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Tecumseh HH70 No Spark - Points & Timing Issues

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NCMichael
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2025/05/30 22:01:46 (permalink)
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Tecumseh HH70 No Spark - Points & Timing Issues

No spark issue.  Ordered new points, condenser and coil from this site.  Still nothing.  Found that points open properly, but do not fully close.  It appears the spring is too weak.  I reshaped the spring but did not help.  I could get the spring tight, but it would not pull the points in the correct direction to make good contact.  Luckily, I bought two sets.  I left the second set of points' spring at it original shape and it BARELY makes the points close.  But I cannot verify if 100% consistently closing while setting the timing.  Also, I am out of play in rotating the stator to get the points to open at 0.080" BTDC.  I can only get to about 0.085".  Not sure if something else is wrong that is causing these two issues.  Did I just get some bad points and need to get some new ones?
 
Any suggestions greatly appreciated.  An no, my key is not sheared. (That seems to be everyone's answer to no spark problems everywhere on the internet.)
 

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    SRTsFZ6
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    Re: Tecumseh HH70 No Spark - Points & Timing Issues 2025/05/31 07:16:00 (permalink)
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    Un-less I'm misunderstanding, the air gap should be  .020".
     
    An air gap of .080" likely would not even allow the points to close, that's your issue.
     
    Tighten up the gap.
     
    .
     
    .
     
    post edited by SRTsFZ6 - 2025/05/31 07:18:33

    Scott
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    NCMichael
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    Re: Tecumseh HH70 No Spark - Points & Timing Issues 2025/05/31 09:39:21 (permalink)
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    Yes, the points gap is set to 0.020".  The 0.080" refers to the distance of travel of the piston where the points should open before the piston gets to TDC, as measured with a dial indicator with the head removed.  One more bit of information.  If the timing is off (> 0.120" BTDC) causing the points to open way before 0.080 BTDC, the points seem to make contact with more spring force as I would expect them to all the time.  Wondering if I have a points issue or bigger engine issue.  I do not know the history of the engine.
     
    Thanks.
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    SRTsFZ6
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    Re: Tecumseh HH70 No Spark - Points & Timing Issues 2025/05/31 11:14:13 (permalink)
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    As you know, these engines are pretty simple and reliable.  
    Their also not as critical to run with that small a difference in TDC.
     
    Setting the coil in the middle of the adjustable range should run fine.
    Having the points set at .020" the a good flywheel key should be fine.
     
    Pretty un-common is for the flywheel to not be good.  I gather there's plenty 
    of magnetism? 
     
    Also, make sure all your grounds for points/ condenser, etc are super clean.
     
    As your probably not seeing spark, try both spinning over the engine with either a
    spark tester, or with your hand (your the tester) and with any kill wire disconnected..
     
    Lastly, just because it's new, does not mean it's good....
     
    Plz post back what you find
     

    Scott
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    SRTsFZ6
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    Re: Tecumseh HH70 No Spark - Points & Timing Issues 2025/05/31 11:21:20 (permalink)
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    Also, part #270:
    https://www.jackssmallengines.com/jacks-parts-lookup/manufacturer/tecumseh/4-cycle-horizontal/hh-70/hh70-140000/engine-parts-list-1 
     
    I believe (it's been many decades), that's the lobe the points ride on, is that correct?
    If so, it should be slightly oblong (to open and close the points).
     
    .

    Scott
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    NCMichael
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    Re: Tecumseh HH70 No Spark - Points & Timing Issues 2025/06/01 18:10:36 (permalink)
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    Thanks for the feedback.
     
    Yes, I have the oblong lobe and it opens and closes the points as expected. My problem is the points do not pivot all the way closed when the timing is set correctly. As in the spring is not pushing them tightly closed all they way. The points pivot freely so there is not any binding causing my issue. I have also checked the magnetism of the flywheel magnets with the nearby screwdriver test and they both appear to be strong.
     
    I left the timing slightly off at about 0.090" BTDC where the points just barely seem to close most of the time .... and of course open to the correct 0.020" gap. The tiller ran for about 2 minutes. It did not run well, it ran like it had weak spark LOL. But it ran for the first time I have owned it! It then shut off and I could not get it to start again.
     
    Next, per SRTsFZ6's suggestion, I am going to adjust the timing off more to where the stator is centered in its adjustment, to where the points will consistently close all the way and see if it will run better. Unfortunately, other life events will prevent this from happening for a month or so. But, I will post back on what I find.
     
    Thanks for all the help. This is my first time working with a Tecumseh engine and would not get it running without everyone's expertise.
     
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    SRTsFZ6
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    Re: Tecumseh HH70 No Spark - Points & Timing Issues 2025/06/01 19:14:59 (permalink)
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    Tks for the update and looking forward to your next post..
     
    .

    Scott
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