quote:Originally posted by PanteraDoug:
It isn't just the height of the carb, you need 48mm clearance over the top of the velocity stack clearance to the deck for proper flow.
IDA's need velocity stacks to help the venturi work properly as the guy at the shop I visited said. IDF carbs do not have the same venturi design and should not need velocity stacks. IDF carbs were made to readily accept air cleaners due to the flat top plate. To get an IDA to accept an air filter, you have to use a velocity stack extension and modify it. Please google a Weber IDF and compare the image with your IDA's. They are different carburetors. If you needed the velocity stack, a standard 4-barrel carb would need it too, right? Yes, the velocity stacks create a nice transition for the air to go into the carb to reduce loss of flow, but I would be surprised to see it make a big difference for the street-going average joe with an air cleaner instead of the velocity stack. Give me an air cleaner & better engine longevity any day in trade for a small percentage of power lost.
quote:
The IDA is about 7" to the top of the velocity stack but I think the main advantage of the IDF is that the manifold is lower then the IDA's.
I held both an IDF and an IDA in my hand yesterday. The IDA is around 1" taller than the IDF. The IDF has a flat top plate, whereas the IDA doesn't. The IDF is 4" tall and the manifold is shorter. The advantage to the IDF is actually the short size, ability to run an air filter without stack adapter, more progression holes for better transition from idle to full throttle, and you can run it under the decklid and engine screen without cutting through the decklid and engine screen.
quote:
You can run the IDA's with a shortened velocity stack and auxiliary venturi like the Cobra Daytona Coupes did. You can get them down to about 6".
IDF's will be shorter, even with velocity stacks.