Ron...
Your question is a little outside my relm
as my 90hp at the rear wheels Vizardized
(for the street) Series A was a later thick-
flanged varient, bored "60 over".
However, it may be interesting to note
that Bill Perry of Rivergate
will not accept the early "thin flange" 1275
engines as "cores" with respect to the
engines he builds for the street market
and will not build upon them in any case.
On the other hand, I subjected my thin-
flanged stock 12cc with 55K+ on it ('67
Sprite) to around 5,000 miles of hard
Judson blower experimentation right
up to the redline on more than several
occasions. I mean, Ron, I really beat the
hell out of it with both 4 and 6psi boost curves. It was the only way to
test the
efficacy of the application. Several times
it was exposed to detonation/pre-ignition
as we experimented to get timing and
plug ranges sorted out. It simply could
not be avoided though we didn't push
it when we ran into this, of course.
Several times we had the water temp
to an indicated 210 in these experiments but that was as high as we
would allow it
to go before backing off.
No problems!! These engines have a
reputation for not being stiff enough but
you couldn't prove it by this particular
12cc motor. Perhaps "bore flex", etc., is
a problem with overbores past "20"?
After we finally removed the blower and
went back to normally aspirated, it performed just fine for another
couple of
thousand miles right up until the time
the car was totaled after being bounced
off I-95 by a rather large truck!! No oil
burning or loss of oil pressure and it
still produced 150psi across the board
and went as well as it did prior to it's
temporary Judson days.
We did ship it to Bill Perry to salvage what
we could against the new Rivergate
motor "tailored" for the Judson application as to head, connecting rods,
crank, etc.
Turns out it did have a nitrided
crank and had been previously turned
by "10" on all bearings. Whether
the crank had been re-nitrided when
turned (I hear this treatment only goes
down "10") I do not know.
Cap'n. Bob (Ret'd)
'60 Frog
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