IDA progression holes...

[gizago]

I know most IDA's left the factory with 2 prog holes, and a few with 3, but did they change the position of the holes over the years?? The reason I am asking is that I am about to drill 3rd holes in mine, (Spanish) and had a look on the Art Thraen how to on aircooled.net,( http://www.aircooled.net/gnrlsite/resource/articles/48idarebuild.htm ) and it shows this-

Most IDAs only have 2 progression holes in them, which makes them more "off/on" in operation. Late IDA's had the third hole when new. Here's how the Third Progression Hole Modification will look after it's done! (We are shining a flashlight down the venturi). The top hole is the new one you are adding.


However, mine has the top hole, its the middle/left one thats missing-



So, I guess what I am asking, is do I add the 3rd hole in the left/middle position to match the Art Thraen example??

Cheers, Mat.

[Speed-Randy]

and shops are charging $100 or more to do that, unbelievable. especially when proper jetting eliminates the need for it

[John Rayburn]

X2.

[Jim Ratto]

and shops are charging $100 or more to do that, unbelievable. especially when proper jetting eliminates the need for it

yep

[Bruce]

and shops are charging $100 or more to do that,

Have you ever tried to do it?
 
Placement is critical, and it's not easy to see down that hole while trying to drill.

[Bruce]

However, mine has the top hole, its the middle/left one thats missing-

The hole you think is the top one is the middle one.  The 3rd hole goes above and to the left of that.  It is the vertical spacing between holes you must keep constant.

[gizago]

Cheers for the advice guys. Might wait and see how it drives with just the 2 holes, I've done the enlarged float bowl mod, but it's mainly going to see (hard) road use, and occasional strip action.

[Speed-Randy]

and shops are charging $100 or more to do that,

Have you ever tried to do it?
 
Placement is critical, and it's not easy to see down that hole while trying to drill.

As I said before, jet it properly and you dont need to drill anything

[bluestar]

not necessary to do that...

[Bruce]

and shops are charging $100 or more to do that,

Have you ever tried to do it?
 
Placement is critical, and it's not easy to see down that hole while trying to drill.

As I said before, jet it properly and you dont need to drill anything

My comment wasn't whether the third hole is needed or not, it was a justification of the cost.

[Type1/DVK]

drive and jet it correctly with 2 holes, and if your not happy with it, or transistion, drill the 3rd.