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MG TD TF 1500 - three cylinder running

Hi Guys....I'm in need of a few comments from the collected wisdom! Since I have been driving my TD I've been working through a rich running problem. The car goes fairly well, but always seems a bit rich. I've got the carbs sorted I think and now have discovered that at least part of the time the car is running on three only. Did a compression check today 1,2 and 4 are 125psi number 3 is 115. The plug on number 3 is always sooty. The car, today on acceleration is missing and going up hills was underpowered, this was on about a 150k trip. Not wires, not the plug. Any ideas?
J.D. Hine

J.D.
From the little info you posted, my assessment would be, the engine is pretty healthy, but #3 may have a bit of ring/cylinder issue. Nothing to lose a lot of sleep over. Add a swig of oil down the sparkplug hole and retry your compression test and see what comes up.

While you fine tune your carbs (I, too, am playing with rich carb on supercharged XPAG) have you thought about going to hotter plugs or Platinum?

Have you considered electronic ignition?

Get down to basics, too. Doublecheck your points & plug gaps... originally they were really tight, like (correct me if I'm wrong) something like .010-.012 inch on the points and .020 inch on the plugs. Make sure your battery voltage is up, too. Low voltage yields weak spark. Where's your timing? How much oil in the oil bath air cleaner? Tappet clearances???

Make sure you're not really running lean at times, like check stem to stern for rust in gas circuit. I stuck an O2 sensor on for an air/fuel ratio gauge, and most of the time it is running rich, but sometimes, I swear, the needle & seat stick (on a relatively new SU) or something starves the engine for gas, intermittently. This can happen with 2 fuel pumps cranking away.

Let us know what you find!

live & learn!!
JIM
Jim Northrup

If you're sure only one cylinder is rich, then it is unlikely that it is a carb problem, since one carb feeds two cylinders...
My first thought is that either the dizzy cap is bad on #3, or the plug or plug-wire is bad.
Try swapping plugs, and see if anything changes.
My second thought , is that the intake valve on #3 is sticking, or out of adjustment, and allows more fuel to enter the cylinder....
Edward
E.B. Wesson

Ed and Jim...thanks for your comments. I don't think the plug or wire are bad, I get a strong spark from the wire with it is off and I've changed the plug with no change. I'm going to check the valve setting and the points. I'll check the cap as well. I'll let you know.

Joe
J.D. Hine

I had a similar problem and decided to check the valve adjustment. When I got to #3 exhaust I found that the threads in the rocker were stripped out and that valve was not functioning at all. Replaced the rocker and two years latter all is well.
Bob McLeod TD 5618

This thread was discussed between 12/06/2011 and 14/06/2011

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.