Thermoquad idling issues
TQs will whistle under some conditions & is quite normal.
With THAT cam in a 340, you are going to need at least 30* of idle timing. It is futile trying to tune the idle cct UNTIL the engine has the correct idle timing.
To get the correct idle timing, you do this 5 min test [ vac adv disconnected ]: engine warmed up, idling [ in gear if auto ], turn dist slowly to advance timing. Idle rpm WILL increase. Once you have the highest rpm, check what the timing is. If it is 32* [ as an example ], then that is what it needs for best idle quality & HIGHEST VACUUM. Use vac adv connected to manifold vac to add the additional timing. You will need an adj VA unit with Allen key fully CW. You may need to fabricate a stop to limit the total amount of VA added.
This is not a Holley [ or clone ], so you don't need a gasket kit if you are careful.
Mixture screws 4 turns out + closing the choke to get the engine to idle means the idle cct is lean.....or you have an air leak. Wouldn't worry about the length of the mixture screws as long as they make a difference when you turn them.
TQs will whistle under some conditions & is quite normal.
With THAT cam in a 340, you are going to need at least 30* of idle timing. It is futile trying to tune the idle cct UNTIL the engine has the correct idle timing.
To get the correct idle timing, you do this 5 min test [ vac adv disconnected ]: engine warmed up, idling [ in gear if auto ], turn dist slowly to advance timing. Idle rpm WILL increase. Once you have the highest rpm, check what the timing is. If it is 32* [ as an example ], then that is what it needs for best idle quality & HIGHEST VACUUM. Use vac adv connected to manifold vac to add the additional timing. You will need an adj VA unit with Allen key fully CW. You may need to fabricate a stop to limit the total amount of VA added.
This is not a Holley [ or clone ], so you don't need a gasket kit if you are careful.
Mixture screws 4 turns out + closing the choke to get the engine to idle means the idle cct is lean.....or you have an air leak. Wouldn't worry about the length of the mixture screws as long as they make a difference when you turn them.
