>From time to time questions come up regarding Weber carbs for these
cars. For what it's worth, I will share with you what I learned at the
flow bench ($$$$) while preparing a TR4 for racing.
The following are flow figures in cubic feet per minute, using 10" water
vacuum on the flow bench, on STOCK PARTS:
SU stock = 148 cfm
Stromberg stock = 152 cfm
Short manifold = 108 cfm
Long manifold = 115 cfm
head port, valve at .300" lift, no manifold = 75 cfm
What does all this mean? Well, for starters, the restriction in the
intake passage is at the valve.
According to the data, Weber carbs, with their increased total choke
diameter, will not increase total flow, and because of decreased
velocity may in fact diminish actual horsepower. In addition, my
findings were that (hold on to your preconcieved notions!!) careful port
matching adds almost nothing to flow. I wish I had back all those hours
and Dremel stones!
I wish I had data for all you TR6'rs, but I don't.
Of course, we all know Webers look great and I'd love to have a set to
play with, but on a stock engine, the data says they won't help.
With highly modified ports, and especially with cams that lift the valve
.500", it may be a whole different ball game.
Cheers!
uncle jack in Iowa, waiting for the first lap
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