Phil...
You are already headed in the right direction to answer your valve
spring
question...Dave Anton at APT, "home"
of the Rimflow valve!
Had an interesting discussion on Cooper
"S" head valve sizes with one of the
old timers the other day working at
7 Enterprises.
The Cooper "S" heads sported 1.4 (or 1.414) intake valves and they also
went to
a larger than normal exhaust valve on
later heads sporting this larger intake
valve, assuming "more out" for the
larger 1.4 intake valve would mean better
flow and more horsepower. Well, it didn't...the larger exhaust valve did
nothing for power at all.
This would indicate that exhaust port
"velocity" was more important than exhaust port "mass flow" and was
"right"
for the larger 1.4 intake valve, the stock
engine's exhaust valve size actually being
a little larger than it had to be in the first
place.
So, on the very latest of the old 1275
Cooper "S" heads, they went back to
the smaller original exhaust valve, thus
returning a little bit of structural strength
to the metal area between the two valves.
This also made it possible for aftermarket
suppliers to go to even larger 1.44/1.46 and even 1.48 (racing) intake
valve sizes.
bearing in mind the area between valves
would be subject to failure (cracking) to that extent.
Dave Anton would also know the story on
this I'm sure, and can definitely advise you on the "softer" valve
springs to be used with the 1.5 rockers as well depending upon "lift" of
the intended cam
profile.
The Rimflows are designed to minimize
"reversion" with respect to maximizing
"proper" flow so their effectiveness will
be related to cam profile in terms of
duration....here again, Dave Anton is your
best bet for information in this respect.
Cap'n. Bob
'60 :{)
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