Hi Al,

 

Here's a clip from I email exchange I had with Tracy a while back. For

me the trick to getting a smooth idle and a balanced mixture between

rotors at high power was to measure the MAP right behind the throttle

body so to minimized the effect of the pulses in the runners.

 

The MAP ports are just downstream from the TB.  The difference is that Tracy’s TB is way out there BEFORE the runners.  Mine are about 5” from the rotor housing, and downstream from what are effectively short runners – the TB barrels.  I guess it could be that there is very short term variations in the MAP readings.

 

Is there a pattern here?  Are all those of us seeing rough low-MAP issues measuring MAP nearer the intake ports?  Let’s see; Rusty, Dave. . . who else?

 

Al