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RE: Carb issue

To: "Steve Johnson" <>
Subject: RE: Carb issue
From: "Councill, David" <>
Date: Sat, 12 Aug 2006 10:40:43 -0600
HIF carbs? Whether its the HIFs or HS carbs, they still use a float/jet
system. This is very much like a toilet bowl where the flow cuts off after the
float reaches a certain height. With the HS carbs, the top of the float bowl
can be removed and the float plus the needle/seat can be inspected and
cleaned. With the HIF carbs, the float bowls are under the carb bodies so its
harder to work on them without removing the carbs.

Although your symptoms could be caused by a fuel pump that is operating at too
high of a pressure, I would start at the float area. I have heard of floats
themselves acquiring a hole such that they no longer float but have never
personally seen this. The float needs to be adjusted to allow fuel to a
certain level in the bowl. The needle/seats should be replaced at some point
although there may be dirt or grit keeping them from sealing. I am mainly
familiar with HS carbs although I have a spare HIF set from my 72B (it is
currently using HS4 carbs from my old 71BGT). With the HS carbs, I have found
the original style needle/valve set works reliably for several years. The
grose jet version, on the other hand, seemed to be more prone to sometimes not
sealing (tapping trick fixes that).

The Haynes manual or the more expensive Bentley manual will give good
instructions on working with the carb float system. The necessary replacement
parts (gasket, needle/valve set) are fairly inexpensive, I think probably
around or under $20 USD from the usual vendors.

David Councill
1967 MGBGT
1972 MGB
1974 Toyota Landcruiser FJ40
2001 Land Rover Discovery SE7


From: on behalf of Steve Johnson
Sent: Sat 8/12/2006 9:19 AM
Subject: Carb issue


My 1973 MGB was driving nicely early in the summer. I parked it for quite a
while in an insulated garage during an extended wet spell. To shorten the
story, electrical components from the coil to plug wires were replaced.
Finally got it running -- barely. It turns out that fuel is constantly pushed
through the carbs to the point that fuel was exiting out the vapor recover
charcoal canister. I had some advice to pull the top of the carbs to see if
the float was stuck. I did that and turned the key on without starting it and
there as a fountain maybe two inches tall. Following that same advice, I
lightly tapped the carb hoping to dislodge something if it was sticking on
float valve. Now there is just quarter inch or so fountain of gas on BOTH
carbs and the fuel is passing out the overflow vapor recovery tube. I'm
looking for suggestion on a solution as I don't think this is suppose to

Thank.   Steve

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