HS4 Carb with AAC needle, Will it fit a 1967 Automatic

I think the HS4 car on the Wolseley automatic was fitted with an AC standard needle (not running well on my car). I have a HS4 with an AAC standard needle in it. Will I be able to use this on the car? I think the HS4 with the AAC is from a later 1970s 998 mini when leyland standardised things?
Any advice is greatly recieved
Greg

sebillba wrote:I think the HS4 car on the Wolseley automatic was fitted with an AC standard needle (not running well on my car). I have a HS4 with an AAC standard needle in it. Will I be able to use this on the car? I think the HS4 with the AAC is from a later 1970s 998 mini when leyland standardised things?
Any advice is greatly recieved
Greg

Hi Greg
I'm no expert on SU Carburetter Needles but I know the Automatic 998cc engine was treated to a larger carb (well certainly on later models) to compensate for the increased automatic transmission losses over the manual box. Having experienced difficulties with needle selection and getting optimum performance and economy, I would recommend giving the car a full service including new air filter and then get it set up on a rolling road. This gives true readings across the rev band and as the car is driving the rollers, simulates real road conditions. A typical rolling road test will set you back about £60.00 but is well worth the money.
You can use a static tune kit but this is only useful for measuring the CO levels at tick-over. This is fine if you know you have the correct needle but as I found out the hard way, can be very misleading and in my case the needle was far too rich when under load at about 3500 rpm. This caused what is known as "bore washing" which as it suggests, washes the upper cylinder oil away from the rings and cylinders due to excessive unburnt petol and causes premature piston ring wear and this can happen in a matter of a hundred miles or so. My engine now needs rebuilding as it consumes nearly as much oil as petrol, having said that, it keeps impatient modern drivers at a decent distance due to the oil burning smell and smoke when driven hard. The Aston Martin DB5 featured in a couple of the earlier James Bond films comes to mind but with no ejector seat or machine guns, possible additions for a later date may be!
Hope this helps.

Andrew

Thanks for the reply Andrew.
I do know the AAC needle is a "Normal " needle as apposed to lean or rich. I was wondering if it was the later replacement/equivelent to the AC "normal" needle that was used in the first HS4.
When it comes to tuning and timing I usually rely on a Vacuum gauge after I have the rpm correct. I have quiet recently done the points , leads, condensor, new coil, oil , air filter. I have been thinking of putting a lumenition electronic ignition to get rid of the dam points!! this will alter the timing etc as well.... A rolling road tune up would be great but looking on the net I cant find a place in Portsmouth that does this service. I will keep looking
My carb has not been looked after , its covered in 42 years of thick muck and needs a rebuild even though its only done 32k. I happened on this other more modern HS4 at a bargin and wondered if I could just swap , set up and tune. Then again it might just be as easy to refurb the original. ...
Oh I must say I have not been converted yet either... to unleaded that is. I felt I would leave it until it was necessary. I use Castrol Valve master and shell higher octane. Not a good choice I know to get a consistant timing and tuning.
Greg

Hi

Just looked through the SU reference data, the AAC needle was not fitted to a mini as standard (but AAG was fitted to some later autos) . It was however fitted to mg midgets on twin HS2's in the mid 70's. The rich needle is M1

Ditto above comments on getting it on a rolling road. There is a lot that can play up in a carb not just the needle - damper pot, wrong damper oil, week spring, air leaks(the butterfly bushes are renound for this), etc, and they all interact. Plus the carb is often blamed for other issues on the engine because it is "easy" to adjust to mask them. And this is assuming the engine is standard, including a paper filter.

If you do manage to find a local rolling road, ask them if they are any good on SUs and if they carry a selection of needles and springs - it saves the engineer try to bodge his way around getting the car to run right

Hope this helps a bit

Gordon

Thanks Gordon
Thanks for the info It also helps a lot. At least I know what I have got now and what needle to change too.
I am going to look for the rolling road tune option. I have heard of a place not far away in Waterlooville.
I have just checked the plugs and it is running rich, ie sooty, and the exhaust looks a bit sooty as well.
Cheers
Greg