IDFs and IDAs

Ron Earp · 10-27-01, 11:00 AM

What is the low-down on differences between Weber IDFs and IDAs? The IDFs are externally different and are easily obtained. From what I can tell the IDFs are slightly more streetable than IDAs, but not period correct for folks using carbs and trying to make a very accurate replica. Also, they might not be any good at high RPM, >6200 RPM for those working at race RPM levels.

Any comments?

Ron

Frank Catt · 10-28-01, 12:35 PM

Ron, we have been using both sets of carbs (IDF & IDAs) and have gained quite a bit of experiance with them. E mail me for further info. Frank Catt

10-31-01, 04:46 AM

I've run 44IDF's on my car for 4 years now. I am just changing to 48IDA's because we encountered one problem with them we couldn't cure. The total length of the inlet tract is too short, causing fuel stand off above the carbs from about 5500 rpm which kills the power curve. The 48IDA's are longer and don't suffer from this problem. It wasn't an issue for street use but is a problem for track use where you are using full throttle a lot more.

Ron Earp · 10-31-01, 07:47 AM

Another fellow mentioned this to me as well, along with a couple that said it was no problem. Question:

What length is the problem? Is it from the butterfy to the intake valve, or is it from the top of the carb all the way through? If the latter it can be solved.

Still, if at full throttle you're getting too much fuel it seems the thing is rich and could be corrected. But, I've not used the IDFs.

Ron

Bill D · 10-31-01, 12:53 PM

Ron

Check out the Ingelese Induction System website. They have a section called "weber-ology 101" which explains the differences between the IDA and IDF, and problems/cures for different situations.

Good luck

Bill D
Los Angeles, CA

[img]images/icons/grin.gif[/img]
http://inglese.com/index.html

Hershal Byrd · 10-31-01, 02:32 PM

Hey Ron,
I heard the rumor that you got the webers instead of the injection. I had the IDF's on my cobra for 6 or 7 years. They are wonderful carbs and really aren't that difficult to setup. They will be just fine on your GT40. Just don't plan on too many trips to high altitude areas. [img]images/icons/grin.gif[/img] They don't like it at all. They suck gas like an Alaskan pipeline and make some of the damndest popping noises you ever heard. [img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]
I had to take them off the cobra because it wouldn't pass emmisions no matter how well they were tuned. I passed the first time with the injection. [img]images/icons/grin.gif[/img]
Now for the good news, they have the most low end torque of any fuel system and they go like stink. With the light wieght GT40 that torque will be awsome. I don't know why but they run better on solid lifters. I had them on a hydraulic at first on my 34 ford. Then I put them on the cobra with the solid cam and lifters. It just seemed to do much better with less engine hesitation and faster revs.
Good luck and learn all you can cause it makes it much easier to set them properly.

Hersh [img]images/icons/smile.gif[/img]

11-04-01, 11:49 AM

I have no experience with Webers carbs but have talked with quite a few that had them on their cars. The Ida's work well but dont like barometric presure changes. The cam you select has a lot to do with how the whole system works. I installed a TWM throttle body fuel injection on my FFR Cobra with a Speedpro sequential computer. I spoke with quite a few people about various things to look out for. With the throttle bodies you have to use a cam with <112 degrees between centerlines. From what I understand if you start going beyond this you will get reverse emulsion (Gas vapor floating above the stacks) which is going to affect the engine at various rpm probably when it is running slowly. When all the intakes are conected together with a single carb the velocity of the air going in the engine prevents this but when you have 8 stacks the velocity and the pulses caused in each stack can really screw things up. I originally wanted the Motec computer but it was too pricey. It's nice to see Roaring Forties uses this computer as I have heard it is the real deal in fuel injection computers. I also believe it will always work better if run sequential so the fuel is injected as the engine is on its intake stroke.