I'd have to agree with most of Rocky's suggestions except the pressure
regulator setting. At 1-1/2 lbs. there's a good chance the fuel supply to
the carb would be insufficient at anything over 3,500 rpm or under load at
lower revs. We've found it preferable to set pressure regulators at 2-1/2
lbs (which is still below the level at which SU and Z-S float valves begin
having problems).
However, bear in mind that most automotive fuel pressure regulators are not
exactly scientific instruments. The calibration does not necessarily
correspond exactly to the markings, we've found, so start off by setting at
2-1/2 lbs. If the carb/s still flood, set it lower. If the car begins to
stumble and sputter under load, set it higher. The key thing is to reduce
the 6 or 7 lbs output of a non-original fuel pump to something the carb
float valve can handle.
Lawrie
British Sportscar Center
-----Original Message-----
From: Rocky Frisco <rock@rocky-frisco.com>
To: Steven C. Zabel <stubalub@juno.com>
Cc: mgs@autox.team.net <mgs@autox.team.net>
Date: Wednesday, September 01, 1999 11:13 PM
Subject: Re: Newbee
>Steven C. Zabel wrote:
>
>> I have no idea if the momentary engine failures are due to
>> missing, to a clogged fuel line / dirty tank, or if it's all wrapped up
>> into one big mess.
>
>Here's a few odd little things that can cause similar symptoms, in case
>one might help:
>
>1) Broken wire in distributor. Little braided wire in most Lucas dizzys,
>spotwelded to rotary plate or base-plate. The spotweld can let go or the
>wire break, generally causing spotty ignition and unpredictable
>misfiring. Check all the other connections and make sure they aren't
>hanging by a few strands of wire.
>
>2) Bad fuelpump or rotted fuel hoses. You can usually feel that rotting
>hoses are bad just by squeezing them. They will either be rock-hard or
>squungy. Rock-hard hoses are ready to split, so should be replaced;
>soft, spongy hoses may clog themselves with frayed bits inside even if
>they look good on the outside. A fuelpump can continue to work in some
>circumstances but deliver less fuel than what's needed. This will cause
>a lean mix and might harm the engine if you get P.O.d and continue to
>floor it.
>
>3) Slightly too-rich mixture, caused by bad float needle-valve or too
>high fuel-pump pressure. This can effectively limit the acceleration of
>the engine to a certain rpm, where it starts to get rough. If this is
>the case, petrol will be running out of the top of the guilty carb's
>floatbowl. SU floats don't need more than a pound or so of pressure.
>They require a good flow, but not at high pressure. If you're using an
>aftermarket pump like a Facet, etc. you might need an inline
>fuel-pressure regulator. Most hot-rod and speed shops sell them for
>about US$15. Best set at around 1.5 pounds.
>
>4) Bad coil or coil-related connection. The higher the load, the more
>hi-voltage needed at the plugs to fire the mix. Some bad coils will idle
>an engine, but stumble as soon as you try to drive it. Others will run
>fine if driven by a little old lady, but stumble the first time you
>floor it. If the power fails under-load only, this is an area to check.
>A bad connection anywhere between the battery and the coil can produce
>these same intermittant symptoms, whether it's in the ignition switch or
>a terminal somewhere. Bad high-voltage components can cause similar
>problems, diz cap, plug wires, even oil-and-dust-dirty porcelain on
>plugs in humid weather.
>
>-Rock
>--
>Rocky, JJ Cale Band & Pratchett Books: http://www.rocky-frisco.com
>Rocky's Mini Cooper Page: http://www.geocities.com/MotorCity/6437/
>Mini Books: http://www.geocities.com/MotorCity/6437/rockboox.html
>
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