Newbie Emissions Control question

Hi all,

Had my landy about a year now, a Series 3, 3-bearing, 2.25 petrol with a newish Weber carb (not fitted by me). Engine has always run fine.

Been changing the thermostat and noticed that attached to the the oil filler is the emission control pipe (part no. 574262) that runs around the top of the head and heads in the direction of the carb suddenly stopping, is left open to the air (ie not blocked!). It would appear that the rest of the assembly that attaches to below the carb is missing (part nos. 542410, a diaphragm? et al). Below the base of the carb there appears to be a rubber hose that is blocked by a bolt that corresponds to the rest of assembly.

My question is do I buy the rest of the parts (diaphragm? et al) and attach it to below the base of the carb (for completeness),
OR just block up the oil filler hose (part no. 547968),
OR vent to outside the engine, as seems to be suggested elsewhere?

Pros and Cons if possible please!

Been searching on here but can't seem to find a definitive answer. Bit of a noob and not sure what to do!

Thanks all.

Don't worry the bolt is present on my carb adaptor too. Ignore emissions equipment and just leave the weber getting air through the top and fuel through the side! I believe emissions cr @p was for north America only?

Mine has the emissions control stuff on it. If I'm thinking of the right thing the idea is that any fumes that come out of the breather pipe on top of the engine go back into the pipe going from air filter to carb. The fumes are then re-burned.
I wouldn't bother fitting it if you don't have it.

The emissions control stuff isn't just for the tree-huggers. It has positive benefits for the engine too. On a Landy it's pretty simple, there is a hose from the air intake, manifold (bottom of carb) and oil breather (it's not the filler) and a T-piece. The T-piece has a small restriction to reduce the air loss into the carb.

Basicually it gently sucks the blow-by and evaporative gasses from the engine and burns them along with the normal mix. The arrangement with the T-piece is to stop it sucking too hard on the overrun/at idle.

If you remove it the stuff that would be burnt is more likely to condense in the oil / arround the engine leading to a dirtier engine. Also, as I've found on mine, if you remove it the slight vacuum given by the system will be lost and more pressure will build up in the rocker cover making it leak more than it would otherwise.

The carb is jetted with this in mind so if you remove it you may change the operating conditions a little (it effectively leans out the mixture usually but carbs are of course more complicated than that and I found it has only a slight but funny effect on mine).

If you really want to leave it out the other options are to go for an earlier breather - these have a big slit round them and are freer flowing, or put in a road tube - a tube looped over the engine down to the road, the fast air running under the car provides the "suck"....beware wading!

The reason I put mine back was that it stank the cab out in slow traffic...Landys should smell roughly 80% hot gear oil, 15% engine oil, 5% other: random lost pie/sheep ****/unwashed farmer. Too much engine oil / blow by smell upsets the delicate nose...

On another note - you do not need to use the flying-saucer PCV that BL in their infinite confusion ised.

I refitted the PCV on my truck (because the blow-by on a very good engine still made a mess of the bulkhead).

Line from the cap on the top of the valve cover goes to the neck from the air cleaner - that line is there to provide filtered air to the engine from the top, as the flow is downward in that setup. Line from the bottom of the oil-filler pipe goes to the PCV (I used a small generic one from the local motor factor's) and then a line from the PCV to the port on the bottom of the carburettor base.

Cost me little to rig, and the whole thing keeps the engine bay nice and clean from oil blow-off.

PCV - it's not just for tree-huggers anymore. )

ajr

Dominic, i think the rubber tubing was a fiver, and the PCV valve about the same.

The only thing I didn;t buy was the fitting to connect the tube to the carb base - take the bolt out of it and run along to the hardware store for something that fits, or retap it to BSP or whatever. I just made one to fit whatever the thread was - i don;t recall it at present.

This was really cheap. With the sealed top oil filler all the blow-by is coming out the top in reverse of the way the system should work. This way can be an issue for carburettor icing - had that happen to me a long time ago on my 2.25 petrol - routing the blow-by gases into the intake above the carb can be an issue in the cold and damp.