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MG MGB Technical - Will I benefit with new Lucas Sport Coil?

I have a '73B and thinking about replacing the standard Lucas Coil with one of the new Lucas Sport Coils From Moss. As far as I know the coil has never been replaced (car has been in the family since it was about 3). The car runs well and can't complain...Sometimes I think that it should start a little bit better than it does. I have the standard 45D4 distributor with points. At this time I am spending money on too many other things so I don't want to upgrade to electronic right now. The Sport Coil has an output of 40,000V but don't know how it compares with the original.

Is there another one out there for around the same price that might work better? It is priced now at 40 USD

Also, I am not sure if I have a ballasted ignition system or not. (my '73 being stock setup)

Thanks,
Eric
Eric Willis

If it ain't broke.......

Cheapest thing for easier starts is to renew points, plugs, condensor. Free advise, FWIW

Paul
Paul Hanley

Eric-
You'll be able to open up the spark plug gap to .035" and get a fatter spark. I'll make for easier cold weather starting and a somewhat smoother idle while the choke is applied. Don't expect any more power, though.
Steve S.

Eric. The Lucas Sports Coil has the POTENTIAL to produce 40K volts. This does not mean that it is producing such all the time. The standard coil has the potential of producing 20K volts. Des Hammill, in his book "How to Build & Tune Distributor Type Ignition Systems" wrote that the average coil is required to put out about 13K volts to produce a spark at the plugs. When the plug fires, there is no further voltage build up in the coil. Some time ago, I was fortunate to obtain a Sun Engine Analyzer which allows me to read out the firing voltages on the scope screen. My experiments indicate that Hammill's information is accurate. Using NGK BP6ES plugs gapped from .035" to .040", the voltage build up in the coil is being shown as 12-13K volts. With the spark plug boot held about 1/2" from the block, the scope is indicating a build up of about 20K volts to cause a spark.

Thus, I agree with Paul. If your current coil is working, do not replace it. I will go further. I would not, after the results of my tests, again install, or recommend that someone install, a Lucas Sports Coil on anything except, possibly, a full race/rally car. Les
Les Bengtson

Les,

What makes you NOT recommend a Lucas Sports coil? Under "normal" conditions doesn't it perform just the same as a stock coil??

Cheers,
Tim.
Tim Jenner

Tim. The Lucas Sports Coil costs significantly more than a standard coil. My experiments suggest that all you are paying for is the "cool looks" without any real benefit in performance. Moss, which makes a good standard reference, sells the standard coil for about $24 and the Sports Coil for about $40. I have used the Sports Coils on several cars, for many years, believing the hype about increased performance. Now, owning the tools to properly check out these claims, I realize why I never saw any "increased performance" after swapping to the Sports Coil. I have no objection, especially since all of my cars currently are running them, to the use of the Sports Coil. But, I have not been able to document any performance increases for the extra monies spent. Les
Les Bengtson

I've always suspected that one 12v/40kv coil is the same as another as far as the spark plugs are concerned. As long as it fits in your mounting bracket and has the right electrical connectors, couldn't you use a generic 12v/40000v coil from the local auto parts store? Granted it might not have that spiffy gold paint and a Lucas sticker, but it might also not have the Moss price tag on it either.

Would one of you electrical pundits mind commenting on this?

Many thanks.
Matt Kulka

Eric: Go to www.mgcars.org.uk/electrical/coil.html all your questions will be answered.
Robert Novak

Another reason not to use the higher voltage coils is that in damp weather the spark is more likely to find an alternate path to earth. The plug wires and covers require replacement more often to prevent this; but on the other hand, this could be thought of as a reminder to maintain the vehicle
George B.

Thanks for the comments. From what I have seen and read now I think it be best not to spend the money. I may buy a new stock OEM style coil for the only fact that the one I have is old and don't want to wait until the car leaves me stranded when it fails.

Thanks!
Eric Willis

Another thing I wanted to ask since we are on the topic of coils. I have heard through the years that a coil either works or it doesn't without any noticable degregation over time. Does anyone know if this is indeed a true statement?
Eric Willis

what does make a difference is an electronic transistor switch instead of points. (late models came with electronic switching) Longer dwell for more amps/voltage at hi rpm. No changing of timing due to wear of points. Much better reliability etc. Some of the expensive aftermarket systems even permit you to adjust initial timing on the fly.
Barry
Barry Parkinson

pertronix Flame Thrower $29.99 at Eastwood.com plus $8.95 shipping
J.T. Bamford

Eric,

Coils can become heat sensitive over time and operate intermittantly. They also have been know to leak their oil, but I wouldn't change one out just because of age.
George B.

The voltage which is advertised for a coil, is the voltage that it can build up with no spark. The voltage that you can see when the engine is running, is the voltage that is necessary to break the dielectric which is is formed by the electrode gap. The maximum output voltage of the coil has no influence on it.
The maximum output voltage is not the only important parameter for a coil, the energy in millijoules and the spark duration are also important.
Sport coils draw more amps and will wear the points quicker. They should be used with electronic ignitions.
Some valuable information here http://www.centuryperformance.com/timing.asp at chapter What Modifications Can Be Done to Improve My Ignition System?

Jean-Marc Thély

I tried the Lucas Sports coil a while back having heard the plug gap could be widened which might improve reliabiity and power. I had a few breakdown troubles after that which I never had had before. I think the higher voltage potential problably brought out some weak links in the system. Tha car would stop and not restart, burned a plug wire etc. I found after getting it home and letting the car go cold for a day I could get it started again. I've heard that coils can overheat and shut down and I think thats what happened and why the wire burned. I think increasing the plug gap caused the coil to work harder creating more heat and eventually shutting down. I did find a great way to use it though. To the left and down abit from the coil is another tapped hole with a screw in it doing nothing. Using that hole and one of the original holes I mounted Sports coil so I now have two coils side by side...one unused but ready. Since I did this I have not had a failure but have occasionally switched to the alternate just to check it. At any rate I got her scared. I'm back to mabe a hair wider than standard plug gap but not much.
Bob Ekstrand

Eric

To answer the second part of your original question, the stock '73 setup did not have a ballasted coil.

I replaced my points with a Pertronix device, retaining the stock coil, about two years ago with no apparent change in performance. I have not touched it since (naturally no points to check); starting and running has been consistently good.

Regards,

Barry
73B
B.J. Quartermaine

Jean-Marc, The Century Performance Tech Zone is a great reference source with lots of useful information, thanks for bringing it to our attention. Clifton
Clifton Gordon

Hmm, my brother owns a Tr**mph Vitesse. On my recommendation he put the Lumenition Magnetronic ignition system on it. Solved all his starting and running problems. Magic. Then, on somebody else's recommendation, he put a new Lucas Sports Coil on. Less than 500 miles later it went open circuit and took the electronics with it. I refer you to the earlier "if it ain't broke" comment.....
T J C Cuthill

The problem with electronic capacitor discharge systems is that voltage is a max whether or not that much voltage is needed or not to create the spark. Often times the spark will be strong enough to arc in the distributor cap, or from wire to ground resulting in no voltage to the plug. As stated in one of the earlier posts, the wider the plug gap the higher the voltage needed to create a strong spark. The consequent higher voltage will very efficeintly find the weak link in the ignition sysem. A stock coil on an mg is fireing half as many times as a coil in a V8 engine. 5,000 rpm in an mgb would only be stressing the ignition system to the level of 2500 rpm on an 8 cylinder engine. The longer the dwell time (the period the points are closed and the juice flowing to the coil)the more time the coil has to reach a maximun voltage. Transistor systems are an electronic switch which can close instantly and provide, in effect, more dwell time resulting in good voltage output from the coil even at high rpms. They are also more reliable than mechanical points.
An early system called a "dwell extender" that was very cheap ($10) with a single switching diode. It used the mechanical points to open the circuit but electronically instantly closed the circuit. It worked very well and improved spark and the points lasted indefinetly.
I used it for years with a hi performance coil on a modified VW. Later on a modified Triumph GT6. And a 4 cylinder turbo mustang. I used to adjust the points every 10k to 15k miles. With the cheap simple - 1 wire to the coil - system never had to touch the points. I hadn't seen one of these for years, but the other day I was in a tool shop and there was a 1 wire "electronic ignition" for sale for $9.95. I also searched the net and found a couple sites telling how to make one yourself. I've lost the web addresses - sorry. The nice thing was if the system failed - I had one that did - all you had to do was disconnect the one wire and you were back on the road using the stock ignition system.
Barry
Barry Parkinson

This thread was discussed between 27/01/2004 and 01/02/2004

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