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MG MGA - Air filter materials

I am really considering making my own filter elements for the Volkes air filter cans on my car. Other than K&N's, I havent' been able to find a Purolator or Fram or other filter that will fit that is readily available.

The K&N's get lots of good press - but also some very poor press on the boards from people who seem to know what's best for an engine - and they are wicked expensive. Moss sells only the K&N it seems, and VB lists their filter elements for $32 USD each??!?

It seems to me that it would be easy to make a disposable filter element from materials used for HVAC filters or the kind of filters that go into an above-the-stove range hood. I was planning to buy a furnace filter and some fine mesh screening and cutting out the pieces myself. For about $20, one furnace filter would supply enough material for about 20 or more filters. My plan was to find a suitable screening material and figure out some kind of gasket for the top and bottom edges. Maybe even potting the tops and bottoms with some kind of rubber caulking.

Has anyone tried this? Or is there an inexpensive reliable source for air filters that I am overlooking?



AJ Mail

Ah ha! Blessed be the archives. I found a mention by one Kris Sorneson of Ontario that the Fram CA77 filter works well. Another web search and, lo and behold, Advance Auto parts carries them! Will have to wait until tomorrow to see if my local AAP has them in stock, or will need to order - but they're only about $6 each.

Other suggestions still welcome, however.


AJ Mail

Wow I'm glad I could be of help. I used the Fram filters for 2 years before switching to the K&N's.
Kris Sorensen

OK - getting obsessed with this a bit. Love the internet! I also found a neat cross-reference for Wix - came up with Wix number 42373 from the Fram CA77. Apparently, there are some who feel that Wix is a much better brand than Fram. There are a lot of auto parts stores around here who carry Wix. These seem to run about $8.00 vs. the $6.00 for the Fram. Still better than $80.00/pair!

The Amsoil part is the same as the Wix.

Some tractor filters that also cross to the Fram (poss. available at the local outdoor power equipment store or your local Tractor Supply...maybe even a big box hardware store...?)

Here are some lawn and garden filter part no's that should fit (typically these are 20HP type OHV multi-cylinder engines). All are approx. 6" OD and about 1-7/8" tall. Teh Kohler is available as a 10-pack for $38.00 online!

GRAVELY 010900
GRAVELY 043954
KOHLER 4708302
KOHLER 235116
KOHLER 235116-S
AJ Mail


Chuck Schaeffer published the following (from the archives) in 1994 - long enough ago that it might bear repeating. Some of the info is the same as what I found, above, but some is new.

Fram CA77
Hastings AF54
Fleetguard AF843
WIX 42373
Donaldson P528231
NAPA 2373 (not a good number)
TEHO 21032
FinnFilter FFA10732
Crosland B1000-41543
Beck/Arnley 042-8128

The best NAPA part I can find is SME 702204, which is a 6" by 1.88" filter (ID is 4.63") - pretty close. They are $7.29 each.
AJ Mail

You do realize that you never have to replace the K&N?

FR Millmore

I used the Hastings filters for a while. Then I had some poor performance issues that turned out to be caused by the front filter being oiled to the point where it was not allowing air to flow freely. The oil was a product of the vent hose from the rocker cover that goes into the front filter. I then changed to K&N filters and have had no problem with them. They do not trap as fine of particles as the paper type of filter but I don't drive in dusty conditions very often anyhow. I probably will not drive the MGA enough in my lifetime to suffer from any ill caused as the result of less that perfect filters.
Ed Bell

Yes, but I don't want to use the K&N's. See archives for reasons not to use them as well as reasons for liking them...not all one-sided, and there is some evidence that the K&N's are not as protective as they are free-flowing (originally designed for racing use). No auto manufacturer today that I am aware of uses K&N's as OEM parts. Why not if they are so good and do all that they claim? I have run K&N filters on many motorcycles and am familiar with them - no huge or even not so huge performance boost that I could see. For my MGA I don't plan on putting on a lot of miles so changing the paper filter once or twice a year (max) is not daunting or budget-busting. Cleaning and re-oiling the K&N's is a PITA, however. Pretty much the same rational behind changing over to a screw-off oil filter. The original cartridge type lasted a long time and did a good job, but was a PITA to change. Your opinion may differ...but there's at least a few folks who might prefer to run a good paper filter.
AJ Mail

Can anyone give me a resource where I can search for filters by dimensions and then obtain a part number?
dominic clancy


if you are after K&Ns check here:


WOW, I posted that in 1994? Who da thunk? I actually remember some of that.

Anyway, in spite of all that cross referencing mumbo jumbo, I actually installed a pair of K&N's last year. I can't say there was a noticable improvement in performance. However, with all the bad press about the K&N's, they have to be much better at filtering than the MGA factory originals.

Just my opinion.


Chuck Schaefer

Hi guys, I fitted K&N filters on my rebuilt 1622 engine and have a lot of intake noise from them. Is this normal and are paper filters quieter?

Andy Preston

K&N were first made for military applications operating in extreme abrasive dust - helicopters etc. in the desert. I've read some of the arguments against K&N, and it is certainly true that some other filters clean the air "better", sometimes starting out less restrictive than K&N but always getting more restrictive as they get dirty. A point that people seem to miss is that K&N actually filter better as they get dirty, without becoming significantly more restrictive. They start out cleaning the air "sufficiently", they get better as they get dirty, and it is practically impossible to make them noticeably restrictive. The chopper/tank guys don't need engines failing OR loosing power, and neither do the off road and dirt track guys, all of whom wind up running with 1/4" or more of dirt on the element. When's the last time you had that on your filters? Excessive, sloppy, and unnecessary cleaning interferes with this, forces dirt into and through the element, and just plain screws it up. Put them on ONE TIME correctly cleaned and oiled and LEAVE THEM ALONE. You are never going to put the kind of use on them they are designed for.

FR Millmore

Just bought a FRAM CA77. It fits the outer plate (just, by cramming) but the inner plate has a pipe sticking through it which fouls the filter. How do we get around this? Kris?
Art Pearse

I ordered the Wix 42373 filters which I picked up today - about $11 US apiece.

They fit well, though a bit tight. Trimming the soft rubber flash from the molding process off of the outer edges helped a bit, but I ended up trimming off a thin ring less than 1/16" thick off of all four outside edges and they then fit really well. They come with the integral wire screen material and look very original.

To make the little cut out to go over the breather pipe (I imagine it would be the same with the Fram) I cut a notch in the bottom rubber leaving just a little bit on the outer edge, then used curved fingernail scissors to trim the paper pleats where they were hitting the pipe. Cut and fit, cut and fit - not wanting to remove more than necessary. It's invisible once installed.

I'll post pics if anyone wants them.

AJ Mail

If you want to have a paper element that will fit behind the original screen filter without showing, try a 4"x2" filter element from your local auto store in the chrome accessories area. I have been using these for years and they work fine. They are the replacement element for a chrome filter unit to fit on a normal (older)American V8. The stores usually only have one in stock at a time so it may take 2 trips. I found one online, here is the link:
The wire element may be slightly loose around the edges, but it doesn't matter because the paper element seals well and protects the engine.
The K&N most likely breathes better, but this looks original and works well for me, and is easy to get.
M. H. Dabney

This thread was discussed between 02/11/2009 and 12/11/2009

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