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Su Needle Selection


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#1 unburntfuelinthemorning

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Posted 07 September 2019 - 12:11 PM

I need suggestions for a start up needle to use now my engine build's nearing completion.  I'll be dynoing it once it's run in so just need a ballpark needle to get going with.

 

The important specs are:  998 +0.080"; Calver modified 12G202 head with 1.22" inlet valves; 1.3:1 rockers; MG Metro cam; free flowing inlet and exhaust system with a 11/2" SU.

 

Please expain why you suggest a particular needle.



#2 croc7

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Posted 08 September 2019 - 05:34 AM

Call/email KC for his input. He designed the head, will know the specs of the Metro cam and should be able to get you started. Might be a good idea to include your dizzy specs as well.

#3 alex-95

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Posted 08 September 2019 - 02:13 PM

As above might be worth asking KC or another wealth of knowledge is AC Dodd. What dizzy have you got in it and have you had it re-profiled? If not it would be worth sending AC Dodd a message with your spec and compression ratio and he'll be able to re-profile your dizzy to suit your engine spec. He's done one for my 1293 and the profile was spot on.



#4 unburntfuelinthemorning

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Posted 08 September 2019 - 02:49 PM

I'm planning on going to see Peter Baldwin and Lee Deegan after the engine's run in to have the fueling and ignition taken care of properly.  The ignition's fully mappable so I can stick conservative timing values in it initially, just wanted some advice on initial needle selection. 

 

I had this head on my old engine briefly which was otherwise standard and that took an AAL needle.  With the cam and induction/exhaust improvements on this one it's going to need a richer needle.  I don't want to go too rich whilst running in so was thinking of maybe an AAU to richen the top end slightly but that may be too conservative. 



#5 luismx123

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Posted 08 September 2019 - 05:54 PM

I had an aau in my stage 1 998 and that was a touch lean. had to change up to AAA and that worked better

#6 Moke Spider

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Posted 08 September 2019 - 07:09 PM

Find an engine that has a similar expected power curve on the same Carb and that will put you well in the ball park.

 

Or, try WinSU. While not spot on, I've found it acceptably close.



#7 unburntfuelinthemorning

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Posted 08 September 2019 - 10:19 PM

Where is WinSU?  Is it this?

 

https://www.winsu.co.uk/

 

Says it's unavailable.



#8 Moke Spider

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Posted 09 September 2019 - 12:39 AM

Where is WinSU?  Is it this?

 

https://www.winsu.co.uk/

 

Says it's unavailable.

 

Bummer !



#9 gazza82

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Posted 09 September 2019 - 08:44 AM

What about mintylamb .. it's back .. http://www.mintylamb.co.uk/suneedle/



#10 unburntfuelinthemorning

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Posted 09 September 2019 - 08:58 AM

Yes, I've tried Mintylamb, certainly is easier than trying to decipher the SU needle chart!






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