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MG MGA - New Air Filters

My 57 Mga coupe currently is running rich. I could adjust the mixture but I have decided to replace the air filters. I am doing this ,because they are the " origional " ones that came with the car when I bought it back 52 years ago.

My thought is the new oiled air filters will automatically, let the engine run leaner and there will be no carb adjustment needed. The origional carbs were professionally rebuilt and tested on their test engine and shipped to me.

Am I wrong ?

Gordon
Gordon Harrison

Gordon,
a photo of the filters (fitted) might help, as original can have different meanings.

What work or servicing/maintenance have you done on the air filters since the carbs were rebuilt?

Anything unusual about their fitting?
Nigel Atkins

Below is from an early Driver's Handbook (2nd Edition), replacement filter elements and pads sets seem to be still available.





Nigel Atkins

Gordon
It is unique logic, and you may be lucky and find your change of air filters will, by coincidence, solve the rich running. But without wishing to sound rude, yes, it does sound daft.
To some extent, I find the trickiest part of adjusting the mixture of the carbs is removing and replacing the air filters! I have always found that so fiddly that I have changed the way they are attached, to make it simpler.
So what I am saying is once you have the filters off, adjusting the mixture is really not very difficult at all.
If you have not done it, there's loads of instruction on the web, or I am sure people on this site can talk you through it.
By all means change your filters if you need to, or want to. But while you have them off, you should be able to get them tuned easily enough.
Graham V

The new filters are from Moss Motors , felt with wire mesh. Since I have owned the car the origional filters have never been changed, Shame on me ,

The new ones are as per the picture above.
Gordon Harrison

Gordon absolutely no need to fit new filters if you clean and oil the original mesh ones regularly. So no shame on you unless you didn't clean and re-oil them! You might need some new felts top and bottom of the cans and as Graham says the filters are one of the worst jobs to get off and on again. A few years ago I fitted K&N elements into my original cans and these seem to be good and don't need cleaning so often. Barney's site has details of how to fit K&N elements into the cans.
John Francis

I never liked the original air filters. I use K&N. Much better in my opinion.

As an aside, nowadays I balance my carbs and adjust the mixture with the filters in place. I use the SU balancing rods for the former. This prevents any minor differences there may be between the 2 filter assemblies. The only minus is you cannot do the slight raising of the piston as per the instructions in the manual.

Steve
Steve Gyles

Gordon,
dirty air filters and air filter elements will have richer running, if the air filters are still in reasonable condition then just cleaning them could resolve the issue or get you most of the way there and a small adjustment to the mixture.

The filters Moss sell are original type rather than original, you could just replace the elements and felt pads set and keep your original housings, and save a bit of money.

I'm not one to loose sleep over originality, not even the rust is original on my "classic", but original parts can often be better than modern made parts (not that I've any idea about the new filters) fit better and last longer.
Nigel Atkins

Steve. Just curious, why not able to lift the pins under the pistons?
Bruce.
Bruce Mayo

Bruce - Steve just what I was about to say. The lift pins are not all that obvious though. From memory they are on the RHS of the dashpot underneath.
John Francis

I removed the air filters today and started to replace the filters. I figured it was a good time to do a little cleanup in that area and discovered my problem is NOT air filters but the rear card has a stuck choke / jet . Therefore the rich mixture on the rear carb.

So I will repair the problem , replace the filters and watch over the mixture over the next few months. the original filters were not salvageable.

Thanks everyone.
Gordon

Gordon Harrison

Good that you've sorted it. Do remember to - "Reassemble the front element with the corrugations clear of the breather spigot in the main filter case".

And any gaskets have all the holes where they should be - in a rush I fitted a stub stack upside down covering a hole, it doesn't help with running.
Nigel Atkins

Bruce

Memory failure at this end. Forgot those pins. I was thinking of procedure of lifting them with a small screwdriver when the filters are off.

It's a while since I have had the need to mess around with the carbs.

Steve
Steve Gyles

This thread was discussed between 01/07/2022 and 03/07/2022

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