[pre-xk] MKV air cleaner

Hi there,

How does one get this can of worms to open?

I am taking about the black cannister with steel wire wool
in the other end. I have the bolt off the other end, but
neither of the ending seem to come off. The one that had the
bolt can be rotated but, not pulled open, and the air intake
end will not even rotate. Should it come off easily or do
the edges need to bent open? I hope not!

Cheers,
Pekka T. - 647194–
MK 5 3.5L DHC, E-type 2+2 Ser.1, XJ6C Manual, XJ8 Executive
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In reply to a message from ptelivuo sent Mon 14 Jul 2008:

This cannister has little inside to be worth opening it up. It is
an air silencer and does not perform any filtering/cleaning except
to keep birds out. It is used to remove the hissing sound from
unsilenced carbs and an on some variations it also has a hole in it
to permit the introduction of excess pressurized gases blown below
the rocker cover to get into the fuel/air stream. It basically is
empty inside except for the metal. Having said that, I don’t know
how to open it. Since there are no replaceable parts inside, it
seems perhaps to have been built without opening capability.–
Roger McWilliams
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If you were to run your engine in my backyard in May/June, it would also
keep out cottonwood and dandelion seeds. You can dribble some oil on the
mesh, and then it will capture some of the dust, but then you have to clean
it every so often.
All you can really do to clean it is swish it around in a bucket of your
favorite cleaning solution. And it is indeed an early form of positive
crankcase ventilation and hence an air pollution reducer, Having said that,
I should mention there is a drain hole in the cast aluminum air cleaner
manifold to drain out all the oil that accumulates in there due to the PCV
action.
Rob Reilly - 627933> This cannister has little inside to be worth opening it up. It is

an air silencer and does not perform any filtering/cleaning except
to keep birds out. It is used to remove the hissing sound from
unsilenced carbs and an on some variations it also has a hole in it
to permit the introduction of excess pressurized gases blown below
the rocker cover to get into the fuel/air stream. It basically is
empty inside except for the metal. Having said that, I don’t know
how to open it. Since there are no replaceable parts inside, it
seems perhaps to have been built without opening capability.

In reply to a message from R_and_J_Reilly sent Tue 15 Jul 2008:

Thanks everyone for your input. I wasn’t going to open it
for cleaning, and was aware that it’s full of, well air,
but mine has a couple of dents and one hole and needs some
paint, so I thought it would be easier to bang the dents out
from the inside.

Also the wire mesh is ok and I know that with oil it will
catch most organic stuff flying around and some dust as
well, that should be enough for me. Also mine being 3 1/2
litre I have the breather hole in the rocker cover so I
don’t want to start customizing this car…rather return it
to the way it was built.

Cheers,
Pekka T. - 647194–
The original message included these comments:

If you were to run your engine in my backyard in May/June, it would also
keep out cottonwood and dandelion seeds. You can dribble some oil on the
mesh, and then it will capture some of the dust, but then you have to clean
it every so often.
Rob Reilly - 627933


MK 5 3.5L DHC, E-type 2+2 Ser.1, XJ6C Manual, XJ8 Executive
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Having recently completed our restoration, I have completed 450 miles of running in. The carb needles are FW as per the book, and new ones. The car is running too rich, with the CO escalating to over 5 at 2,000rpm.
After a long run on the highway, the plugs are black.
We removed the air filter/silencer assembly, and the car is pulling MUCH better, and the CO mixtures are much better. The plugs also have a nice light brown on the tips.
Any tips on improving the airflow within the standard air box? I am thinking of adding some extra vent holes underneath at the rear, covered with mesh.

Frankly I’m surprised that you found a difference with and without the filter. I didn’t think the mesh was all that much of a restriction. Are you sure you cleaned it out really thoroughly? Maybe there’s a mouse or insect nest inside there.

HI everyone, some further feedback on the Mk5 air filter.

  • engine was running far too rich with the standard needles and the aircleaner.
  • we removed the aircleaner, and went for a long highway drive, and not only does the car perform much better, but the plugs cleared and developed the correct clean/light brown grey colour and the fouling disappeared

To research this in more detail, a friend in the car club runs a carburettor repair business, and has a fairly sophisticated gas flow bench.

  • first we measured the air filter airflow, which reflected appalling results, There is a huge discrepancy on air flow efficiency;
  • then we airflowed the aluminum carb intake horn - not great, until we radiused the aluminium corners where the air turns 90 deg into the carbs - this made a noticeable improvement to airlfow efficiency
  • we removed the mesh from the airfilter, expecting a big improvement, and there was no improvement!
  • we then inspected the internals, and there is a very long air horn inside the filter assemble. This requires the air to be sucked in via the mesh, turn 90 degrees into the internal air horn, travel the length of the air filter housing, then turn 180 degrees back half the length, then turn 90 degrees into the aluminium carb/air filter housing. This is a BIG impediment to airflow efficiency.
  • adding to this, the trumpet shape entrance of the air horn, behind the mesh, is much too close to the end of the housing.

The entire air box design is an airflow horror. We have therefore modified it as follows:

  • the radiator end of the airbox we cut out three additional holes, underneath so you cant see them, using the same shapes as the mesh end;
  • inside the filter, we used a hole saw to open as big a hole as possible in the trumpet tube, opposite the carb intake elbow.

The results are astounding. air flow efficiency nearly doubled. The engine now runs happily on the standard needles, and performance has improved noticeably.

The simplest solution to this would be to buy 2 x K&N pancake air filters for normal use, and only fit the standard air filter when going to a car show! Just ensure you buy decent pancake filters that have a deep air filter element - not the rubbish aftermarket ones that have a very narrow element. You need as big a distance as possible between carb intake and air filter end cover. Airlfow does not like 90 degree bends.

It would be interesting to see some pictures of this modification.

The original intent of this giant air cleaner was as a silencer to reduce air flow noise. I’ve seen it referred to as a Helmholz resonator.

Thats really interesting because when I’ve been tuning my car I have generally been doing this with the air cleaner removed at then when completed I will reinstall the air cleaner.
Perhaps I need to revise my procedure.
Thanks for the heads up.
Regards, Graham

Hi Graham,

I wonder if you were to drive the car a short distance without the Helmholz Resonator (love that name!) you would notice any difference in power output?

I you were to fit some pancake air filters similar to those on an XK120, what would do with breather hole in the rocker cover aside from fit one from a 3.5 MKIV? You’d have oil everywhere otherwise.

I have question about timing, which will influence the mixture. With no timing marks aside from those on the flywheel, do you just drive the car advancing the timing until it ‘pinks’ then bring it back until it stops? I’d be interested to hear people’s thoughts.

Tim

I think that cars without any form of intake silencing sound more rorty so you might convince yourself that it’s more powerful but in reality any difference would be difficult to assess without a dynamometer.

Peter

I’ve not noticed a power or torque difference with air silencer off compare to on.

I have noticed the intake noise is much louder with air silencer off, I prefer it on.

For timing question from Tim, I have installed a pointer near the front crankshaft damper (where a timing light shines easily) and painted degree lines on the damper.

On the other end of this, DKWS will not run properly, unless they HAVE their air silencers on.

Quite so, Peter.

No doubt a dynamometer is the perfect way to set the timing and the mixture at the same time. I might just do that.

Tim

Thank you, Roger.

How many Deg BTDC do you use?

I used to set an old Holden I once owned by having a friend move the distributor back and forth while I listened to the sound of the exhaust. Once it was a smooth and ‘hollow’ sound it was perfect.

Tim

Hello Tim, my Mark V is set up with ignition timing 5 degrees BTDC static. The distributor is stock and the measured mechanical and vacuum advance curves agree with the curve specifications of the Service Manual. For about 20 years I’ve run the car with the least expensive (which is the lowest octane, irrelevant other than price factor) modern gasoline with ethanol from anywhere in Southern California. I stuff a wideband lambda sensor in the exhaust to double check my carb settings every couple of years.

If you want to make a pointer for the timing chain chest attachment and paint the engine damper with degrees, the engine damper has an outer circumference of 63 centimeters which makes 10 degree markings 1.75 cm apart.

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Thank you very much for all that very helpful information, Roger!

Stay safe.

Tim