Twin SU hs2 needles

[Morris Minor 6cwt]

Hi, I have some Su hs2 twin carbs to rebuild and install for a 1098cc.
Can anyone recommend the best size needles to get me started?
Many thanks.

[philthehill]

The carb needles for a standard 1098cc 'A' Series with twin HS2 carbs AUD136F & AUD136R are AN.
The carbs should have a tag attached stating what carbs are fitted i.e. AUD136F.

[Morris Minor 6cwt]

Excellent. Much appreciated. I'll have a look when they arrive in the post, hopefully tomorrow.

[kevin s]

I'm using a 1098cc sprite set up which burlen list as GY needles and blue springs.

[philthehill]

The details I gave above were taken from the Burlen web site and were for a Mk 3 1098cc Austin Healy Sprite 1964 - 1966.

There are other needles quoted for a 1962 - 1963 Austin Healy Sprite Mk 2 with AUD73F & AUD 73R carbs i.e. GY, GC & M.

The type of crankcase breathing system has a determining factor on the carbs/needles used and the way the crankcase fumes enter the engine. Some SU carbs have a crankcase direct vent into the carb body and others do not. Those that do not vent into the carb can vent through a PCV valve attached to the manifold or direct to atmosphere.

So it is important that the carb tag number is used for determining the correct needle and the type of vent system is accounted for.

[svenedin]

The details I gave above were taken from the Burlen web site and were for a Mk 3 1098cc Austin Healy Sprite 1964 - 1966.

There are other needles quoted for a 1962 - 1963 Austin Healy Sprite Mk 2 with AUD73F & AUD 73R carbs i.e. GY, GC & M.

The type of crankcase breathing system has a determining factor on the carbs/needles used and the way the crankcase fumes enter the engine. Some SU carbs have a crankcase direct vent into the carb body and others do not. Those that do not vent into the carb can vent through a PCV valve attached to the manifold or direct to atmosphere.

So it is important that the carb tag number is used for determining the correct needle and the type of vent system is accounted for.

This definitely makes a difference. My Minor is a standard 1098cc (1969) with a single SU HS2 but it is an unusual Minor as the engine number is 10ME (closed circuit engine breathing) and it has a Smiths PCV valve.

After an engine rebuild which included rebuild of the carburettor and distributor I found the fuel mixture became lean at higher engine rpm with a standard AN needle. I took the car for a rolling road tune and the needle was custom profiled. Unfortunately, I don't know whether any of the off the shelf needles would have been suitable because the tuner did not have all of the vast range of needles to hand. What I do know is that the standard rich needle, H6, was far too rich resulting in black smoke. A rolling road isn't needed to determine that degree of too rich!

Stephen

[myoldjalopy]

Yes, the black smoke will tell you. Better than blue smoke though which means its burning oil