Well, Frank-
Well you should wonder!
These valves improve flow wherein flow
"reversion" usually upsets same in terms of efficient cylinder filling.
"And where might that be, Sir Bob?", you
might ask.
That would be at the lower end of the rpm
scale with long duration cams. What "anti-
reversion" (Rimflow) valves do is bring the
engine onto the camshaft profile sooner
by promoting "one way" (read.."correct" way!) flow below the point
wherein the
engine is "on the cam" and exhaust tends
to contaminate the incoming charge by
going the "other way" as the intake valve
opens. Without Rimflow-type valves, the
lower range usually has to be made "richer" to counter this "dilution"
of the
incoming charge, so these valves also
allow a "leaner" lower range while maintaining smooth response "off"
cam.
If I recall accurately, you are running a
Kent 276 which is a little more tame than
the Vizard VP3 I used in my "60" over
1275 with 1.5RR's. On the other hand, how much driving do you do in
heavy
traffic considering your geographical location wherein the Rimflows
might make life a little easier for you in this
respect? If you are running a Kent 286,
I'd definitely opt for Rimflows (1.414's at
that) and most especially with 1.5 rockers,
traffic conditions notwithstanding.
Incidentally, if you do use the larger 1.4+
intake valve (if you are not doing so already) don't bother opting for
the slightly
larger exhaust valve over stock, as trials
conducted in the Cooper S showed absolutely no more power was made going
to a slightly larger exhaust valve
wherein the 1.4+ intake valve was used.
Cap'n. Bob
'60 :{)
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