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Old 09-23-2009, 05:31 PM
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Stentor Stentor is offline
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Join Date: Dec 2006
Cobra Make, Engine: CSX 4000; Shelby aluminum FE with 58mm IDAs
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Quote:
Originally Posted by RodKnock View Post
Stentor, may I ask what made you concerned that the 48's would be too small for your engine. Rokndad a few months back installed Webers on his 482 and I think he's running rich somewhat. I'm not an expert in any of this, but Rokndad's engine was making 640 HP before the Webers and, while I'm not sure, I believe he feels that the 48's are plenty for his engine.

I just have always toyed with the Webers idea, but darn that carb, it's so darn simple and it does such a great job.
Rod,

Based on conversations with various folks (e.g., Inglese, Pierce, Keith Craft) as well as calculations using information and algorithms from a variety of sources, the optimum choke/venturi size for Webers on my 511 ci FE is between 49 and 52. The 48 mm Webers would not accommodate this large of a choke (from what I've been told for a street car it's not practical to go above a 42 choke with 48 mm IDAs--as low-end performance will suffer).

Furthermore, the estimated HP loss from switching from a carb to 48 IDA Webers on my engine ranged from 60 HP to 150 HP (something on which I didn't want to compromise).

The good news is it looks like the 48 IDA FE manifold is going to work just fine with the Berg 58 mm IDAs.

I will keep folks posted.

Stentor
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