See hipomustang.com/images/hipoeng/
"Other
than the cup the castings the (HI Perf 289 heads) were absolutely ordinary 289 4V heads. Same
combustion chambers, same ports, same valves, same everything." The High Perf heads like these heads have push rod guide
holes cast in the head these were standard in 1965 but eliminated in 1966. Use of
the push rod guides "meant they could use ordinary non-hardened
push rods.
Screw-in vs. push-in studs was just a matter of machining the casting." If you want to go to screw in studs, you can remove the pressed in studs
by putting a socket on top of the bare stud a washer than a hardened
nut. You then put ice on the head and tighten the nut which will pull
out the pressed in stud.
C7ZE-A
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67 289 Hipo
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Valves 1.67, 1.45
54.5cc |
| " Outside of the five-to-six-bolt bell housing pattern change for 1965, the next most significant change for the small-block Ford is valve train and valve covers in 1966. On May 8, 1966, Ford went to a rail-style rocker arm on the small-block Ford. Instead of a push rod guide hole cast into the cylinder head, the rail-style rocker arm sat on a taller valve stem, which kept the rocker centered on the valve. At first thought, this is a good idea. But, when you consider engine wear and the possibility of using a high-performance camshaft, this idea is a bad one. As the valve stem tip wears, the side rails get closer and closer to the retainer. Eventually, they work their way into the retainer, which can fail, drop the valve, and destroy the 289/302" source diyford.com/choose-heads-small-block-ford-rebuild/ see How to Choose Heads for Your Small-Block Ford Rebuild.
1965 289s were HIGH COMPRESSION engines, putting these 54.5 cc chambers with 1.67/1.45-inch valves on a later 302 engines will raise the
compression. You will need to use 93 octane fuel. Small-block
Ford cylinder heads began to change significantly in the 1970s, where you
need to pay even closer attention to casting differences. Port and valve sizes
remain virtually the same for 289/302 heads through the years, but combustion
chamber changes a lot after 1971, chamber size volumes got larger. When
combustion chamber size increases, compression drops. Ford, as well as all of
the U.S. automakers, dropped compression to both improve emissions and deal
with steadily falling octane ratings due to the elimination of lead, but with a
corresponding drop in horse-power. These are not smog heads and therefore they have no ports for air
pumps and will not pass California
emissions. Ford 260 heads had even smaller chambers but
also smaller valves and ports so obviously not a good performance choice.
Note the push rod guide
holes cast in the head as these heads do not use rail style rockers. FORD high performance 289 and 302 engine heads
all have cast in valve guides that were machined and were never fitted with the
heavier rail-style rockers. When it comes to the 289- and 302-ci
engines, port sizes never changed, nor did valve size (except for the
BOSS 302 which used 351 "Cleveland" canted valve heads). Contrary to all you’ve heard through the years from you buddies, the
289 High Performance cylinder head does not have larger valves and ports.
Combustion chamber size isn’t any different from the 2V and 4V head either.
What is different is the performance heads all have cast in valve guides and do
not use the rail style rockers and the Hi-Perf heads had screw in studs. If you are going to use a high lift cam you do
not want rail style rockers. In non-performance
heads the cast in guides were eliminated necessitating the use of rail
style rockers but saving ford a lot of machining and therefore money but
also reducing rpm as the rail style rockers are heavier and sloppy at high RPM
due to the lack of the precision valve guides. Note the last picture shows a rocker comparison between the heavier rail rockers and non-rail rockers.
You will have to use performance style rockers without
rails, which unless you already have high performance heads you will need to
buy new high performance oem or aftermarket rockers such as Crane and probably new push rods as well because your old ones probably have worn down tips as without
guides the push rods wear down and may need to be replaced.
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