I've had serveral Supertigres .60s and .75's, where no matter what I did, the engine would either:

- Transition GREAT but idle very rich.
- Idle GREAT but transition poorly.

And no matter what there was no good in between.

I saw an article about an Avastar ( sp? ) on Sports Flyer Magazine, where the author modified the throttle barrel slightly to cure a similiar complaint.

I did this with my problematic SuperTigres and this cured the problem.

The fix allowed a richer LS needle setting, while letting the engine idle a bit more lean... but curing the transition at the same time.

The fix involved cutting a small half moon shape into the throttle barrel intake body, at the point of maximum closure.

I've done it on three engines thus far which cured their problems.

Strangely I've also had other ST engines that were just fine without the modification.