08-24-2012, 04:22 PM
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Senior Club Cobra Member
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Join Date: Nov 1999
Location: Folsom,
CA
Cobra Make, Engine: ERA 623, 427 S/C Cobra. Ford FE 428 Cobra Jet, Ford Nascar TL 4speed - with a touch of raw; "less is more" theme
Posts: 3,887
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Not Ranked
Quote:
Originally Posted by Gaz64
My bet is the carb idle circuit is borderline lean for the engine. It WILL idle, but the transition circuit won't supply enough idle emulsion above idle. With the fuel we have today, the whole carb including the idle circuit needs to be richer.
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EXACTLY. Transition is lean. Also, one other consideration I thought about is the older and earlier ERA Cobras had slightly more restrictive sidepipes too. I believe the newer ones flow a little better. With the slightly more freeflow sidepipes combined with today's standard (non-HP) 750 Holley, and more blended fuel - I'm betting this is the case; too lean. Especially with 70 primary jets he is using today. Most guys here run 850s/950s on our 428+ FE engines here now days and we don't see these problems like we did before using a borderline 750. I think he could make the 750 work though with some tweaks. Or, throw a Quickfuel 850 on it and be done with it.
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Duane
Western States Cobra Group 1998-2016.
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