I'm not sure your assumption is right or wrong. I can only give this bit
of experience. I have always found that using the recommended normal
needles have always yielded the best overall performance and economy.
These needle are pretty close to each other so it might be nice to
experiment with each set. They're so easy to swap, why not try it?
Regards, Paul
PAsgeirsson@juno.com
On Fri, 11 Dec 1998 16:25:56 +1100 Eriks Skinkis <eriks@netspace.net.au>
writes:
>Would it be fair to assume that "M" would be the better needle for
>more power
>at lower speeds and better fuel economy at higher speeds? Or am I
>looking at
>this too simplisticly?
>
>Eriks.
>
>
>Paul A Asgeirsson wrote:
>
>> About the two sets of needles you have.
>>
>> Assuming that the engine you will be contemplating their use on as a
>1275
>> dual carb model some info is below.
>>
>> There are 16 or 12 steps on each needle with the following
>diameters:
>>
>> STEPS AAC M
>>
>> 1 .089 .089
>> 2 .0855 .0855
>> 3 .0835 .0832
>> 4 .0811 .0808
>> 5 .0788 .0785
>> 6 .0765 .0763
>> 7 .0742 .0745
>> 8 .072 .0726
>> 9 .0698 .0707
>> 10 .0676 .0688
>> 11 .0655 .0669
>> 12 .0631 .065
>> 13 .061
>> 14 .059
>> 15 .057
>> 16 .055
>>
>> Up to step 6, the M provides more fuel due to its smaller diameters.
>> Beyond that it would run leaner.
>>
>> The AAC is listed for the 73-74 Mark III Midget as the standard
>needle
>> with the use of blue springs. There are no weak or rich needles
>listed
>> for those years
>>
>> The M is listed as the rich needle for the 1969 MG1300 or the 1971
>MG1300
>> Mk II, or their corresponding Austin marks, again with blue springs.
>Blue
>> springs are what are used in nearly all Spridgets. It also is
>listed for
>> some engines other than 1275 dual carb jobs, but I don't think that
>info
>> is of any particular use.
>>
>> Paul
>>
>> PAsgeirsson@juno.com
>>
>> On Thu, 10 Dec 1998 10:19:27 +1100 Eriks Skinkis
><eriks@netspace.net.au>
>> writes:
>> >I have two sets of 1.25" SU carb's. Looking at the needles one pair
>> >has
>> >the later type spring loaded needles stamped "AAC" while the other
>> >pair
>> >has the earlier type fixed needles stamped "M".
>> >
>> >Is there much difference between the "AAC" and the "M" needles,
>would
>> >one be better than the other?
>> >
>> >Thanks,
>> >Eriks.
>> >
>> >Midget '70
>> >
>> >
>
>
>
>
>
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