On Thu, 25 Jun 1998 21:27:31 -0400 code5 <code5@ibm.net> writes:
>Hello again--
>Anybody got an opinion on the subject of rimflo valves?
>I'm putting an early 1800cc head on a 1622 engine, smoothing the ports
>a
>little, adding the Moss HP cam, lightenning the flywheel. I'll get
>K&N's.
>The rimflos are quite a bit more expensive than stock.
>Burgess's book describes modifying stock valves the same way--taking
>material from the neck to improve flow.
>Not sure whether or not there'll be adequate payoff on a road engine.
Given what you've already done, Rimflos would be a good complement.
Granted, stock valves could (in theory) be modified, but the cost of
machining, etc would negate any price advantage. And it's not just the
neck being narrowed, as the difference between Rimflos and "stock"valves.
On big advantage of Rimflo valves is their "anti-reversion" ability.
That is, a higher resistance to back flow; ie. in the case of an intake,
flow from the chamber back into the port. This anti-reversion can, in
some cases make an otherwise "radical" cammed engine act as if it had a
milder grind cam at low speeds.
There is a very good discussion of Rimflo valves in Vizard's book on the
A series engine. While the specifics deal with the "A" series engine, the
principals apply to any engine, English or otherwise. Good reading.
Rick Morrison
72 MGBGT
74 Midget
>Thanks in advance for any thoughts.
>John Vallely
>
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