Morris Minor Owners Club

Our new van has a very sooty exhaust which is leaving black patches on our new block paved drive. Is there a quick fix I can do (I'm waiting for a workshop manual to arrive). Is it running too rich? It does it when warmed up, not just when the chokes on!

Cheers
Chris

Sounds like it's running too rich. Check and adjust your mixture. A colourtune is useful for setting it up, or a garage with an emissions tester.

It may also be burning oil - my traveller does (did) that sooty mark thing last year and it is now very poorly, waiting for an engine transplant.

You DO NOT need a colour tune for a car with an SU carb ! It has a built in mixture setting device - the lift pin. If the idle increases when you lift the pin it's too rich - and if it dies, then it's too weak.

The carb is set via the pin - when the revs increase slightly as the pin is lifted , then the revs . drop = correct setting ??

ps . the pin is underneath the carb . -- front in case you don't know where it is -- the big nut under the carb --- turn up to weaken , down to enrich .
If this is in -accurate , then someone will soon correct it ??
Arfron

The Colourtune is really useful, 'cos you can use it on each cylinder in turn to see if there's a problem with just one of them.

Using the "pin" method gives the "average" setting. If one cylinder is ot ok, you can't set up the mixture correctly.

I noticed that the manifold was loose when I had different mixtures in the cylinders -

Colin

bmcecosse wrote:You DO NOT need a colour tune for a car with an SU carb ! It has a built in mixture setting device - the lift pin. If the idle increases when you lift the pin it's too rich - and if it dies, then it's too weak.

This is exactly true! You do not NEED a colour tune to set an SU as they are very easy to set up and if you are used to the carbs you can set it by eye/ear. However, for an amateur it's EASIER to use a colour tune.

BUT the reason I suggested a colour tune or garage emissions tester is that for someone that is not sure if the black soot out of the back is rich running it might be easier than messing around with the carb. I have seen lots of people muck up setting a carb, so I was trying to be helpful by pointing them in a direction that was the easiest for them. Also the 'pin' method for an amateur can be a bit of a trial as sometimes they can't tell what's happening as it's not a completely foolproof method if you have never done it before. We have had lots of posts on here from people who could not make head nor tail of the 'pin' method.