Morris Minor Owners Club

I've got hold of a K&N air filter for my SU 1 1/4" SU, very nice it is too !

The problem is, can't find out the best way to deal with rocker cover breather which pipes into the standard air filter box - theres no provision for it on a K&N.

Some people say just direct it down to floor - but dribbles oil. Other people say to block it off - but surely the breather is needed to vent crankcase.

Any comments would be most welcome !

Cheers, Marty

Ideally you want the later PCV system. This is taken off the front tappet cover, and leads to the later type carb, that has a connection for the hose. You then just blank off the pipe on the rocker cover. Or you can fit the new style carb and connect the original hose to it, but you get more induction noise that way. Or you can machine a new flange to mount the K&N filter to and fit a pipe connection, which gives you the same crankcase ventilation that you had with the original air cleaner.

The later PCV system has a large collection tube welded to the pipe that comes out of the front tappet cover. I think ESM might do them. They also do snazzy alloy rocker covers, very smart.

MoggyTech wrote:Ideally you want the later PCV system. .....
The later PCV system has a large collection tube welded to the pipe that comes out of the front tappet cover. I think ESM might do them. They also do snazzy alloy rocker covers, very smart.

Ta for that. Can you tell me what 'PCV' is please ? I've not come across that befoe, sounds interesting.

Cheers, Marty

You don't need the cam drive breather - the one on the rocker cover is fine, but DO NOT block it off! Ideally - you want a later carb which has a little brass pipe on the side where that breather will connect. To prevent leaks (and smells) you do want the crankcase to be under some vacuum. So - either delay fitting the K&N thing until you get hold of a later carb, or leave it breathing to atmosphere and risk leaks and smells! You do realise the K&N will be quite a bit noisier, and will release virtually NO extra power from an otherwise standard engine !

marty_ell wrote:

MoggyTech wrote:Ideally you want the later PCV system. .....
The later PCV system has a large collection tube welded to the pipe that comes out of the front tappet cover. I think ESM might do them. They also do snazzy alloy rocker covers, very smart.

Ta for that. Can you tell me what 'PCV' is please ? I've not come across that befoe, sounds interesting.

Cheers, Marty

PVC=Positive Crankcase Ventilation
One thing you may find, is that over time, you get fed up of the extra induction noise you get with non standard air filters. They can also lead to lumpy running, as the air fuel mixture is never quite correct, due to the carb design. Your basicaly increasing the air flow, but unless you tune the engine to match, the extra air does nothing to aid performance.

The minimum tuning, would be to have the head worked to increase the port size and gas flow the ports as well. Better exhaust to get the extra combustion gas out. This means an LCB manifold. Now for the bad news, the A Series engine only has a 3 bearing crank, and tuning tends to lead to main bearing failure.

I've tried a Piper Cross Air cleaner, and a pancake filter, but the car runs better with the standard coopers type paper element filter. So the other filter are now garage ornaments

I had the same problem with where to put the breather pipe so I made an oil catch tank out of an aluminium drinks bottle with a breather filter coming out. I catches the excess oil and lets the engine breath easy. Job done.

But the fumes still escape - and they are carcinogenic! Better by far to have the engine eat it's own fumes - and the negative pressure helps to minimise oil leaks too! Note that fancy air filters only allow extra air to flow at high revs and full throttle - realistically - how often do you do that ? Anything else and a clean paper filter passes all the air the standard engine needs. It's only when the engine has been modified that different filters may be required.

Though it can be far easier to fit a K&N (or whaever) than adapt something to fit, IME - the above is very true though, and be prepared to play with carb needles etc too, but BMC's the man to talk about that

Thanks for the comments !

I'm don't want to alter my Minor too much (and am on a budget anyway), so I've decided to fit the K&N, take the breather down to the road (the old engine leaks a bit of oil anyway, a bit more won't hurt) and give it a try for a while. I'll go as far as changing the carb needle; if I needed anything more expensive I'd give up and go back to the standard paper filter.

Regarding induction noise, its a creaky soft-top, so a bit more noise won't worry me !

The reasons for fitting the K&N: it was cheap ! Also paper filters choke up quite quickly in the dusty area where I live. I'm not looking for more performance.

Cheers again, Marty

Now for the bad news, the A Series engine only has a 3 bearing crank, and tuning tends to lead to main bearing failure.

So is 130 - 150 bhp not enough then MoggyTech as there are quite a few `A` series out there with this sort of performance and reliability.

Kevin wrote:

Now for the bad news, the A Series engine only has a 3 bearing crank, and tuning tends to lead to main bearing failure.

So is 130 - 150 bhp not enough then MoggyTech as there are quite a few `A` series out there with this sort of performance and reliability.

Any A Series pumping out 130-150 BHP will have had high quality tuning work done. Tufridge crank, hardened con rods etc etc. The mains failure is often the result of aggresive top end tuning, with no thought about the bottom end.

TUFTRIDED crank maybe - and the con rods are never 'hardened'. Although granted the early pinch bolt rods are useless - need to use the later circlip or press-fit type. 3 Bearings are not ideal - but it can still make a very powerful motor! There is a 200 bhp 1300 Mini engine - on v high boost of course.