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MG TD TF 1500 - TF Engine Gremlins

Looking for some suggestions re my 1954 TF 1250.

Rebuilt a few years ago and runs like a dream most of the time, but now when running and warmed up it occasionally loses some power, engine seems to rattle (horrible noise) and no response from throttle, then suddenly the engine surges back with power and it runs well again. Original Dizzy n points. I don't really know where to start looking and local enthusiasts have not heard of this problem. Ian
IF Shears

My guess would be the coil. Swap it out for a proven unit. Cheers
Peter TD 5801
P Hehir

Definitely NOT the coil. Have recently replaced with new and problem same as before.
IF Shears

If not the coil -

Next culprit is the cap. Please measure the resistance of the central contact to the coal. If it is more than 10-20 Ohms replace it. If it is okay - replace the high voltage cables.

W_Mueller

sounds like it could be sticking valves. This would account for the rattle.As soon as it happens,go to neutral and switch off. Now check your valve clearances. Had this happen on a mates car earlier this year.
Electrical bugs don't make a noise.
Ray TF2884
Ray Lee

Have you tried a substitute rotor arm? Many of those now available are absolute junk. I had a similar problem and solved it by buying a new cap, rotor arm, leads and plugs from the Distributor Doctor, slightly more expensive than other suppliers but top quality. I also fitted electronic ignition but this was after the original issue had been sorted. This mod is highly recommended.


Jan T
J Targosz

Could possibly a valve is hanging up, which would more than likely cause a rattle in the push rod and rocker area. I had valve issues on a Chevy 400 twice and the noise was very loud. One occurrence was a hanging valve stem and the other was a broken valve spring which popped out the keepers and before I could shut the engine down, in an instant the engine swallowed the valve, which, busted through the piston top and then through the side of the cylinder. PJ
PJ Jennings

Ray

missfire makes very bad noise
W_Mueller

Add the coil to rotor arm and condenser being faulty straight out of the box. The only way to be sure is to use a proven unit, swapping one component at a time. Cheers
Peter TD 5801
P Hehir

Thanks for all the info. Will try suggestions. I do have an electric conversion kit to fit in Dizzy. Interesting that a 70 k run on Sunday (35 each way), but never above about 65KPH had no problem at all. It seems at other times when I put foot down to higher speeds, the problem starts.
IF Shears

Still sounds like a sticky valve. Any mechanical noise (not misfire) and power loss can only be mechanical fault.
The higher revs probably throw the valve out to a point where it sticks.
Shutting off and checking will show this up.

As I said a mate had this earlier this year and I had it after fitting bronze guides with too close a clearance. Only happened at high revs. I could cruise all day at 3000rpm (60 mph with 3.9diff) but bring it up to 3500 and a valve stuck open.
Ray TF 2884
Ray Lee

Sticky valve gets my vote, too!
Brian
ZBMan

This thread was discussed between 12/09/2018 and 17/09/2018

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