3rd progression hole IDA 48

[priobe]

I would like to find out if you guy recommend drilling out the 3rd progession hole on the IDA 48.

Next, has any had this done and by who. I was thinking about having pierce manifold drill out the hole.

Any suggestion?

[Rick Parker]

I too am going to have it done. Pierce is a couple of hours away, I am going to attempt to take them there and have it done without having to leave the carbs there. From what I understand they screw a fixture into the access hole behind the brass plugs and line it up with the existing 2 holes and run a
.9 mm drill through the drill guide fixture. It is imperative to have the holes in the EXACT same location in relation to the throttle plate for each carburetor. This is not a procedure you would want to attempt without the drill guide. It is not a lengthy procedure, just exacting.

[priobe]

Do you know what else is included in this procedure?

[Rick Parker]

As far as I know NOTHING.

[Bill D]

What is the advantage to this mod?

Bill

[priobe]

This Mod is suppose to clear up the transition circuit and make the car more streetable.

[Rick Parker]

It provides a 3rd hole from which fuel can be drawn from while still remaining on the idle circuit as the throttle plate is progresively opened. It keeps the idle circuit in use longer before transitioning to the Main circuit of which the emulsion tubes play a very significant part. One other critical item is the throttle shafts sometimes have to be slightly twisted to "adjust" the throttle plates orientation, so they are precisely syncronized in uncovering the idle progression holes at the exact same rate, if one plate is "Ahead" of the other, progression will not be as smooth.