised combustion chamber, casting # E7TE-AA, used through '95
9.0:1 compression forged pistons with valve eyebrows
Speed Density EFI with same intake runners, larger crossover duct, and 60 mm throttle body

1989/92 -- 225 HP @ 4000

Same block, heads, intake and exhaust manifolds as 1987
Introduction of the 55 mm Mass Airflow fuel injection system. Since this system measures the actual air flowing into the engine, high performance camshafts may be used.
These engines offer the greatest performance potential of the 5.0 H.O. series
In stock trim, the small 55 mm MAF & revised camshaft actually limited breathing, so it was no longer producing 225 HP.

1993 H.O. -- 215 HP @ 4200

Mostly indentical to 1989/92 engines
New cast hypereutectic aluminum pistons, lighter weightand greater hot strength
Hi-torque, mini starter
Advertised horsepower dropped due to the incremental changes.

1993 Cobra -- 235 HP

Same cast pistons as 5.0 H.O.
Cast iron GT-40 heads
Shorter duration, higher lift camshaft
1.7:1 ratio roller rocker arms
Cast aluminum GT-40 style intake
65 mm throttle body, 24 lbs-hr injectors, 70mm mass air meter
Special type exhaust manifolds
Specially programmed EEC-IV

Small Block Balance Considerations

Small block reciprocating assemblies have external balance. The crankshaft itself does not carry enough counterweights to achieve zero balance. Extra counterweighting is cast into the flywheel and harmonic balancer bring the entire assembly into neutral balance. Early engines use 28.2 oz.-in. external balance, while 1982 and later engines use 50 oz.-in. at the flywheel and 34 oz.-in. at the damper.

Automatic transmission flexplates have a welded-on weight plus a cutaway window on the opposite side. Rivets are used to fine-tune the balance.

When converting from automatic to a manual transmission, be sure to use the correct flywheel bolts. Those specified for use with an automatic transmission flexplate and stiffener are not long enough.

Current Ford Master Parts Catalogs specify part # D2AZ-6379-B bolts for both flexplates and flywheels. They are not long enough to properly clamp a manual transmission flywheel to the crankshaft. Don't trust 'em.

Obsolete but still available part # B8AZ-6379-A is the correct grip length. These bolts come with thread sealant pre-applied.

The cast iron GT-40 cylinder heads may be identified by casting marks shown here. These GT-40 heads are casting # F3ZE-AA. Small block cylinder head casting numbers are found on the underside of the part, between the pushrod holes.