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Ignition

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Ignition
#1
  This topic is about my 1952 MG TD
Guy Das Avatar
Beringen, Belgium   BEL
1952 MG TD
2018 Jaguar XE
I am starting the winter maintenance of my TD 16067 - Xpag 16344. One of the items is the ignition. What is the best gap (in mm if possible) for the contactpoints ?
Question 2 : How can I check the condition of both coil and condensor ? Can it be done with a multimeter (AC - DC - Ohm) ? And question 3 : Can both coil and condensor be replaced by a part of an other make of car ? Via a local junckyard I have access to a vast stock of simular parts.

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MG TD 45.JPG

crankjournal Avatar
crankjournal Len Fanelli
Yonkers, NY, USA   USA
Guy, for question #1 you will need to measure from lobe to lobe and or from flat to flat on the distributor cam.
D. DISTRIBUTOR CAMS

The early distributors were fitted with "symmetric" or "asymmetric" cams, these use a point gap setting of 0.010" - 0.012". Dimension across high points of cam lobes is 0.748" and across cam flats is 0.701"

The later "High Lift" cams use a point gap setting of 0.014" - 0.016". Dimensions across the high points of cam lobes is 0.748" and across cam flats is 0.643". These dimensions are my own measurements and not factory numbers. The high lift cam was fitted to later distributors to improve ignition system performance and increase contact life. (Thanks Bob!)

Mikelead Mike Leadbeater
York, Yorks, UK   GBR
1953 MG TD
Why not fit electronic ignition? the engines run so much smoother with it. You won't need a condenser also. Look on eBay, they can be very low cost.

To check the rest of the system you really need an oscilloscope, with a clip-on sensor on the ht lead, available on eBay.

I am looking for a module to provide an oscilloscope input for a laptop or pad, ANYONE KNOW OF SUCH A DEVICE?

Youtube has many posts showing how to use a 'scope for ignition analysis, it can be very revealing of any weaknesses in the system

cheers

Mike

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Buckdendave David Hill
St Neots, Cambridgeshire, UK   GBR
1954 MG TF
Just carry a spare electronic unit with you if you do. I have read of far too many failures in electronic ignition to go down that route. Points work just fine, but for accuracy set them up with a dwell meter.
Dave H



Edited 1 time(s). Last edit at 2019-02-07 07:37 AM by Buckdendave.

crankjournal Avatar
crankjournal Len Fanelli
Yonkers, NY, USA   USA
Every time I used a dwell meter to check my feeler gauge setting of points, I was exactly dead on, from my 1st time about 55 years ago!
Len

Ralph 7h Avatar
Ralph 7h Ralph Siebenhaar
Viersen, Germany   DEU
Guy,

I can only confirm the answers concernig ponts. In the late 1970's and the 1980's, we used a Triac electronic ignition box that took away the tension from the points and these modules worked extremely well. Still use then on my TD and TF.

The coil in your car ia an aftermarked Lucas high output and you should not change it, as Long as it works. just renew the ign. cables and plugs (WITH NEW ONES!) and for peace of mind, carry a Lucas Sports coil in your tool box...

Ralph

TD 19435 & TF 6815

Tpss Tim Parrott
Stroud, gloucestershire, UK   GBR
1938 MG TA
I have a 1970's Analogue strobe light, tacho and dwell meter all in one instrument that works well for timing and calibrating the dashboard Tacho.

My understanding is that the Dwell Angle is the arc that the points stay closed for. It is a function of the points gap and the contours of the distributor shaft.

The points were set by Martin the Distributor Doctor when he rebuilt my Distributor some 1300 miles ago. From memory they need cleaning and checking every 1000 miles. The points gap and the dwell angle will differ if the points are badly pitted which is time to change them anyway.

What value should I be looking for on an MG TA?

On the other hand I just need to record it now or with a new set of points and use it as a condition monitor.

Mikelead Mike Leadbeater
York, Yorks, UK   GBR
1953 MG TD
As you say Dave, electronic units can fail, never had one go myself, but in case I always carry the old points.

Main thing is the engine runs much more smoothly, and no points to adjust.

Available on eBay for around £40, in both positive and negative earth.

Time with a strobe light on the front pulley, highlight the marks with white paint.

MGTF1500 Ardeche France Avatar
MGTF1500 Ardeche France Thierry SUCHIER
TOURNON SUR RHONE, Rhône-Alpes Auvergne, France   FRA
I have never been able to use this lamp on my TF "with a strobe light on the front pulley"
Can not find the place or position correctly without being generated by either the fan or the transverse reinforcement.
Is someone how I should do?
Sincerely, Thierry de l'Ardèche



Edited 1 time(s). Last edit at 2019-02-08 12:58 AM by MGTF1500 Ardeche France.

Buckdendave David Hill
St Neots, Cambridgeshire, UK   GBR
1954 MG TF
You are right that on the TF is is a little difficult because the view is obstructed. However I can manage to do it on my TF with the engine 10mm further forward owing to the 5 speed gearbox. It helps if you put a spot of white paint on the tip of the pointer on the timing cover and on the timing notch on the front pulley.
Dave H

MGTF1500 Ardeche France Avatar
MGTF1500 Ardeche France Thierry SUCHIER
TOURNON SUR RHONE, Rhône-Alpes Auvergne, France   FRA
David, even with the point of white paint on the pulley, I did not get to the point.
Ok, so I'm not clumsy.
Sincerely, Thierry de l'Ardèche, South of France

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