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MG TD TF 1500 - Ignition Troubleshooting

Hi all,

Trying to nail down some issues with 1951 TD having trouble starting, rough idle until warm, and missing when hot.

I already have carbs covered I think, did master rebuild kit, new jet bearing kit, and new needles.

Put in new plugs, points, and rotor.

Only thing I haven't replaced is the coil, and I don't know anything about them. First off, ballast or non ballast? Also, my dizzy has "acorn" screw on adapters and the coils I've seen have no threads so use some kind of push in wire, is there an adapter for that? Aside from the seemingly overpriced coils on Moss, what are models that will work? They seem to all be pretty much the same, 12v 3ohm $13 on the cheap side. Is spending another $20 worth it for something like the pertronix coil?

Timing seems to be good, if still runs rough after hot with new coil could be it something more severe like internal engine?

STeve
SD Denham

Valve clearance, failing condenser, bad spark plug wires, improper float setting in the carbs, air leak at carbs or intake manifold?

Tim
Timothy Burchfield

I'd put my money on a bad condenser.

Tom Lange
MGT Repair
t lange

Most new condensers are junk straight out of the box. And the reputation of the AM coils ain't much better. This can make fault finding by replacement very frustrating. Cheers
Peter TD 5801
P Hehir

Agree. Change the condenser even if it is new. Start there.
Bruce Cunha

Thanks, forgot to mention I did also replace condensor, I'm using a 1978 Plymouth Arrow type that was suggested in another thread on this site, due to the ease of obtaining and low cost. I'll spend some time with it tomorrow and let you know what I find.
SD Denham

You need a non ballast 12V coil. The more expensive ones won't make any difference to a std engine. Terminals can be screw type (original) or Lucas blade type, and yes there is a matching blade type socket. Timing generally needs to be advanced a little from TDC static. 5degrees BTDC static should be fine. Are all connections good and the carbs properly balanced with fuel level set correctly?
Dave H
Dave Hill

Hi Steve,

I recommended the Plymoth Arrow consenser in other threads because the mounting "ear" can be attached to the breaker plate in my TF distributor without modification. As noted, modern condensers are a crap shoot. Buy extras.

This coil from British Parts Northwest has screw-in HT terminal. (#GCL101) $22.00 Works for me.
https://www.bpnorthwest.com/ignition-coil-w-screw-in-ht-lead.html

A Lucas Coil foil decal from most suppliers will complete the "look" of a later T-series coil. (The model number listed on the decal is wrong, but few observers will notice.)
https://mossmotors.com/lucas-coil-decal

Check your fuel lines, filters, float bowl, and tank for sediment, rust, and crud that could be retarding fuel flow.

I feel that one of the most common undiagnosed problems in T-cars is the distributor ... after 60+ years of spinning, it's worn out. Not only worn bushes and worn gears, but the pot-metal head of the distributor may come loose from the steel outer shaft. A wobbly rotor will indicate worn bushes. A wobbly head will indicate that it has come loose from the outer shaft. Both conditions will causet the point gap to vary widely.

The advance may be wrong or frozen. The weights and springs for the advance may be incorrect, lost, stretched, or wrong for modern gas.

If the flashes of a timing light are not consistent, then suspect bad distributor components,

Turn the distributor shaft to see if it is perpendicular and concentric to the breaker plate. The plate can be slightly bent to make it perpendicular. If not perpendicular, the rub block on the points will wear faster and will close up the point gap.

John Twist and some others recommend using a dial-back timing light. Run the engine at 3000RPM and adjust the timing to 32-deg BTDC. Don't laugh ... my car runs warmer at speed if the timing is advanced or retarded too much, so I use the temp gauge to tweak timing a few degrees.

Even though I listed this last, it should be the first thing that you do:

Do a complete tune-up and don't skip any steps. This two part tune-up by Skip Burns is one of the best:

> MG T-Series: How To Do A Complete Engine Tune-Up, Part I by Skip Burns
http://www.chicagolandmgclub.com/techtips/mgt/tune_up1.html

> MG T-Series: How To Do A Complete Engine Tune-Up, Part II by Skip Burns
http://www.chicagolandmgclub.com/techtips/mgt/tune_up2.html

Lonnie
TF7211
LM Cook

Moss has reproduction Q12 coil with screw HT terminal for your TD $75:
http://mossmotors.com/coil-screw-type-h-t-connection

Same coil on sale at Moss Europe
http://www.moss-europe.co.uk/ignition-coil-reproduction-of-original-q12-143-210.html

Lonnie
TF7211
LM Cook

The best way to adjust the timing is with a light, 32' at 3,500 rpm, then drive the car, floor it in third gear and wind the engine up to 4,000. If the transmission is quiet, you are there. If the transmission sounds like it is coming apart, retard the timing until it is quiet with this test.
D. Sander

Considering the unreliability of modern condensers, I mounted mine external to the distributor for ease of frequent replacement. I don't think the electrons mind the few extra inches of travel. In addition, since changing to the external mounted condenser, I haven't had a condenser failure. Murphey's law will strike me down for writing that.

Jud
J. K. Chapin

All,

There is no longer any need to live with poor quality condensers you can get good ones from here.

http://www.distributordoctor.com/new_parts_available.html

John
J Scragg

Ihad problem with a new condenser after 1 or 2 miles.
I had problem with a brnad new coil from Moss.

I'm now running an NOS condenser and a NOS coil.
One of each for spare also. No problem.
Check the coil for tightness. It should also be heavy and no oil noise when tilting.

Laurent.
LC Laurent31

Hi Laurent, what do you mean checking the coil for "tightness"?
SD Denham

I have posted some of this before, so please forgive the redundancy.

My original Lucas coil died in 1968, when I lived in Florida.

I replaced it with a $2 coile rom the nearest parts store.

After a 45 year long rebuild I purchased a Lucas Performance Coil, just to get the name Lucas. It had a push-in HT connection.
I decided to make an adapter. This converts the pusn-in to a screw on.

If you have access to a lathe you can make one.

I can post drawings.
I would not use 6 slots again. 4 are adequate.

Jim B.



JA Benjamin

Re the distributor head coming loose from the shaft, they can be sneaky. Mine drove my distributor man mad until we found that it was tight cold, but loosened up when it was hot. He now makes a point of heating distributors before checking for looseness.

David
D A Provan

I agree with D A Proven’s comments about distributor fit and wear issues. Also check for wear in the distributor shaft bearings. My distributor fires in an inconsistant manner due to shaft bearing wear, leading to rough running when at hot idle.

Ian
mgtf 1500 9194
MGTF 1500 9194

For those of you with Distributor problems do yourself a favour and google Advance Distributors. Simply the best. Both of my T-Series cars have rebuilt Distributors done by Jeff at Advance Distributors and they run like new. The best $150.00 +- you will ever spend.
It’s Nike time, just do it.
gl rombough

I mean the coil should not be dripping oil.
Mine was very oily when I bought it but the seller told me there was a leaky one in the parcel. He may be right but the leaky one was the one I bought !
Heavy, no oil noise and no oil leak. To sum up, it should be full of oil. Not half full.

Laurent.
LC Laurent31

Jeff also has good condensers and point sets.
Bruce Cunha

This thread was discussed between 04/04/2018 and 10/04/2018

MG TD TF 1500 index

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