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MG MGB Technical - su airfilter

hi is there any one who can help.last year i fitted new chrome su airfilters and was advised by carb specialist to put thiner needles in the carbs.i have noticed a little increase in power but the car uses alot more fuel.do you think changeing the needles is needed when fitting new airfilters thanks daren
darenparker

When you fit freeer flowing air filters, the car gets more air in. The needles need to be changed for richer (thinner) needles to stop the engine running too lean. It might aid the fuel consumption if the engine is correctly fueled.
dave

thanks for that,im still a little confused what does correctly fueled mean .the car was set up on a rolling road and at the same time i allso had fitted fireball xr 600 electronic ignition and a falcon 3 branch man and ss pipes. the car seems to have a small amount of extra power but not to shure iff it was worth it thanks daren. im getting around 50miles on 10pounds ,do you think thats ok daren
daren parker

Fitting freer-flowing filters and exhaust usually results in a weaker mixture as Dave has said, and usually a richer needle (one that tapers down more rapidly than the standard) should be fitted or you get flat-spots. In itself either shouldn't cause the car to use a 'lot' more fuel, maybe you are just using a heavier foot to take advantage of a minor performance increase?

How much are you paying for fuel? At 90p per litre, for example, that is 11.1 litres or 2.45 gallons, and for 50 miles that is about 20mpg. That is low in my book, but could be explained by a lead foot around town. You should be getting much closer to 30, I get 30+, and have seen 40 on Continental touring.

If it was set up on a rolling road correct carb needles should have been selected and fitted, otherwise what else were you paying for time on a rolling road for? The usual valve, ignition and carb adjustments are much cheaper done at home. Are these correct?
Paul Hunt

Those flat chrome filters or "stellings and hellings" units are no good. They restrict the airflow at higher RPM and choke down the engine. Also, the stock ram in the filter housings are removed so you get flow interruption at the carb mouth.

If you are talking chromed stock housings... Well, why use different needles if you have the same elements in there?

If you changed to a high-flow element then the previous posters comments are appropriate.

Mike!
mike!

You could still probably use your chrome end caps if you did something like Roger Hotelling suggests at his site, http://www.hotelling.com/mgb7.htm . You would have to use the longer stock filters (either the paper or K&N variety) used in the OE Coopers' air filter cans, but you would get much better flow and filtration than with most pancake type filters. I am sure there are other opinions of what should be done, but the setup Roger shows does work well enough to please most folks most of the time. FWIW
Bob Muenchausen

Ja, I did much the same only I used a single piece of scrap aluminum I had laying about.

I must say I'm dissatisfied, however. The underbonnet temps are high enough to kill any advantage. I will be making an air-box next (what, #5,239 on the list?) lol.

Mike!
mike!

This thread was discussed between 05/01/2005 and 11/01/2005

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