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September 12, 2003
Well said, Don May...
You hit the nail on the head..exactly
spot on.
This is the position I found myself in,
more or less.
Prior to knowing about the Datsun 5 speed, I attacked "the problem" by
moving the whole rpm range upscale
to 7-7.5k rpm by "Vizarding" a 1275
and making 4-4.5k rpm a comfortable
cruising rpm. Supertuning the motor
to take higher rpm is not inexpensive...
for it's operating range is just short of a track motor. Weber 45DCOE,
bigger valves, prepared head, VP3 cam and
1.5 rollers, big bore LCB and large
diameter free-flow exhaust system to
match...all teamed with the 3.7 diff.
Knowledge of the Datsun 210 5 speed
conversion together with an assortment
of diff. ratios changed all that, while
allowing for much more quiet operation
and 1/2 the cost of future gearboxi, once
costs of the initial 5 speed conversion are
behind you. Of course, since the Datsun
box is so well built and was originally
designed to handle the power of a 210,
you may never need another "rebuilt" once the initial "rebuilt" is
installed! :)
Load-wise, it is high rpm which wears
down motors, most especially in the
case of 3 main bearing 4 cylinder motors
as opposed to 5 main bearing types.
This is the theory behind low pressure
supercharging (Judsons, Shorrocks, etc.)
as an alterntive to high rpm "tuning" for power. When you use the
latter, you have
to keep the rpm up (4.22 or 3.9) to stay within the "uprated" higher rpm
power
range.
With low pressure supercharging, you
can use a 3.9 or 3.7 and
get plenty of "go" from a stock engine
while enjoying lower cruise rpms, most
especially when this is teamed with a
5 speed! Best of all worlds, IMHO!! :):)
A simple Cooper "S" tune combined with
a 5 speed through a 3.9 or 3.7 works just great all around in my type of
current
use of the BE.
This "tune" is bascially what Rivergate
offers in it's street performance rebuilt
1275's it offers to the Spridget public
at a reasonable price (NFI...it just "is
what it is"!!:).
Throw a couple of more goodies in (alum.
head, med. bore LCB header and free
flow exhaust) to improve the flow a bit,
and you could use a 3.55 instead of a
3.7 for even easier cruise, and still have
plenty of zip for acceleration, considering
those first 3 gears in the Datsun box
are, after all, a little bit lower than the
than those you find in the stock ribcase.
You can see why I love the 5 speed as
an alternative gearbox!! Options, baby,
options!! :):)
Cap'n. Bob
'60 :{)
PilotRob@... 25209
Posted on September 12, 2003 09:22 AM
Posted to category(s) Body | Carburetor | Cylinder Head | Drive Train | Electrical System | Engine (external) | Engine (internal) | Exhaust System | Interior | Miscellaneous | Restoration | Transmission | Tuning
