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MG MGB Technical - Original Air Filter Housings - Necessary??

I have a 1970 mgb roadster that is basically, but not completely original. While I appreciate the work that some spend to bring a car to concours level, I am not an originality freak. Among other things, I have an aluminum valve cover.

When I bought the car, three years ago, it had no air cleaner housings. It has the original twin HS-4 carburetors. A PO had rigged it up to use the original filter elements, but with a simple 1/8" sheet of aluminum on the outboard end of the filters. The original long bolts secure this to carbs. It includes the original aluminum back plates.

My question is this. Is there any real advantage, other than appearance, to using the original housings? The car seems to run well without them. I have thought of using basically the same setup but with a shorter set of filters. I can pick up a set of original housings on eBay or elsewhere for $10-20, but I kind of like the look of the exposed filters.
Paul Noble

Paul N,

The housing are not a requirement. What you have is similar to the setup Bob Munch described (Bob filters). If you open up the head at all and use K & N filters, the housing will now become the most restrictive element in the equation. If I could make any suggestion, it would be to keep them as they are, and replace the filters with K & N's. You may need to richen the jetting slightly, or even go to the next richer needle, but this constitutes almost free HP.

Paul Konkle

Paul-
The only advantage to the OE airfilter housings is that they are quieter than exposed filters. Paul Konkle is correct in saying that they are too restrictive to get the full advantage of the higher flow capabilities of K&N filters. Avoid going with stubby filters as due to their smaller surface area they can actually be more restrictive. In addition, they can also present a problem resulting from their shallow depth. The siamesed port design causes some very powerful shockwaves within the induction system. The greater volume and depth of the ever-popular 6" X 3 1/4" K&N filters disipates these shockwaves quite effectively. Pancake type filters reflect these shockwaves back into the induction system, causing induction pulse problems which will disrupt airflow.
Steve S.

Thanks. Like I said, I like the looks of the exposed filters. Maybe I'll try to find some 1/8 or 3/16" aluminum sheet and make some better looking end caps. The ones the PO made look like they were cut with a hack saw. THe edges are a little jagged. If I try to grind them down, I think the diameter will be too small.

A big, beefy looking plate, polished to match the valve cover would look pretty good, I think. Perhaps I can find a way to incorporate an MG logo.

I just wanted to make sure I wasn't permanently disrupting the air flow or something. I haven't had any trouble getting the mixture or balance right and the car seems to run pretty well.
Paul Noble

You can see the end covers I made for My K & N filters on my 74 at:
http://photos.yahoo.com/flash1929
Click on, "My 74 MGB". The covers are made from 1/8" aluminum
and should be easy to polish. Clifton
Clifton Gordon

Paul, I also made my own end plate, it can be seen on Tony Barnhill's excellent site. http://www.theautoist.com
Click on "The List", then USA, then scroll down to "Texas". The right hand pic shows a partial view. I have a mechanical drawing if you or anyone else would like it.
Ken Lessig

This thread was discussed between 11/02/2002 and 12/02/2002

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