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Re: Bypass Valve

To: 6pack@autox.team.net
Subject: Re: Bypass Valve
From: Timothy Holbrook <tjh173@yahoo.com>
Date: Sat, 10 May 2003 09:55:09 -0700 (PDT)
I too have my bypass valves "bypassed" by blocking them with gasket
material.  The purpose of these valves, as others have noted, is simply
an emissions control to help reduce certain emissions that occur in
high vacuum situations on "overrun", when your foot is off the gas but
the engine rpm's are high.  It allows air/fuel mixture to continue to
get to the engine by bypassing the throttle butterfly.  Unfortunately,
this also slows engine deceleration, so you lose some engine braking. 
This is even more apparent when you rev the engine in neutral, as the
engine rpm comes down a bit more slowly than I would like (and it
becomes more annoying when you add a third carb, since there are now
three bypass valves working).  Blocking off the bypass valves will have
no impact on anything other than "overrun" situations.  I have not
experienced the "popping" that may occur by blocking off the bypass
valve.

Tim Holbrook
1971 TR6


--- Gary Fluke <res0s0t7@verizon.net> wrote:
> Listers,
> 
> Now I have discovered that each of the bypass valves on my Z-S carbs
> have been
> blocked off by the placing of a solid gasket between the valve and
> the carb
> body.  The rebuild instructions say the valves are there to stop
> exhaust
> popping when backing off the throttle at high RPM.  I don't recall
> any
> popping.  Does anyone have thoughts, pro or con, about blocking off
> the
> valve?
> 
> 
> Gary
> '73


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