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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