[Mgs] MGB Carb Qs

[Charley & Peggy Robinson]

Do you suppose the "shiny" air cleaners could be blocking those ports?

CR

On 12/27/2017 2:50 AM, PaulHunt73 via Mgs wrote:
> Opinions below.
>
>     ----- Original Message -----
>     I plan to replace the weber (45DCOE) with HS4s on my 1968 GT.  The
>     needles are bent and a float is missing.  Is it reasonable to
>     expect success by replacing these parts (and maybe jets and float
>     valves), after a good cleaning?  What needles and jets?
>     *Yes.  But if the pistons, covers and dampers have beome
>     mismatched you can still get problems.  Always 0.090" jets on
>     4-cylinder MGBs from the factory.  Needles on North American Mk2
>     18GF engines with AUD265 carbs were FX, and in 1969 on the 18GH
>     engine AUD326 carbs used AAE.  18GK engines in 1971 used AUD465
>     carbs with AAL needles.*
>
>     I have shiny carb air cleaners to use on my 1972 Roadster with
>     HIFs, but when I replace the stock air cleaners, the car bogs and
>     won’t accept the throttle.  Should I change jets?  What jets?
>     *The throughput at idle is so small no air-cleaner should be
>     having any effect at all.  Part of the HS and HIF systems involves
>     two small ports either side and above the main orifice. These
>     ventilate the underside of the piston and allow it to rise when
>     the throttle is opened, and must have a clear passage through any
>     gaskets and filter base-plate into the clean side of the air
>     filter, see here http://www.mgb-stuff.org.uk/sut.htm#3 Still
>     0.090" jets on HIF carbs.*
>     **
>     Should a car start without choking?  Is that a indication of a
>     rich mixture if it does?  I have a car with HS6s that fouls the
>     plugs when I start it and move it in and out of the garage, but
>     don’t drive it.  The car needs choked to start but once started
>     the choke can be relieved immediately.  Do I have a mixture
>     issue?  Do I need a meter?
>     *Unless the ambient temperature is high I would say that all
>     SU-equipped MGBs should need some choke to start.  How much, and
>     for how long, varies from car to car and has to be learned. For
>     example my roadster HS choke can be pushed back half-way
>     immediately it starts, even in cold weather or it floods, whereas
>     the V8 HIFs need full choke for a few seconds after starting and
>     only gradually eased back from there, even in summer.  The plugs
>     are the best indication of rich mixture, but no choke, or some to
>     start then pushed all the way back straight away and it will pull
>     away, does indicate rich mixture to me.*
>
>     PaulH.
>
>
>
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