Sooty Plugs

G

georgecook

Member
My 200TC has been off the road for sometime but managed to pass its first MOT under my care last week. At idle the engine is erratic and "lumpy" but at higher revs seems smooth enough. After say 20 minutes running in the garage with the first half minute on choke and several blips on the revs all four plugs become very very sooty. When trying to weaken the mixture the engine hesitates and then cuts out. Would appreciate any comments members may have
My compression are not brilliant at 160psi. 155psi. 150psi and 155psi.Have changed plug leads and plugs my dizzy is electronic, the timing checked on number one cylinder at 6 degrees ATDC. The valve timing is spot on and have today changed carb needles... I just have a feeling that I'm missing something obvious...georgecook
 
I would recommend driving on a good long run. Your compressions are very even, within 10 psi, that is what is important. Did you test with the throttle wide open? My experience with the 4 cylinder motor is that if the motor has sat then it will run rough for a while. Go drive a few hundred miles, and then the motor idles better and overall runs better. One time I drove my Rover 2000 automatic in Adelaide on a 1200 mile trip, to Stanthorpe Queensland, to a Rover event. It idled and ran noticeable better after a few days driving. That was after the car had sat with almost no usage for 2 years.

Has your motor ever been rebuilt? It could have been rebuilt with 9:1 CR pistons. This would explain the compressions being around 150 - 160 psi. I also suspect that starter motor condition can result in lower compression numbers than the 190 psi in the book. Slower cranking causing slower compression numbers. Hence even compression numbers is what I look for.

What plugs are you using? Rover did change their recommendation for that motor from N6Y to N7Y at some stage due to plug fouling issues. N7Y being a hotter plug.

James.
 
Could just be a side effect of the oversized HD8/HS8 carbs? Makes it very difficult to get a consistent state of tune at low revs....?
 
My plugs are new N7Y..I intended to take her out for a longer drive over the last few days, but am still a little concerned about reliability. It has never stopped raining either, and I don't want her to get wet..regards georgecook
 
Took her for a short run, around ten miles and then checked the plugs again. The front two were certainly less sooty than previously and the rear two just the same, very sooty.. This would seem to indicate that the rear carb is running too rich. When idling It still sound like a really rough old diesel.Weakening the mixture makes it very lumpy prior to it cutting out..Not sure what to try next... Maybe that good long run is what is required....georgecook
 
Sounds to me like you need to get the carbs balanced and then the mixture adjusted correctly. You cant do it without the right tools, so take it to someone who knows about carbs.
 
georgecook said:
the timing checked on number one cylinder at 6 degrees ATDC
Click to expand...

I saw this, and thought - shouldn't that be BTDC? Ignition timing being that far retarded is bound to cause at least sluggishness.
 
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