Darren Groves Posted June 13, 2018 Report Share Posted June 13, 2018 I have a confession, this question actually relates to a MG B not a Triumph...but a pretty universal issue I'm sure. I haven't owned a car with points for over 25 years, so I'm asking this in the hope I have overlooked something to check, so here goes: The car ran OK, was parked up for a few weeks then wouldn't start. Managed to get it to start by just cleaning the old points, but it wouldn't rev or idle, so the owner sourced plugs, points, Condenser & a Rotor Arm....fitted all these and then had no spark at all. Dizzy cap off, ignition on and manually open the points and there was hardly a spark and that was inconsistent. So we got another set of points and condenser and that fixed the this problem, great I thought. Dizzy cap back on, crank it over and still no spark at the plugs.....off with the cap, manually check the spark, still good so crank it over with the cap off, points opening and closing OK but again barely a spark and it's inconsistent. So seems that the spark at the points is fine if the car is not being cranked over but poor when it is. I have found several spade connectors that were barely making contact and the battery connections were very crusty, so will clean and recheck those today, but any other suggestions? Thanks. Link to comment Share on other sites More sharing options...
Guest Posted June 13, 2018 Report Share Posted June 13, 2018 Hello Darren, The wiring points you mentioned may prove to be the answer - obviously something has deteriorated during the lay-up and perhaps that could be earth wire(s) related. Might be worth checking the coil and rotor arm with known good units to eliminate those suspects. Dealing with the above will at least give you a better picture as to how it stands. Good luck. Richard. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 13, 2018 Report Share Posted June 13, 2018 Disconnect the dizzy neg lead and add a short wire , flash it to earth and the coil should discharge aspark, this just eliminates the dizzy internals, if no crack then suspect a coil problem There are some awful condensers on sale, Is the dizzy got a post and nut for the points or the clip type connectionsn? Is the base plate earth wire intact under its cotton sleeve ?? Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 13, 2018 Report Share Posted June 13, 2018 If there's a good spark without cranking it's unlikely to be the condenser? I would check the earth strap to the engine, it carries a lot of juice when cranking. They can look OK but appearances can be deceptive. Put a jump lead in parallel with the strap and try again this will tell you if it's OK or not. Doug Link to comment Share on other sites More sharing options...
JohnD Posted June 13, 2018 Report Share Posted June 13, 2018 A working condenser is there to suppress the spark at the gap else the arcing will wear out the points much more quickly. Good test from Peter (IIMSS). Add, put a plug on the dizzy end of the coil to dizzie HT lead earth the plug and crank. That will show if the points/coil/lead part of the system is working. John Link to comment Share on other sites More sharing options...
Darren Groves Posted June 13, 2018 Author Report Share Posted June 13, 2018 In answer to some of the replies above. We had another car in the Workshop with a 25D Distributor which we new worked fine, so ended up robbing points, condenser, earth lead and coil from that so I know the parts on there should be good. The battery has had a charge overnight so I will get cleaning up and securing the loose spade conenctors and main battery cables and earths.... Many thanks Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 13, 2018 Report Share Posted June 13, 2018 its worth a check that the ign switch is actually passing the voltage down the white coil feed nothing in = nothing out just a thought Pete Link to comment Share on other sites More sharing options...
Darren Groves Posted June 13, 2018 Author Report Share Posted June 13, 2018 2 minutes ago, Pete Lewis said: its worth a check that the ign switch is actually passing the voltage down the white coil feed nothing in = nothing out just a thought Pete Will do.... Link to comment Share on other sites More sharing options...
Paul H Posted June 13, 2018 Report Share Posted June 13, 2018 This is the cheat sheet I take with me ( based on problems I had with initial set up Im sure its not perfect and totally comprehensive - Ill know when I have to use it !!! Paul Link to comment Share on other sites More sharing options...
Darren Groves Posted June 13, 2018 Author Report Share Posted June 13, 2018 Car now running fine. Cleaned both battery connections, battery to body connections, removed and cleaned the engine earth strap, replaced spade connectors on both coil connections and dizzy, turned her over and she spluttered into life and ran.....on 2 cylinders. But once I'd cleaned out the solidified fuel from the float bowls, she ran very sweet. Thanks for all the suggestions. 2 Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 13, 2018 Report Share Posted June 13, 2018 Well done Darren! Always the simples stuff! Doug Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 14, 2018 Report Share Posted June 14, 2018 Good when its also .....cheap Pete Link to comment Share on other sites More sharing options...
JohnD Posted June 14, 2018 Report Share Posted June 14, 2018 That proves that an engine will run if given air, fuel and a spark even in very roughly the right quantities/time. Doug did a lot of things to the low volts side which makes the actual fault difficult to know, but that's academic - and he fixed it! That's the electric side. A useful diagnostic test if you think fuelling is wrong is a spray of "KwikStart", StartYerBastard, or similar into the air intake. If it does start, even just to turn over and then fail, that confirms your suspicion and you can concentrate on fuel supply as the fault. John Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 14, 2018 Report Share Posted June 14, 2018 5 minutes ago, JohnD said: Doug did a lot of things to the low volts side Did I? Doug Link to comment Share on other sites More sharing options...
JohnD Posted June 14, 2018 Report Share Posted June 14, 2018 Sorry - Darren! Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 14, 2018 Report Share Posted June 14, 2018 The problems of senior forums thank Bill Who's Bill Tom, I dont know Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 14, 2018 Report Share Posted June 14, 2018 Thursday? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 14, 2018 Report Share Posted June 14, 2018 chief inspector ......... Fred Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 14, 2018 Report Share Posted June 14, 2018 Pete, Your diligent repost shows endeavour. Doug Link to comment Share on other sites More sharing options...
Gully Posted June 14, 2018 Report Share Posted June 14, 2018 You two should show some remorse... Gully 1 Link to comment Share on other sites More sharing options...
SpitFire6 Posted June 14, 2018 Report Share Posted June 14, 2018 On 13/06/2018 at 10:28 AM, JohnD said: A working condenser is there to suppress the spark at the gap else the arcing will wear out the points much more quickly. Good test from Peter (IIMSS). Add, put a plug on the dizzy end of the coil to dizzie HT lead earth the plug and crank. That will show if the points/coil/lead part of the system is working. John Hi, I will add that a condenser/capacitor needs to be of the correct value to minimise wear at the points. Having the correct value of capacitance will also increase the power of the spark. Incorrect value will leave a tit and crater on the points contact; The tit & crater shows that the capacitor/condenser does not match the coil, leads and plugs. Increase or decrease the value to decrease the erosion; can't remember which way to go. Fit a Sparkrite ignition system and don't worry. Cheers, Iain. 1 Link to comment Share on other sites More sharing options...
JohnD Posted June 15, 2018 Report Share Posted June 15, 2018 Iain, Thank you! I should know that but I don't. What parameters govern the value of the capacitor? Coil and HT voltage is fairly standard, so number of cylinders and hence dwell time, what else? You mention plugs, which may be 'resistance' type or not, HT leads also various types, mainly to increase resistnce and suppress radio interference? John Link to comment Share on other sites More sharing options...
Ben Caswell Posted June 15, 2018 Report Share Posted June 15, 2018 How do you measure the value of capacitance ?? Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 15, 2018 Report Share Posted June 15, 2018 Ben, It's sometimes written on the side. But normally you take it on trust as the one for your model. This thread was sorted out at the beginning when Darren said. On 13/06/2018 at 8:25 AM, Darren Groves said: the spark at the points is fine if the car is not being cranked over but poor when it is Therefore the capacitor is fine and the fault is something else, possibly and earthing fault. And so it turned out to be. The final exchange is academic. db Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 15, 2018 Report Share Posted June 15, 2018 There were reports of cutting condensers open and only having 1ft of waxed foil, not the 9ft required There some ideas about this on distributor doctors site Pete Link to comment Share on other sites More sharing options...
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