Actually the float bowl is vented through a special vented washer. I think
the MOSS number is 378-060.
The service manual says the fuel level should be about 1/8" below the jet
bridge (suction chamber and piston removed, ignition on and fuel pump
stalled.) It also says that the level can be as much as an additional 1/4"
lower without adverse effects.
That's what I call a precision instrument.
Bill Lawrence
On 1/3/05 2:56 PM, "Blue One Hundred" <international_investor@yahoo.com>
wrote:
> Ben -
>
> The carbs for a stock BN1 are exactly the same as the
> BN2. They are H4 carbs. H4s from other cars may not
> work because they can have different levers, linkages,
> needles and springs.
>
> BN1 H4s do not have overflow tubes on the float
> chambers. They are vented through a little slit in the
> top of the float chamber. I put tubes on them anyway
> just to keep my carbs clean.
>
> Adjusting the float is the same as most other british
> cars.
>
> Regards,
>
> Alan
>
> '53 BN1 '64 BJ8
>
>
> --- Ben Prince <blprince2@comcast.net> wrote:
>
>> I have a recently acquired BN1. The shop manual
>> states that it has twin SU
>> carbs, inclined at 20 degrees. I find no other
>> identification for the carbs.
>>
>> An SU Hayes manual shows the carbs as H4 for the
>> BN2. No mention is made of
>> the BN1. Are the BN1and BN2 carbs are the same
>> H4s? (1-1/2" throat.)
>>
>> I have owned an MG-TF 1500 for many years that has
>> H4 carbs, spec. no. AUC 728
>> The Healey carbs and the MG carbs are not identical,
>> even though both seem to
>> be H4s. Perhaps the Healey carbs have a different
>> spec. no. I'd appreciate
>> clarification.
>>
>> The MG-TF float chambers have vent tubes. I don't
>> see how the BN1 float
>> chambers are vented, if at all. Can someone
>> enlighten? Also, the MG carbs
>> have a "float depressing plunger" (referred to as a
>> diddler) whereas the BN1
>> carbs don't.
>>
>> Also, how does one set the float level on the BN1?
>> On the MG, the fork is
>> bent until it just clears a 3/8" to 7/16" bar. Is
>> this the right clearance
>> for the BN1?
>>
>> Many thanks,
>> Ben
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