SSH - I just swapped the M1 in -

I had a vac guage on it this morning - its reading around 13 at 900 rpm, but it does waiver a little beween 10 and 13.

I did the leak test with fluid around the intake flange but it had no effect....

As soon as you blip the throttle, and as the rpms come down, the Vac drops to almost zero and the engine flutters and almost dies.

Because its been so badly behaved at low speed, I assumed it was the low speed circuit -

(I checked all the carb gaskets and this carb ran 12.6 at the track last weekend on an LD340)

Are you saying that the TQ shouldn't be effected by the M1 this badly?