# Diference between ad IDA and IDF weber carb?



## .Andrew. (Oct 20, 2008)

I wanna know whats the diference between and IDF and an IDA downdraft Weber Carb. I have a 87 jetta mk2 Coupe and i wanna know wich of those two carbs is the right one for me. i just want to eliminate all the CIS system and throw a weber on it so i can use it as my daily driver.


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## B4S (Apr 16, 2003)

Technically, the IDA is the older version of the IDF. It has 2 progression holes vs. 3 in the IDF, which makes it a bit jumpier on the transition from cruise to WOT. It's physically larger than the IDF as well. Basically, go IDF IMO. Some of the Aircooled guys swear by the IDA, but on a watercooled motor, the extreme top end flow of the IDA isn't needed. The IDF will flow way more air than our little 8vs can use.


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## 16ValveInside (Nov 20, 2004)

B4S said:


> Technically, the IDA is the older version of the IDF. It has 2 progression holes vs. 3 in the IDF, which makes it a bit jumpier on the transition from cruise to WOT. It's physically larger than the IDF as well. Basically, go IDF IMO. Some of the Aircooled guys swear by the IDF, but on a watercooled motor, the extreme top end flow of the IDA isn't needed. The IDF will flow way more air than our little 8vs can use.


I agree, IDF on the watercooled VW, but on the air-cooled, the 48IDA is king (not a stock one of course).:thumbup:


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## B4S (Apr 16, 2003)

Ha, reading my post quoted in yours made me realize I made a mistake, lol. I meant to say that 'some Aircooled guys swear by the IDA', not IDF.


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## .Andrew. (Oct 20, 2008)

Thanks guys! and btw, what size should i get my IDF Weber for my 1.8 8v... 44? 48?


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## B4S (Apr 16, 2003)

44, and even that's a little big IMO. The 48 would be for a CRAZY flowing engine, probably right to the limit of an 8v after massive head work and a wild cam.

Get the 44 and run some 34-36mm chokes .


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## .Andrew. (Oct 20, 2008)

Thanks a lot


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