[Gmecm] Two '747 problems

[nhromyak at comcast.net]

Can you explain this more?

I have heard of reducing the air ABOVE the injectors, but not below butterflies.

-------------- Original message -------------- 

On the large 78mm throttle bodies (Single MFI not dual TBI) GM putst a small alluminum "wedge" on the underside of some of their butterflys to reduce this effect as the trottles are just opened.
HTH
WOT
----- Original Message ----- 
From: JD 
To: gmecm at diy-efi.org 
Sent: Friday, March 11, 2005 8:24 AM
Subject: [Gmecm] Two '747 problems


In the "good old days", this would sound like too much carb for the engine. Since the 454 Tbi is larger and the manifold most likely has larger passages, do you think that could be the problem. Essentially you have GM's largest TBI on it's smallest V8. When the throttle valve opens, that's alot of air for a 5 liter to swallow. This may not explain the idle as much as the stumble problem. If the butterflys are not closing completely, it might explain the idle, too. Have you removed the cover and set the base idle with the ESC bypass disconnected?
I'm new to the list and probably don't know what I'm talking about, but as an "old" GM tech, that's where I would start.



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Subject: Re: [Gmecm] Two '747 problems
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