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MG MGB Technical - SU needle comparison?

I have found my 1800 3 brg MGA roadster is running MME needles in its H4 SUs (mild cam only). Seems to run okay with these - have no idea why they were fitted originally before I acquired the car. They are certainly are a lot richer than standard MGB needles according to the http://www.mintylamb.co.uk/suneedle/ comparison chart - I compared the MME to MB, 5, 6, 21, FX, AAE and AAL needles - I suppose only a rolling road session will resolve?
Mike
Mike Ellsmore

Hi Mike
Merry Christmas
Yeah MME is very rich for an 1800
BUT as you say -- on the rollers
5 or MB for std 1800 and 6 for rich

The MME is very similar to a 6 till half way and then it gets rich
If you had a basically std 1800 with no muffler and running ram tubes no aircleaners in short sharp competition events like motorkahna or maybee hillclimbs you might need them but really they are too heavy I reckon

Where people get caught is when for example we have an mga and fit an 1800 motor and refit the mga carbs which if for example if it was a 1600 would have had no.6 needles std. they (the people) mistakingly think they have to richen it up for the bigger motor and fit something like MME needles BUT in reality the needles have to be leaner on the bigger engine compared to what was correct for the smaller unit because of the suck factor
Your MME needles would be close to correct for a 1275 mini or midget on 1 1/2" carbs or a 1500 mga with open exhaust etc as mentioned above
cheers willy
William Revit

Hi Mike

You could try the blue lighter springs rather than the red std ones and see if it is sharper.

Peter
Peter Burgess Tuning

Is there a problem that needs resolving?

If it's obviously rich then try a 'weaker' needle closer to the original.
Paul Hunt

Strangely enough they were used on competition Mini's. They do look rich though, considerably richer than AAA or ABD's, the rich alternatives for tuned and flowed 1800+ engines. ABD were spot on, on Peter's road with my 1860, tuned engine. (Gas flowed, K&N, 3 branch big bore, mild cam, 3 angle seats).
You never know why people used the items you often find fitted to a car. Often I think it's because "I just had them lying about"t!!!
Allan Reeling

Happy New Year
Peter/Mike/guys
Peter, while your blue spring suggestion has merit for a try and-
While I agree that the lighter blue springs would most likely lean the mixture to somewhere near where it should be and make it more snappy, the end result of full throttle under load will still be rich as the same needle will always give the same result under these conditions,and a needle change is the only thing that would change that situation, would you agree with that-------
willy
William Revit

True Willy but worth an experiment for reference? You do not mention you have a rich missfire though so maybe not quite as bad as the figures show?

Peter
Peter Burgess Tuning

Yep
- it may well have already been tuned and is as you say not as bad as it looks on paper, it could already have blue springs and is fine as is--who knows.
A roller session is probably the best move Mike--
Willy
William Revit

The specs for a G and GA engine are #5 needle or rich #6 with a red spring.

Herb
Herb Adler

This thread was discussed between 30/12/2014 and 01/01/2015

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