48 IDA 3rd progression hole

[louisb]

Needed for street driving? Is this something that I could do or no?

Thanks,

--louis

[Zach Gomulka]

It really does help on the transition, especially on small motors without much torque.

[Jim Ratto]

Needed for street driving? Is this something that I could do or no?

Thanks,

--louis

I only have 2 holes. Once I locked advance in my distributor, car is like silk off idle and into main circuits. Maybe John Rayburn will add his opinion here too. I think his car only has 2 holes.

[John Rayburn]

Some need it , some don't. You have to evaluate it with your own engine. Personaly, I run without it and it is very smooth.

[Fastbrit]

I only have 2 holes.

That's what we heard...

[louisb]

So it sounds like try them without and see if it works.If it doesn't, add them.

Thanks,

--louis

[John Rayburn]

If it doesn't work right off , don't start drilling holes right away. You can tune through the idle air mixture. Buy a set of idle jet holders, size 100's and a set of progressive drill bits. 105, 108, 110, 112, 115, etc. You'll need a pin vice for them. Open the holes to 105, install and reset mixture, drive the car, etc. If needed, go bigger, reinstall.... you get the picture. You can normally tune any flat spot out by doing this, so try it first before drilling the carb bodies. Good luck.

[lawrence]

Good advice, John. I wish I would have heard this a while ago. Many tuners nowadays are very quick to suggest the 3rd hole probably because it takes far less time than doing it the correct way. Next time...

Has anyone ever tried a progression slot instead of holes on IDAs?

[Bruce]

It is not wrong to drill the 3rd hole.  In fact, some of the very last IDAs made in Italy came from the factory with 3 holes.  That is why the idea to drill the 3rd hole is so popular.
If you can make them work with 2 holes, great.  They can also be tuned very well with 3 holes.

[Sarge]

I only have 2 holes.

That's what we heard...

 

If it doesn't work right off , don't start drilling holes right away. You can tune through the idle air mixture. Buy a set of idle jet holders, size 100's and a set of progressive drill bits. 105, 108, 110, 112, 115, etc. You'll need a pin vice for them. Open the holes to 105, install and reset mixture, drive the car, etc. If needed, go bigger, reinstall.... you get the picture. You can normally tune any flat spot out by doing this, so try it first before drilling the carb bodies. Good luck.

John's right on the money, here.  Even with a third progression hole, I downsized the idle air from 120 to 115 and tuned out an annoying hesitation after 6 months of misery.

[louisb]

If it doesn't work right off , don't start drilling holes right away. You can tune through the idle air mixture. Buy a set of idle jet holders, size 100's and a set of progressive drill bits. 105, 108, 110, 112, 115, etc. You'll need a pin vice for them. Open the holes to 105, install and reset mixture, drive the car, etc. If needed, go bigger, reinstall.... you get the picture. You can normally tune any flat spot out by doing this, so try it first before drilling the carb bodies. Good luck.

Thanks for the info. I am not quite at the point where I need to tune them. (Unless I can figure out how to mount them on my 1500 sp   ) Was just asking in case I need to send them out to have it done. I will wait to do anything until I get the engine together and in the car. At that point I will probably have lots of tuning questions.

Speaking of any good reference manuals or tuning guides out there for these carbs?

Thanks,

--louis

[Lids]

http://www.aircooled.net/gnrlsite/resource/articles/48idarebuild.htm

[louisb]

Thanks lids. I have that article in the VWT issue and was reading it last night. Oddly enough, the  carbs I am buying are off a car that appeared two issues earlier in VWT April 01.  So my carbs will have been in a magazine even though my car has not. lol

--louis

[lawrence]

Louis, I have both of these manuals and they are good reference material. I got the weber tech manual at cb performance and the weber tuning manual at aircooled.net, but im sure they are available most places. Amazon.com, maybe?

[louisb]

Thanks, I will look into them.

--louis

[banditina]

i think my IDAs made in Italy came from the factory with 3 holes...




www.stinkingass.blogspot.com

[louisb]

On some of the later carbs they added the third hole from the factory.

--louis