GEN2.5 engine is basically the GEN2 engine with the Classic Inline's aluminum head on it. We swapped it on the GEN2 engine in one half a day without other modifications to the setup (except for the head, intake and carb of course). The head got the following goodies to it:

289/1968 valve springs

Ford 4.0L V6 retainers and Comp Cams keepers

A brand new adjustable Ford rocker arm shaft assembly

ARP head studs were used to attach it to the engine block

30-degree back-cut on the intake valves (HUGE gain in average flow to the intake port; highly recommended)

mild polishing on the bowls/chambers

The Classic Inlines intake manifold was attached as-is. The Holley 390cfm 4-barrel carburetor seemed to work the best with this combination, and in addition to complete overhaul it got the QuickFuel's secondary metering block (to be able to use regular Holley jets on the secondary metering system instead of the metering plate) and QuickFuel's adjustable secondary vacuum canister. These modifications really are very beneficial to ANY vacuum secondary type Holley 4-barrel carburetor, as they really give you the possibility to easily adjust secondary circuit's fuel and timing on this carburetor.

On the same dyno as all the previous dynos were run, this combination resulted to just shy of 180hp on the flywheel. The combination is not optimal as this engine was not built with the CI head in mind, and the compression ratio was not optimal for the camshaft being used. That said, pump up the static CR to 10.3 range and you can see 200hp out of this kind of engine with this camshaft.

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Block
'80 Mustang D8DE Ford 200cid 6-cyl engine
- crankshaft journals: -.010, new bearings Federal Mogul
- crankshaft checked for cracks, chamfered oil holes
- cylinders bored +.030 and honed
- deck milled -.030 for zero deck height
- Speed Pro 2.3L 4-cyl. HSC engine pistons (flat top) & Speed Pro piston rings
- connecting rods polished and media blasted
- connecting rod big ends honed
- connecting rod bolts ARP 289/302
- rotating assembly balanced (crank, damper, flywheel, clutch)
- ARP flywheel bolts
- flywheel clutch face machined
- cam bearings (std) Federal Mogul
- Ford Six Performance Parts 274-SDS cam (by Clay Smith Cams)
- duration 274/274 advertised, 224/224 @ .050 lift
- .456 lift with 1.52 rockers
- Sealed Power lifters
- Comp Cams timing chain

Head and valvetrain
- Classic Inlines aluminum cylinder head
- Sealed Power 289 V8 1968 valve springs
- Ford V6-4.0 engine one-piece valve retainers and locks
- standard adjustable rocker arms, 1.52 ratio
- Classic Inlines aluminum intake manifold for 4V carburetor
- combustion chambers polished slightly
- valve pockets ported slightly
- 30-degree backut on the intake valves

Carburetion & fuel/air delivery
- Holley 390 4V carburetor

Ignition
- '80 Ford Duraspark distributor w/centr. & vacuum advance
- MSD 6AL ignition module
- Ford Motorsport SVO Ultra Coil
- Ford Racing 9mm spark plug wires
- Motorcraft BSF42C plugs

Exhaust
- Ford Six Performance Parts single out headers w/ceramic jet-hot coating
- exhaust pipe 2.5" / 2.25", no catalytic converters
- Dynomax super turbo muffler 2.5"

Cooling
- V8 radiator
- Proform electric fan with adjustable thermostat