Symptoms of Over-rich Running

Post by **wanderinstar** » Thu Nov 18, 2004 8:04 pm

Can anybody tell me the symptoms of over rich running. The symptoms I have are that when running under medium to full power, no problem. But when running in slow nose to tail traffic, engine becomes very lumpy and juddery. The problem just seems to be at low revs, as soon as I put my foot down the problem clears.

Any help would be most welcome.

Post by **Cam** » Thu Nov 18, 2004 8:10 pm

Lumpy at low revs, excessive fuel consumtion, black sooty exhaust, 'hunting' noise from engine, black spark plugs, hesitation on acceleration.

Post by **Kevin** » Thu Nov 18, 2004 8:19 pm

Carrying on from Cam take the plugs out and tell us what they look like.

Post by **wanderinstar** » Fri Nov 19, 2004 4:34 pm

The plugs are light brown in colour

Post by **Gareth** » Fri Nov 19, 2004 6:15 pm

Could the tickover be just a little bit low?

Light brown plugs are just as they should be, I believe...

Post by **Willie** » Fri Nov 19, 2004 7:06 pm

The lumpyness could be what's called transmission snatch,i.e.
play in the prop shaft, too much play in the diff unit, engine/gear-
box unit not located securely enough, or the top engine steady bar
incorrectly set (or broken) OR, if the judder only occurs whilst the
clutch is being slipped in crawling traffic perhaps the bottom steady
cable is wrongly set? Too rich a mixture setting? hardly any choke
necessary to start from cold, and,when warmed up a slow rhythmic
'hunting' beat to the tickover. Locate the carb mixture nut and try
turning it UP a couple of flats, if the tickover speed noticeably increases
then it would suggest that the mixture was set too rich. If you weaken
the mixture by raising the nut by too many flats you will find that the
engine tends to stall when you slow down. HOWEVER,as has been
stated, a light brown centre in the spark plugs indicates correct running.

Post by **grainger** » Fri Nov 19, 2004 11:42 pm

hi

if you dont already, give it a tank of optimax with some octane boost ... is your vacuum advance working ?

cheers

gr

Post by **Arfron** » Sat Nov 20, 2004 1:45 pm

I found that the choke lifted the jet unit , but it then stayed down giving an over - rich and very sooty exhaust ( the car had been under-repair for a long time !! ( I managed to free it all eventually ) )

How difficult is it to change the jet unit and maybe the needle -- I know how to clean -out the piston area and dashpot , etc , but I haven't tackled replacing the jet head and nylon fuelpipe , or centring the needle . Is it better to remove the carb ? Any tips would be appreciated

Arfron

Post by **wanderinstar** » Sun Nov 21, 2004 11:29 am

Willie you could have the answer,My bottom steady cable is missing.

Post by **Kevin** » Mon Nov 22, 2004 8:08 am

My bottom steady cable is missing.

Remember when you replace it dont do it up too tight, just enough to have a slight tension otherwise you will cause vibrations if its done up bow tight.

Post by **ColinP** » Mon Nov 22, 2004 8:56 am

Kevin

My bottom steady cable is missing

Nurse - the curtains - Quickly! (cue for Cam's photo album).

wanderinstar

Having just complete the first 500 miles with the new (recon) engine, I spent a little time checking plugs, points, valve clearances etc etc. I also re-set the idle speed from 1300 rpm to about 900 rpm (drops to about 800 with headlights/heater fan switched on).
That seems to have cured a strange loss of power after 3-4 miles travel (engine would die, slowly - pull over to side of road, & restart immediately, run normally).

I concluded (and the rest of the board will pull it to pieces) that the idle speed and the running mixture are interlinked, and the engine was running just too rich as it warmed up. Plug colors were light brown as well...

Colin

Post by **Cam** » Mon Nov 22, 2004 3:58 pm

The idle speed is just determined by a screw which the throttle cam rests on. It's a bit like holding your foot on the accelerator for you! Like you say, it has nothing to do with the mixture.

Post by **d_harris** » Mon Nov 22, 2004 7:14 pm

How many times has that pic appeared on this forum?

Post by **Cam** » Tue Nov 23, 2004 12:22 am

a few...... probably best expressed as powers of 10!

Why? you got a problem with it???

Post by **Chris Morley** » Tue Nov 23, 2004 12:39 am

Oooh.... Fight, fight!

Post by **Cam** » Tue Nov 23, 2004 12:45 am

Touché Chris, touché.............

Post by **Chris Morley** » Tue Nov 23, 2004 1:20 am

he he

Post by **Kevin** » Tue Nov 23, 2004 6:26 am

Dont worry guys Dawn will break soon and the daylight will calm you down

Morris Minor Owners Club