LaJoMor@aol.com wrote:
>
> Moss lists it as a PCV valve as does Victoria British. I think the term "gulp
> valve" is British, not American slang.
> Moss lists it for TR250 application for $17.95 while Victoria British lists
> it at $59.95. I don't quite understand why the great difference.
If they are listing a PCV valve as a "gulp" valve, or vice-versa, that's
incorrect. A "gulp" valve is indeed American slang for a diverter valve,
sometimes called, in earlier days, an anti-backfire valve.
It first appeared on cars when exhaust manifold air injection was
required for emissions purposes. However, introducing fresh air into the
exhaust manifold on decel caused backfiring (due to small amounts of
fuel introduced into the engine by the idle circuit and high vacuum), so
the injection air is "diverted" momentarily to prevent backfiring. The
name comes from the sound made when the valve was shunting air from the
air injection pump to the atmosphere during that brief period of decel
when backfiring was likely.
When catalytic converters were later required, most manufacturers placed
the air injection port nearer the converter, rather than in the
manifold, to reduce the amount of heat generated at that point. With the
port that far down in the pipe, some manufacturers could, on some
engines, do away with an air injection pump, and place an educted reed
valve in the air cleaner as the fresh air source, using exhaust gas flow
to pull air into the system. These valves also were generally called
gulp valves because they make a burbling sound at idle which can be
heard when the air cleaner housing top was removed.
PCV valves, to my knowledge, have always been called just that--PCV
valves, or positive crankcase ventilation valves.
Cheers.
--
Michael D. Porter
Roswell, NM
mailto: mporter@zianet.com
`70 GT6+ (being refurbished, slowly)
`71 GT6 Mk. III (organ donor)
`72 GT6 Mk. III (daily driver)
`64 TR4 (awaiting intensive care)
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