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Discussion Starter #1
Has anybody heard anything about engine cutting out just like you've turned ignition off when the engine gets to a certain tempreture......Its got the old type lucas electonic ignition

and Ive been told that one of the problems is when the tempreture gets to certain level it just shuts down, let it cool down and away it goes again till the temp rises.
1978 Shadow 11


Roger
 

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Discussion Starter #6
Was it changed with one of the same resistance?

Yes I believe so...........We are now fitting a petronix system including coil......The reason for asking is the motor has just started cutting out and there is no spark leave for a few min and it runs again, sometimes you can do 20 ml other times 1ml and every time no spark leave for a few min and it's all back again......When talking to Flying Spares one of the guys there told me that the old type lucas electronic ignition system
used to do that, and I just wondered if anybody had heard of or experienced that problem.
Roger
 

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Changing out the actual ignition should solve your problem.
Don't forget to inspect the rotor and cap for wear.
New wires should also be considered, especially if they are still the original ones.
 

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Roger, where have you determined there is no spark when it dies? If at a spark plug that does not necessarily mean the ignition module is faulty.
First thing to do when it dies is to check for spark at a plug lead, then spark at coil lead. If no spark at plug but spark at coil lead - rotor is faulty. If no spark at plug and no spark at plug lead - coil or module faulty. To determine which, attach a 12 volt test light to negative low tension terminal of coil. Have someone crank over the engine, if light flashes quickly the module is working trying to fire the coil - coil is faulty. If light doesn't flash the ignition module is faulty. These tests are assuming you have confirmed there is power at the positive low tension terminal of the coil.
Also to confirm a rotor is faulty, remove cap, remove coil lead from cap, hold end of coil lead to within an eighth inch of the centre of the rotor with gloves or insulated pliers. Have someone crank over the engine. If the sparks jump to the centre of the rotor the rotor is faulty. A spark SHOULD NOT jump to the rotor if it is good. Rotors can function fine when cold, short out when hot, and have intermittent symptoms. We see faulty rotors fairly often, especially aftermarket ones.

The following is copied from the Distributor Doctor's website: (We Have no affiliation etc.)

"Rotor arm problem

Distributor Doctor can now offer a high quality alternative to the commonly available reproduction rotor arms which have been routinely failing and leaving people stranded.
This has been a sore point for TR owners for almost a decade now, but it also affects a host of other Lucas equipped vehicles from the 1930's onwards.
Recently manufactured rotor arms have been failing because the typical "mix" used in the injection moulding nowadays contains more carbon blacking and is therefore more conductive. Still more importantly, the rivet which holds the brass inlay into the moulding is slightly longer than the original, bringing it too close to the spring clip on the underside. The high tension current, averaging 30,000 volts, is always looking for the easiest route to earth and shorts out from the tip of the overlength rivet, through the reduced thickness of more conductive plastic and the spring clip on the underside of the rotor arm, to earth out down the distributor shaft. Result - no sparks at the plugs. The situation sometimes rectifies itself on cooling, but then reoccurs with increasing frequency until the rotor permanently short circuits.
"
 

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Roger, I should also add that we do see lots of failing Lucas OPUS ignition modules too, not just rotors. They will show the same intermittent symptoms as a failing rotor, runs when cold, dies when hot.
 

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Discussion Starter #10
Update


To all that have replied.....Thank You and those that have read of the problem..........It's now solved apparently the early Lucas Opus electonic ignition is prone to breaking down when it gets hot
We've just fitted a Petronix electronic ignition and a new coil to go with it and it seems to be running okay.........I would suggest anybody that's got the Lucas system fitted change to Petronix
but you must have a coil that goes with it.


Roger
 

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Update


To all that have replied.....Thank You and those that have read of the problem..........It's now solved apparently the early Lucas Opus electonic ignition is prone to breaking down when it gets hot
We've just fitted a Petronix electronic ignition and a new coil to go with it and it seems to be running okay.........I would suggest anybody that's got the Lucas system fitted change to Petronix
but you must have a coil that goes with it.

Roger
My 1974 Shadow is cutting out when hot and stalling, it will only start again about 1 hour later when cold.

Can anybody offer advice and give me the exact model of Pertronix electronic ignition kit that I require, and also the correct model Pertronix coil that I would need, that will hopefully rectify the problem?
 

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First replace your coil with the same spec (ohms) like the original. This may very well cure the non start issue.
The Pertronix model is LU-281.
 

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Having had just this sort of failure, I doubt very much it's the coil, though it's cheap to rule it out. The Lucas Opus is notorious for failing in just the manner described.

Read my saga on the RROC-Australia forum several years ago: A Christmas FTP!! . . .
 

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Opus was introduced on 22673 which is late June 1975.
Inquiry is for a 1974. I would replace the coil and update to the Pertronix ignitor for peace of mind.
After installing one for a recently failed Opus, I can tell you the performance was greatly improved on my 1980 SWII.
 

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Coil, rotor, and Opus if fitted can all cause those symptoms. Do the tests as I described in the previous post above rather than just replacing parts without knowing exactly what the fault is. It is easy to determine which part is defective when it stalls and won't restart until cool following those directions.
 

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Coil, rotor, and Opus if fitted can all cause those symptoms. Do the tests as I described in the previous post above rather than just replacing parts without knowing exactly what the fault is. It is easy to determine which part is defective when it stalls and won't restart until cool following those directions.
Thank you I will try...
 

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Just to be clear, for my 1974 Silver Shadow, do I need to replace the coil with The Pertronix model LU-281 (can I buy a more powerful one, and will it make any difference?), and what is the correct model Pertronix Electronic Ignition kit (Currently has Lucas Distributor cap)?
 

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You do not need the Pertronix coil. The only item that is changed with the upgrade is the pickup sensor, and the ring around the distributor shaft.
Again, the Pertronix # LU-281
 

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I would certainly replace the cap and rotor with genuine Lucas while you're at it.
 
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