I keep forgetting that the Rochester B has the idle tube permanently pressed-in, and as such, not readily accessible. Since you are able to purchase non-ethanol fuel, probably better to leave this enhancement to when you upgrade to a different brand of carburetor. It can be modified, but why bother, when better carbs are readily available.

Sorry for the confusion.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop