H4 SU Carb - needle advice

Discuss mechanical problems here.
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
Post Reply
maxwoods
Minor Friendly
Posts: 23
Joined: Wed Jun 30, 2004 12:52 pm
Location: surrey
MMOC Member: No

H4 SU Carb - needle advice

Post by maxwoods »

Looking for some advice on needle selection.

Have done basic mods to 1098 engine as follows:-

12G206 head (same spec as 12G295) - probably from a cooper S

Skimmed down to 24 CC combustion chambers ( and unleaded seats)

Std moggie exhaust manifold.

Polished Frogeye inlet manifold

straight through exhaust onto 948 midget back box

H4 1.5 SU

This is more or less what Owen Burton suggests, but I am unsure what needle to choose. Existing needle is 'AM', but whilst I am overhauling the carb, perhaps there is a more appropriate needle.

Max
Cam
Moderator
Moderator
Posts: 5109
Joined: Mon May 20, 2002 1:00 am
Location: Stoke-on-Trent, Staffordshire, UK
MMOC Member: No

Post by Cam »

A AAM needle would PROBABLY be a good starting point. You can only REALLY get it spot on with a rolling road though.

If you had a standardish head and a decent exhaust manifold (3 branch) then I would have ne hesitation in recommending the AAM, BUT some of the head gains will be lost thanks to the manifold, so maybe the AAM would be OK after all.

The AAM is a bit richer than the AM at higher RPM.
Jefftav
Minor Addict
Posts: 720
Joined: Fri Mar 28, 2003 9:28 am
Location: Inverness
MMOC Member: No

Post by Jefftav »

Go to w3.burlen.co.uk and look for link to download winsu software. This at least gives a starting point. The guys at the burlen technical dept are also very helpful but remember they will want to sell there products.

The rolling road really is the best way forward and saves time/effort&hassle.

Jeff
Image
Post Reply