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Re: Fwd: Burning Rich HElp

To: Paul Osborne <>,
Subject: Re: Fwd: Burning Rich HElp
From: Rocky Frisco <>
Date: Thu, 05 May 2005 14:27:54 -0500
Paul Osborne wrote:

>> X-Sender:
>> Date: Thu, 5 May 2005 09:51:38 -0400
>> To: "S. Allen" <>
>> From: Paul Osborne <>
>> Subject: Burning Rich  HElp
>> Cc: Paul Osborne <>
>> Hello, I'm having a rich running problem with a 74 BGT ,18V desmoged 
>> engine ,HIF  carbs, pertronix ignition,
>> reasent valve job, and new rings. engine has 90K miles runs strong. 
>> Engine starts with no problem warms up,
>> running though it burns rich. Black soot on plugs, same in the exhaust 
>> pipe,and rather high fuel consumtiom.
>> Idle seem ok. Have tried a color tune and seems to be right on. I have 
>> been working on British autos for 40yrs
>> and just can not figure this one out. Any thoughts?????

Some possibilities:

Air leak at manifold-to-head seal or manifold-to-carb causes lean mix at 
idle. Adjusting for proper mix at idle causes too-rich mix at cruising 
speeds where the air leak is less percent of overall volume.

Above could also be caused by missing hose in intake system (vacuum, 
etc.) or split hose or missing plug.

Choke not returning to off position for some reason.

Vibration at cruise causing float needle leakage = too much fuel.

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