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Tips
Tips

TR5/TR250 Bypass valve

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poolboy said:
Right...the reason I disable it is because it's emission related only under those rare conditions that it opens.
Disabled, I don't have to bother with the procedure for getting it properly adjusted and the idle will never be affected by a bad adjustment or by the inevitable deterioration of the TBV's diaphragm
BUT if you have a 250 (or a 69) it's important to not only have the TBV properly adjusted but also the Vacuum Control Valve that's mounted and activated by the front carb which must be installed and also properly adjusted.
If you have all that and feel the need for the TBV to function when you use 'engine brake' then do not deactivate it.
Click to expand...
Good reply, thanks. So it adds nothing to performance and might deteriorate it. How do you feel about my approach to disabling it by plugging the vacuum tube . See photo I sent. With that approach it’s easy to reactive or not with 2 simple hose connections.
 
That method relies on the condition of the diaphragm and the spring tension on the valve...but you'll know when one or the other is not right..,,the idle will no longer be controlled entirely by the carb's throttle stop screws... Idle may rise a by couple hundred rpms ....similar to what you'll observe during the initial adjustment procedure.
 
In another area on rebuilding. I’m replacing the thr shafts and seals which are well worn. Do you recommend replacing the throttle return spring as well even if they seem ok?
 
poolboy said:
That method relies on the condition of the diaphragm and the spring tension on the valve...but you'll know when one or the other is not right..,,the idle will no longer be controlled entirely by the carb's throttle stop screws... Idle may rise a by couple hundred rpms ....similar to what you'll observe during the initial adjustment procedure.
Click to expand...
That’s really interesting, because I have trouble maintaining the idle on the car. Maybe that’s the reason. It will be interesting to see if replacing the carbs with these rebuilt ones make a big difference
 
Poolboy, thanks for taking the time to answer my questions. Rebuilding these carbs is a project whether I use them or not. I’ve learned a lot, your help included.
 
Hi everyone. I lost one of the three Phillips head screws in the bypass valve (1972 TR6). Anyone know what size they are and where to get one?
 
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