> The one MAIN diffeence in the 440 6-bbl motor was the camshaft had the same
> duration as the regular HP cam, but had a lower taper on the camshaft lobes
> for them to better tolerate the heavier valve spring pressure. The cam lobes
I thought the original 6-pack in 69 had a larger cam than the HP. Will try to
check back in the books.
>
> According to the dealer's Data Book, the 400 and 440 HO motors also had
> double-roller timing chain sets. The moly-insert compression rings are
> listed in there too, but probably pre-date those motors too.
My 68 shop manual does not indicate any differences in the timing chains, piston
rings, or bearings between the two engines in the specs section. Could these
differences be for later model engines?
> What the chrome/moly ring is, is a normal chrome compression (top ring) that
> has an area in the middle of where it contacts the cylinder wall that has an
> area impregnated with molybdenum for added scuff resistance under high
> rpm/high load situations. The moly is somewhat porus and keeps oil in it,
> plus being an excellent lubricator itself. These "chrome/moly" rings have
OK, I got confused. The word "insert" actually refers to plating. The "moly"
piston ring plating replaced the hard-chrome plating on the cast iron piston
rings some time recently (cast iron was and remains the best core material for
piston rings). All 68 440's used chrome plated compression rings according to
the 68 shop manual. May be in later years they shifted to "moly". Both types
of plating increase the hardness of the piston ring in the area it engages the
bore. The main advantage of the moly over chrome plating is that it breaks in
a lot faster, and its also better for frequent dry starts. The chrome plated
ring is still superior in heavy duty applications, and is still used in heavy
duty diesels.
The other differences between the HP and non-HP that we forgot were the
different exhaust manifolds and dual snorkel air cleaner (the second probably
made a larger difference, and any air cleaner can be easily "modified" to HP
specks).
D^2
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