51 IDA on 12a, not PP...
 

I just bought a 85 gs with a 12a and it already has a RB manifold and Holley. Not sure if its a RB 465 or a 600cfm holley. The guy I got the car from bought it as is and didnt know, and from what i'm told... i can bet it's a 600.

So, I have these 51 IDA webers with a IDA 12a manifold... I know a holley 600 is far to large for a stock or street ported 12a. But I have had them run fine with the over sized holley before. So is that to say, I can use my 51 IDA, even know they are to large, and get them to run good until i get get a nice 45 or 48 IDA?

Or is a 51 just so over sized it will never even come close to running right?

It will depend on the chokes you have in the 51. If its a stock port 12a you will
need to have a choke down in the 37-38mm (or whatever increment Weber
chokes come in thats close to that) for decent idle at a reasonable rpm.
Otherwise it will have to idle up high to keep running to get the velocity it
needs due to the size of the weber.

the 51 will work fine, like tj said simply install smaller chokes and it will drive great :)

Agreed. That's one nice thing about the weber carbs, you can change the venturi/chokes to configure the carb to work with pretty much anything.

Now i am pretty new to webers. I have owned a few, but never took them apart. How would I go about swapping out the chokes?

Where would I get the smaller chokes also?

ill check and see if i have some. to remove them, remove the carb top,remove acc pump nozzels, then slide out the aux venturies, then slide out the venturies/chokes. its real easy :) .

Did you ever check to see if you had any?

i found some 37mm :) they are in a 48 IDA i recently acquired. it came off a 12A

Sorry, found another set already. Wasnt sure if you were going to reply. Thanks though.