Ron:
I would not make too much of the TR6 head supposedly poor flow.
The earlier high compression heads had less than optimum flow, but the
later
low compression heads got all the goodies - deshrouded exhaust valve, improved
port design, better cooling, improved intake manifold, etc. Of course, this
was all done to make up for the reduced compression ratio to meet federal
emissions.
Take a look at Vizard's book "Tuning Standard Triumphs over 1300cc".
You will
see that the later heads had little that could be done to improve flow,
although the poor tolerances in the casting somewhat belied this. One could
clean up the poor castings and get some flow improvements. But note that the
TR6 heads came from the factory already gasket matched. While the flow
benefits of gasket matching are overstated, it does show that the factory boys
knew what they were doing. Also the combustion chambers have healthy squish,
something that was not appreciated by Detroit for another 20 years.
Likewise for the Zeniths. They are emissions carbs, but the details are
there. The bypass valves for example, are implemented in such a way that flow
is not reduced through the carb. Compare the SU solution for deceleration
bypass, and the flow through the carb is dramatically reduced since SU elected
to mount the valve directly on the butterfly. Simple yes, but it sure kills
air flow through the carb. The SU solution is so bad most users simply elect
to remove it rather than deal with the performance penalty.
If I was going to criticize the Zenith, it would be for the rubber
diaphragms. Unfortunately SU had a patent on the piston solution, so Zenith
was forced to find a method that did not infringe. The result is that we get
to live with the limited life of rubber, and its attendant vulnerability to
pinholes and tears.
Vance
Vance Navarrette
http://www.triumphowners.com/832
-----Original Message-----
Subject: Re: [6pack] DUAL WEBER 45 MCHH TRIUMPH CONVERSION KIT
At 10:56 AM 5/28/2010, ron wrote:
>I'm not sure about the Weber carbs, however, if you are going to
>take care of the poor flow characteristic of the TR6 head, it seems
>you would want to put a better intake manifold on in order to give
>the gas/air mixture a straighter shot at the intake valve. The Good
>triple carb intake does that and the Strombergs or the SU's are a
>lot easier to tune.
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