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Which SU needle ?
https://ausmini.com/forums/viewtopic.php?f=5&t=15858		 Page 1 of 1
Author:  ronniemac [ Sat Feb 04, 2006 7:04 pm ]
Post subject:  Which SU needle ?
If using the SU needle program to work out what needle you need it doesn't seem to ask if you have single or twin carbs. If it does then i'm blind.
Does anyone know how to work this out if you have twin 1 1/2" SU's ?
What needles are you people running that have similar engines to mine.
I have a 1275, 12g940 head sligtly ported, quite lumpy cam ( not sure of size ),
S type extractors and 1 3/4" exhaust
Author:  AJ [ Sat Feb 04, 2006 7:28 pm ]
Post subject: 
David Vizards book : Tuning BL's A Series Engine , gives a bit of a guide . A 1275 S with 2 x11/2 SU's + modified head + semi race cam uses red springs and No 3 or 4 needles . A 1275 S with 2x 11/2 SU's + modified head + full race cam + extractors uses blue or red springs and BG needles . Use it as a starting point and have the engine dyno tuned is the best way , take along a few different needles
Author:  drmini in aust [ Sat Feb 04, 2006 9:07 pm ]
Post subject: 
AJ wrote:
David Vizards book : Tuning BL's A Series Engine , gives a bit of a guide . A 1275 S with 2 x11/2 SU's + modified head + semi race cam uses red springs and No 3 or 4 needles . A 1275 S with 2x 11/2 SU's + modified head + full race cam + extractors uses blue or red springs and BG needles . Use it as a starting point and have the engine dyno tuned is the best way , take along a few different needles

MK2 Cooper S in Oz with the Police pack had twin HS4s and Ramflo filters.
Standard needles were CP4.
I find #6 needle is better, A/F ratio is spot on 13:1 all the way up. :wink:
Motor is a 1293A+, Tighe 270* cam, ported head, C/R 9.4:1, Corolla 1.5:1 rockers and Perry 3-1 freeflow manifold.
Author:  ronniemac [ Sat Feb 04, 2006 9:52 pm ]
Post subject: 
Thanks guys,
I will try #6 and see how it goes.
I'm not sure of compression ratio but told not standard and engine bored out to 1310.
Rockers are not standard either. They are solid and about 1/2 " wide and not sure of ratio.
Author:  drmini in aust [ Sun Feb 05, 2006 5:48 am ]
Post subject: 
ronniemac wrote:
Thanks guys,
I will try #6 and see how it goes.
I'm not sure of compression ratio but told not standard and engine bored out to 1310.
Rockers are not standard either. They are solid and about 1/2 " wide and not sure of ratio.

That sounds like the POS later sintered type, used on everything from ~75 on.
They are only around 1.24:1 and don't even have bushes in them.

Best stock factory rockers for a 1310 are the earlier 1275 pressed metal type with oval pads. They are ~1.3:1.
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