Distributor not sparking in 1969 510

Discussion forum for the venerable 510, and its non-US counterparts, the Datsun 1600 and Bluebird.
chadidas
Posts: 3
Joined: Fri Feb 18, 2022 8:05 pm
Car: 1969 Datsun 510 L20B

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I have a Bosch distributor with a GM HEI that was working just fine, stopped working out of now. Have replaced the distributor, HEI, coil, and ignition and it still does not spark. Has anyone had this problem before? I'm starting to think it is a wiring problem (wires breaking and failing). At first the car would spark for a few seconds and then stop, then for a bout a second, then spark once or twice, but now it is not sparking at all. Thx for any help


macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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Does the HEI smell funny , burnt-out ?? Swollen or discolored ? Loose Coil by itself can be "sparked" via a cap wired in series (or parallel ?)...I believe with primary , and then simply completing the circuit with battery voltage and series 2 ohm resistor I belive , then quickly disconnect and capacitor fires primary . Is how you see the coil secondary's healthy sparks.
Last edited by macgiver on Fri Feb 18, 2022 9:22 pm, edited 6 times in total.

chadidas
Posts: 3
Joined: Fri Feb 18, 2022 8:05 pm
Car: 1969 Datsun 510 L20B

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No, it looks fine. no damage and resistance measurements match with a brand new one

macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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Wow - your ON IT ......OK.............. Hot-wire to eliminate ALL car wiring ? ya ?

chadidas
Posts: 3
Joined: Fri Feb 18, 2022 8:05 pm
Car: 1969 Datsun 510 L20B

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Hmm, I haven't thought of hot wiring it, but that sounds like the next best step. Have you hot wired a distributor before? I will search into it in the meantime

macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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It's been 25-30 years since I worked GM HEI's , my 75 Monte Carlo and 77 Nova Concours . But I mean you would run , from Pos. battery post , a FUSED (15-20A) jumper also with a 1-2 ohm (like 5+ watt rated) resistor in series directly to the PROPER connection on the HEI , the B+ battery input ,ya know - NOW crank engine ! Should start ? No ?........Aligator clips work great here.
Oh and you would have removed what wiring from car circuit was on that HEI terminal I'm telling you to jump hot-wired , to eliminate car circuit AND for safety sake :yesnod

p.s. You may have to run new jumpers from coil to HEI , but ohming them disconnected will tell if this is needed too. Inductive pickup inside distributor is more challenging to diagnose , never needed to go there.

macgiver
Posts: 1612
Joined: Wed Jul 04, 2007 10:21 am

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Me rethinks this while enjoying a cup of coffee today , and I'm going to tell you to put a "spotlight" on the capacitor or aka condenser , maybe resides inside distributor . A marginally failing "cap" WILL do exactly what your seeing - car runs initially , then peter out quickly .......next day (after time) SAME THING . I"M 90% sure , capacitors are the weakest link here , they do ultimately fail over time - simply a matter of time.
So if you can substitute another to test this , or rightaway and buy NEW one. Capacitors of this type have an electrical value , microfarads ( seen written mf ) and coil's condensers / capacitor usually the in range of .25mf down to .02mf , and It coincides with matching the COIL's "demand" , the proper value is determined to give the maximum energy "store" & "transfer" over to the coil at the precise moment the HEI ( or 'points' in '60's cars ) does the "firing" in your ignition circuit !
Good luck :gapteeth:


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