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MG MGB GT V8 Factory Originals Technical - holley/carter 390 carb help?

i have a an older 390 4 barrel holley on my mga, sent it in to have it rebuilt, cleaned, and redyed, now i am having a bear of a time tuning it, mostly i think from lack of knowledge on these, not sure if i have vacuum hooked up right, etc, etc. not getting the later 2 barrels to open, does anyone have a manual on these that they could fax me some pages of or maybe send in a pdf? i think the older holleys are the same as the carter? but not for sure, thanks, jim
jim m

The basic secret of carb function is that inside each carb are
thousands of tiny gnomes; each with a small bucket. As you open the
throttle, more of these gnomes are allowed out of their house and
into the float bowl, where they fill the buckets and climb up the
carb's passages to the intake, where they empty their buckets into
the air stream.
But, if you don't drive the car for a while, bad things can happen.
Tiny bats take up residence in the chambers of the carb, and before
long the passages are plugged up with guano. This creates a gnome
traffic jam, and so not enough bucketfuls of fuel can get to the
engine. If it gets bad enough, the gnomes simply give up and go take
a nap. The engine won't run at all at this point. Sometimes you'll
have a single dedicated gnome still on the job, which is why the
car will occasionally fire as the gnome tosses his lone bucket load
down the intake.

There has been some research into using tiny dwarves in modern
carburettors. The advantage is that unlike gnomes, dwarves are miners and
can often re-open a clogged passage. Unfortunately, dwarves have a
natural fear of earthquakes, as any miner should. In recent tests,
the engine vibrations caused the dwarves to evacuate the MGB vehicle and make a beeline for the nearest BMW dealership. Sadly, BMW's are fuel injected and so the poor dwarves
met an unfortunate end in the rollers of a Bosch fuel pump.

Other carb problems can also occur. If the level of fuel in the
float bowl rises too high, it will wipe out the Section 8 gnome
housing in the lower parts of the carb. The more affluent gnomes
build their homes in the diaphragm chamber, and so are unaffected.
This is why the car is said to be "running rich".

If the fuel bowl level drops, then the gnomes have to walk farther
to get a bucketful of fuel. This means less fuel gets to the engine.
because the gnomes get quite a workout from this additional
distance, this condition is known as "running lean".

The use of the device known only as the 'choke' has finally been
banned by PETG (People for the Ethical Treatment of Gnomes) and
replaced by a new carb circuit that simply allows more gnomes to
carry fuel at once when the engine needs to start or warm up. In the
interests of decorum, I prefer not to explain how the 'choke'
operated. You would rather not know anyway.

So, that's how a carburetor works. You may wish to join us here next
week for electricity 101, or "How your car creates cold fusion
inside the starter, and why the government doesn't want you to know
about it." This class can be found under the heading "Never Let the Smoke Out!"
rick ingram

WOW, GImme someof what Rick is on!!!!

Larry Embrey

thanks michel i got the link you sent, thanks rick that explains it, i had been using the wrong gnome coefficent because i had calculated it using an improper variable in the initial inverse equation. see what 4 quarters of college calc will get you? maybe jegawatt can set me straight?
jim m


I shared your explanation of carburetor function with a couple of auto enthusiasts that donít frequent this web site and they ask that I try to get you to elaborate on the choke system. They read as well as I did how you are trying to spare the sensitive, but enquiring minds want to know.

George Champion


you are one sick....


rick ingram

This thread was discussed between 27/08/2004 and 01/09/2004

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