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MG TD TF 1500 - Can't get the engine run smoothly

Hi, I can't get my engine (XPAG TD2) to run smoothly, it runs rough, irregular and it smooks a lot (especially a lot of soot). I change some time ago the timing chain as it was wrongly sdet (14 links each side of the mark, so changed it to 13 before and 15 links after) and than I could get my engine to run better (reached a higher RPM than before). Problem is that it smooks a lot (which he didn't do before) with a lot of soot from the exhaust, and it runs rough. When starting to ride after it has been running stationary, the engine is hesitating and this only improves after driving some miles. There are new spark plugs in the car, new contact points, timing has been set correctly, carbs are synchronised.
Can anyone advise what could be the reason!
Thanks in advance
Dirk
Dirk Roels

Dirk, It sounds like one or both of the carbs are too rich in their mixture. Could be a float needle valve is not closing completely, a piston in the vacuum chamber is not dropping down far enough and letting more fuel in than needed. With the air cleaners off, so you can look in the carb intake, see if both pistons have the same opening when the engine is running. I honestly believe you have a carb problem, but I could be wrong. PJ
Paul J

Since there is a problem with the picture in the WSM of the timing chain, could it be that you have the 13 and 15 links on the wrong side. Meaning that the cam timing is off now worse than it was with 14 links on each side?
Hope I'm wrong.
Cheers,
Bob
Bob Jeffers

The problem Bob J is referring to is that the WSM picture is shown with the engine right side up, while quite often, the home mechanic will have the engine sitting upside down, resting on the nice flat top of the engine without the head being installed. I fell pray to that one time - after that I cured the problem by simply turning the picture upside down when using it as a comparison. Cheers - Dave
David DuBois

Dave, you're not the only one, I did it about 50 yrs ago on my TD engine. Then a few months later had to remove a Ford V8 engine and fix the same problem on another car that someone else had done (and then had to "go home" 800 mi. away before figuring it out).
A W Parker

dirk, i assume your smoke is black not blue or white? others will chime in with good advice.
if the smoke is black that would indicate an unburned fuel charge from either running too rich or an incomplete burn of a proper mixture due to improper valve timing, lash setting, poor valve seating. improper ignition timing or weak spark is also a possible cause of a proper mixture burning incompletely.
if the cause is too rich a mixture and all else is well sorted, possible causes of a too rich mixture are improper float setting, needle valve/seat not sealing, wrong needle-jet combination, needle set wrong in piston, or needle not centered in jet to allow piston to fall. when setting or checking the fuel level, did you check the fuel height at the bridge with the piston and chamber removed?
best of luck. regards, tom
tom peterson

Hi Thanks all for the advice.
The timing chain is corectly set as pictured in the WSM. Also the pistons are moving freely and drop down evenly.
Smoke is indeed black. I tried to move the jet adjuster nut more up, but it stills smokes.
Should I measure the needles? Are there tables to compare, standard they should be ES needles, but what is the diameter?
Thanks,
Dirk Roels

Try this link, Dirk:

http://www.teglerizer.com/suneedledb/index.html
Gene Gillam

dirk, what is the fuel level measured at the bridge? regards, tom
tom peterson

Hi Tom, Don't know exactly what you mean with the fuel hight at the bridge. Is this the fuel hight in the float chamber? If I remove the piston, how should I measure this? Thanks for the advice
Dirk Roels

I measured the needles and compared them with the list Gene mentioned. Measurements seem to be in line with the standard dimensions.
What could be next?
Dirk Roels

Try checking for a vacuum leak around the carbs....
Use a propane bottle (unlit,of course), and with the engine running , at idle, open the propane valve, and allow the gas to circulate around the carbs, at the linkage, and at , and around the manifold....
If your engine speeds up, you found a vacuum leak.
Edward
E.B. Wesson

dirk, if you remove the vacuum chambers and pistons and peer down into the abyss the structure around where the jet needle inserts is the bridge. there is a lot of info in the archives...but essentially what it says is set the fuel level so the fuel sits .120" to .200" below the bridge.
adjusting the float height by actual fuel level at the bridge is much more accurate. regards, tom
tom peterson

This thread was discussed between 10/07/2011 and 14/07/2011

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