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MG MGB Technical - Carb Needles

I have a stock '64 B and I have been chasing an intermitant miss at about 2200 rpm under level throttle - kind of like a buffeting in the wind. I have gone all through the ignition, had the distributor rebuilt, valve adjustments and carb balancing, all to no avail. The timing is spot on, both at idle and at 2200 rpm, so the advance is working properly. From the archives I found a reference to the above condition being caused by a lean condition at speed, with a switch to a richer needle being recommended. I am using the standard MB needle for the HS-4 AUD-52 carbs. Moss sells the needle #5 which it says is a better replacement for the MB, but they also have the #6 which is listed as "rich". Sooo, what is the recommended richer needle?

Thanks - Don
don scott

There is a great free program called "haystack" which searches a needle data base. Type Haystack SU into yuor favourite search engine.
Stan Best

hello i have found that no car is the same,ive been told there is over 70 needles to choose from.the only way to fit the correct needles is to select a number of them and try each one on the rolling road. i asked for the correct needle at aldom automotive and they could not give me exact size.i have just puchased xxx needles because the needles have been grand down to much and as a result my car is running to rich and useing to much petrol .
daren

I tried 6s in my car but they sooted the plugs, I then swapped them for some = to AAA ( recomended by Burlen) These worked fine. When I ran Haystack you could see the diffrenece.
Stan Best

hello i got the needle size wrong .i mean AAA needles normaly used with free flow air filters .
daren

This thread was discussed on 19/02/2007

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.