qkingston Posted April 23, 2022 Report Share Posted April 23, 2022 So trying to get the 4a started after the complete rebuild. I have a newly rebuilt distributor from Martin Jay plus new Pertronix Flame Thrower coil supplied by him. New loom, new spark plugs (Champion L82C) and new leads. Engine turns over fine and all other electrical function are tested ok. I have 12V at the coil +ve but no spark from the King Lead (using a spark tester), other than a duff coil what else might be the fault? Many thanks David Quote Link to post Share on other sites
Lebro Posted April 23, 2022 Report Share Posted April 23, 2022 Check the points, & the thin earth wire inside the distributor, & the capacitor. Is the firing order correct, Is the ignition timing right - how did you set it ? Is the valve timing right ? Bob Quote Link to post Share on other sites
boxofbits Posted April 23, 2022 Report Share Posted April 23, 2022 You should at some point get a spark, even if the ign/valve timing is out. As Lebro comments the baseplate earth is important. Sometimes the points have an oil residue on them from storage, so will need cleaning. With the distributor cap off, do you get a spark when you carefully open and close the points with ign on with the tip of a screwdriver ( do not earth the screwdriver in any way. When I got my distributor back from DD I didn’t need to touch or adjust anything other than timing, so coil is a possible but not probable. Kevin Quote Link to post Share on other sites
qkingston Posted April 23, 2022 Author Report Share Posted April 23, 2022 Thanks Bob, I guess I was taking the distributor as a unit being correct as supplied and calibrated by Martin Jay. Firing order checked correct. I've rechecked TDC using a piston stop, checked the points, dwell angle and static timing using a Gunson Sparktune meter, followed RobH's fault finding guide, but still no sign of a spark...I'm scratching my head David Quote Link to post Share on other sites
qkingston Posted April 23, 2022 Author Report Share Posted April 23, 2022 3 hours ago, boxofbits said: You should at some point get a spark, even if the ign/valve timing is out. As Lebro comments the baseplate earth is important. Sometimes the points have an oil residue on them from storage, so will need cleaning. With the distributor cap off, do you get a spark when you carefully open and close the points with ign on with the tip of a screwdriver ( do not earth the screwdriver in any way. When I got my distributor back from DD I didn’t need to touch or adjust anything other than timing, so coil is a possible but not probable. Kevin Thanks Kevin, I've checked for spark at the points as suggested and that works...so distributor cap?? Quote Link to post Share on other sites
roy53 Posted April 23, 2022 Report Share Posted April 23, 2022 lead coil to distributor fault? cap? Rotor arm my bet Roy Quote Link to post Share on other sites
qkingston Posted April 23, 2022 Author Report Share Posted April 23, 2022 Yes I suspect leads or cap potentially. Rotor arm as supplied by Distributor Doctor so I hope not... Quote Link to post Share on other sites
boxofbits Posted April 23, 2022 Report Share Posted April 23, 2022 Could be any of the above. You could check the points open ( about 0.015”) on the heel ofthe distributor cam. DD might just have screwed them in without gapping. Make sure your rotor is turning. Sounds okay electrically otherwise. Kevin Quote Link to post Share on other sites
qkingston Posted April 23, 2022 Author Report Share Posted April 23, 2022 Thanks Kevin, is there a preference between the side entry and top entry caps? I have a Lucas side entry spare which looks well made, but went with the top entry to suit the push on silicon leads. What sort of resistance value would you expect from a lead? I measured between the coil +ve terminal and the HT connector : 10.24 KΩ, I then connected the king lead to the cap and measured 12.23KΩ from the terminal, sounds a bit high? David Quote Link to post Share on other sites
Dic Doretti Posted April 23, 2022 Report Share Posted April 23, 2022 If there is no spark at the king lead and the distributor has been rebuilt by the Distributor Doctor and there is a spark at the points then I would suspect the coil. Cheers Richard Quote Link to post Share on other sites
Lebro Posted April 24, 2022 Report Share Posted April 24, 2022 12 K for an HT lead sounds about right. Bob Quote Link to post Share on other sites
Waldi Posted April 24, 2022 Report Share Posted April 24, 2022 Agree with Richard, Can you try another coil? And is the distributor turning when you crank the engine (is it engaged with the cam shaft drive). Waldi Quote Link to post Share on other sites
ianc Posted April 24, 2022 Report Share Posted April 24, 2022 Coil is mounted on inner wing, but I cannot see evidence that its can is earthed - if no earth, no spark. If no earth to the coil's can, then run an earth lead to one of its clamping bolts. Ian Cornish Quote Link to post Share on other sites
RobH Posted April 24, 2022 Report Share Posted April 24, 2022 11 minutes ago, ianc said: Coil is mounted on inner wing, but I cannot see evidence that its can is earthed - if no earth, no spark. Sorry Ian but that is incorrect. There is no electrical connection to the can of a coil and it does not need to be earthed. The only low-tension connections are to the two tags. Quote Link to post Share on other sites
qkingston Posted April 24, 2022 Author Report Share Posted April 24, 2022 13 minutes ago, ianc said: Coil is mounted on inner wing, but I cannot see evidence that its can is earthed - if no earth, no spark. If no earth to the coil's can, then run an earth lead to one of its clamping bolts. Ian Cornish That's a good point Ian, I'll check that David Quote Link to post Share on other sites
qkingston Posted April 24, 2022 Author Report Share Posted April 24, 2022 1 minute ago, RobH said: Sorry Ian but that is incorrect. There is no electrical connection to the can of a coil and it does not need to be earthed. The only low-tension connections are to the two tags. Ah thanks Rob. Your fault finding guide is very helpful Quote Link to post Share on other sites
RobH Posted April 24, 2022 Report Share Posted April 24, 2022 (edited) post removed - this reply was not necessary as the previous one had been read. Edited April 24, 2022 by RobH Quote Link to post Share on other sites
stuart Posted April 24, 2022 Report Share Posted April 24, 2022 You have checked that the distributor is actually turning I take it? Stuart. Quote Link to post Share on other sites
boxofbits Posted April 24, 2022 Report Share Posted April 24, 2022 15 hours ago, qkingston said: Thanks Kevin, is there a preference between the side entry and top entry caps? I have a Lucas side entry spare which looks well made, but went with the top entry to suit the push on silicon leads. What sort of resistance value would you expect from a lead? I measured between the coil +ve terminal and the HT connector : 10.24 KΩ, I then connected the king lead to the cap and measured 12.23KΩ from the terminal, sounds a bit high? David Hi David You don’t really need to get into measuring resistance values of leads and all that. Put a plug lead into the coil (try 2 or 3) with a spark plug inserted, and flick the points open with the tip of a screwdriver as before with ign on. You should get a spark at the plug ( make sure the plug is earthed to the engine or the body). As advised above, make sure the rotor is turning when you turn the engine over on the starter. If it is, you should also try another cap and leads. Hope you trace it. Kevin Quote Link to post Share on other sites
Michael Mckiernan Posted April 24, 2022 Report Share Posted April 24, 2022 Hi David , have you checked that you still have 12v at the coil when the engine is turning over ? Possible that the feed drops out when you crank it over. Mick Quote Link to post Share on other sites
Charlie D Posted April 24, 2022 Report Share Posted April 24, 2022 1 hour ago, Michael Mckiernan said: have you checked that you still have 12v at the coil when the engine is turning over ? That reminds me. I’m not sure if the ignition switch is the same as it used to be when I had a Herald, but I had a similar problem after a rewire. I eventually discovered that I had wired the coil circuit to the “Radio” terminal on the ignition switch. This gave 12 volts to the coil when the ignition was turnrd “ON” but when I turned it to “Starter”, the feed was switched off. (The logic being that you don’t want the radio on when you spin the starter over in case the interference deafens you.) Maybe a total red herring, but worth checking you have volts to the coil when the starter is spinning, not just when the ignition is on. If not, and there is a connection for the radio on the ignition switch, maybe that is where the problem lies. Charlie. Quote Link to post Share on other sites
qkingston Posted April 24, 2022 Author Report Share Posted April 24, 2022 Ok got it sorted and started first time since the restoration started 3yrs ago! Checked the condenser securing, changed the cap and the leads and hey presto! Now the ignition warning light doesn't go out, the carbs need setting up properly (won't idle on no choke), but sounds pretty smooth so I think the timing end is pretty close. Thanks for all the really helpful advice, a major milestone! David Quote Link to post Share on other sites
ianc Posted April 25, 2022 Report Share Posted April 25, 2022 Well done, David. Onward and upward! RobH is correct and I was wrong - there is no earth required to the coil's can. Ian Cornish Quote Link to post Share on other sites
MilesA Posted April 25, 2022 Report Share Posted April 25, 2022 14 hours ago, qkingston said: Now the ignition warning light doesn't go out, Well done. Also had this issue after a partial loom rebuild by me. I had failed to connect / connect properly the lead from the alternator. Problem solved. Worth checking if you have one. Miles Quote Link to post Share on other sites
qkingston Posted April 25, 2022 Author Report Share Posted April 25, 2022 I'm on a roll, sorted the ignition warning light! I took the alternator plug off to do a continuity check on the Brown/Yellow wire to the warning light (OK) then when pushing the plug back on it went into the socket a little deeper and the warning light extinguished almost immediately on start up. On to the next one.... Quote Link to post Share on other sites
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