Info scraped from
http://lists.twistedpair.ca/pipermail/classic-mustangs/1998-March/009799.html
BLOCKS
HiPo blocks are said to be cast of higher nodular iron. What I've been
told that this means is that Ford closely examined the blocks that they
cast in their regular process, and selected the best ones for HiPos
(perhaps some sort of visual/other test/check?). HiPo blocks can not
be positively identified by their casting numbers. At least some are
identified by an orange paint daub (don't remember the location).
BOTTOM END
- CRANKS not forged steel, but again of a higher nodular iron. As above,
this means that Ford selected the best of the ones they produced to be
included in HiPos blocks. Brinell tested for hardness. Additional
counter weight on the end
- HARMONIC BALANCER is larger (I believe almost 1" thick)
- MAIN BEARING CAPS were 2-bolt, but larger than std. 289. No distinguish-
ing part #s. Can be transfered to other blocks, but requires align boring
(expensive and probably not worth it).
- RODS were heavier duty; very similar to those used in the Boss 302 years
later. Larger bolts, 3/8" I believe (as opposed to 5/16" for std.)
- PISTONS were cast flat tops, yielding higher compression.
HEADS
- 289HP "cast in" heads between the lifter bores
- SCREW IN STUDS mounting rocker arms
- CAST IN SPRING SEATS
- ROCKERS: never switched to rail-type like std. 289; uses "close tolerance"
push rod holes.
- MECHANICAL LIFTERS, wilder camshaft (something like 310-degrees duration
and .45x" lift - intake & exhaust). Stiffer springs, etc.
- VALVES are the same size as other 289s (1.67" intakes B4 early 65; 1.78"
intakes there on).
INTAKE
- SAME CAST IRON INTAKE MANIFOLD as A-code 289.
- CARB: Autolite 4100, with 1.12" venturis, flowing ~600cfm.
Different from A-code 289 (1.08" venturis, flowing ~480cfm)
- OPEN ELEMENT 14" air cleaner, chromed top
- MANUAL CHOKE operated from inside the car
EXHAUST
- Unique to 289HiPo freer flowing cast iron exhaust manifolds
Very few had plumbing for heat riser to carb
- Used different H-pipe
- All had dual exhaust (65-66 style, Shelby style, or 67 style)
DISTRIBUTOR
- Dual Points - No vacuum advance
ALTERNATOR
- Larger pulley (~4"), higher rating
TRANSMISSION
- Manual only until '66 model year
SUSPENSION
- Springs, shocks had increased rates. Most (if not all) have a 9" rear
APPEARANCE
- Chrome plated steel or "Cobra" aluminum finned valve covers.
- Chrome Air Cleaner w/289 High Performance decal
- 65-66 289 High Performance Fender badges