I found this in the FOT archives. Jack Wheeler wrote..
"For what it's worth, I will give you my experience with a TR-4 full race
engine. Prior to 1985 I had used springs in the carbs (1 3/4 SU H6's) and
automatic transmission fluid in the dashpots. In 1985 we put the engine on
a dyno and found horsepower improvements at top end by taking the springs
out all together and running the dashpots dry. I was initially concerned
about driveability at speeds other than full RPM, but after the change, the
car was quicker throughout the range, with no loss of performance at any
RPM range.
Also when the carbs were set up by Dick Stockton, he drilled a 1/8" hole in
the brass cap on the top of the dashpot, and cut the stem off that goes
down into the dashpot with the damper on it. I ran the car this way for 15
years and never had any problems.
For those of you not familiar with me, this car won at the SCCA Runoffs in
1990, so was pretty quick with this setup."
Catpusher@aol.com wrote:
I found my current cans of SAE 20 in an Ace HW in Florida, and use this in
street motors
that call for this.
Dyno results for my TR3 87mm HC full race motor for both 1.75" and 2" SUs had
wild
SU piston flutter and power loss with minimum damper action; much better
results
with SAE 20 oil, and the best with type F ATF & STD piston springs
The motor power band is 5500 to 7200
TR6/Spit (or RX7, HD 2 wheeler) results may differ.
BTW: the TR4A (TR3B Mk III) center pull set up is vastly superior to the
earlier set up.
I wonder what the SCCA rule book would think about an alum TR3/4 front engine
plate?
I drilled mine full of holes, also for air flow; really bent a couple too
(safety strap?)
More than one MGB racer that tried that for the rear plate (real weight
savings) was called on it.
If you race with OD; I Highly recommend running a Safe, full time, pressure
gauge. Really!
For the A type, the lubrication oil only starts working once the accumulator
piston has made it to the blow-off drillings, so too high a set pressure is
not good.
I ran an interesting OD cooling system that even helped speeds in the ATA
bridge turn.
Hardy
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