Tecumseh HS50 timing - Snowblower Forum : Snow Blower Forums
 
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post #1 of 7 Old 02-24-2015, 04:39 PM Thread Starter
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Tecumseh HS50 timing

I have a 1980s Craftsman 5/22 snowblower with a Tecumseh HS50-67238E engine. I used it last year, then replaced the carburetor after the gaskets failed, and it is now out of service once again after blowing out the crank oil seal and filling the points case with oil. I replaced the seal and put it back together, observing bright blue spark. I went to start it, got a quick thud out of it, and no more spark. Turns out I sheared the flywheel key from not using a torque wrench (my bad).

I ordered a set of keys, but I am also looking at replacing the points and condensor while in there, as preventative maintenance. I'm not sure of the points gap and exactly how the timing is set on this engine. I see that there is room to slide the points bracket around - is that to set timing? How do I measure timing to adjust it. I have a timing light but am not sure if there are scribe marks somewhere.

Much thanks.
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post #2 of 7 Old 02-24-2015, 05:22 PM
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I'm sure others will help.

Set the point gap to .020 (it's marked on the points cover) Be sure to clean any trace of oil off the contacts. Trust me on that! As for timing, the "book way" involves measuring the piston BTDC using a dial indicator. I have never done it that way, just look for the scribe mark or make sure the bolt marks that hold the mag to the case are in the same spot. My mini bike days 42 yrs ago I would twist the mag counter clock wise to advance the timing.

Yeah I'm a hack. A good hack....
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post #3 of 7 Old 02-24-2015, 05:33 PM
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Hi dh
Welcome to the Forum. I'm with Scrappy on the timing...I have the dial indicator setup, but it's really not necessary. Just make sure you are on the highest point of the cam before setting to .020 on your gap. That will give you the proper advance on your ignition. Don't move the mag bracket...also not necessary. The flywheel key will line you up just fine. Good luck. MH

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post #4 of 7 Old 02-24-2015, 06:24 PM
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what they said...just put the points cam lobe on high spot on points, max open, and adjust the points to the proper gap. timing on these little engines is stationary, i.e. it's set by the position of the coil magnets to the flywheel and crank/piston. there's no need to adjust it, if it was running before. the coils are made to bolt on one stationary spot and stay there, and timing stays there.

having said that, point gap does move the timing as it is opened and closed, to some degree. closing the points retards the timing, opening them advances it. closing the points saturates the coil for longer, and the points open later, meaning the spark is fired later. opening the points, saturates the coil a shorter time, and opens the points sooner, making the timing a little sooner. on an old car with points, you can turn the points adjuster IN making the point gap smaller, and actually watch the marks on balancer/timing indicator, and see the timing back off, and hear the engine rpm go down slower. but it's really NOT the way to adjust timing, advancing the timing with less coil saturation, means the spark is not as hot. nothing it gained, spark energy is lost. the real way to advance timing, is move the coil on the engine. but again, nothing is gained, because these engines are maxed out by the factory for the cams they use. the factory engineers have a lot more time, money, and equipment than us, and they figured out the optimum settings and tune a long time ago, and made timing static i.e. nonadjustable.

so for simplicity sake, just set it to the recommended gap. don't try moving the coil, although you may want to check and set the coil gap. too close it rubs on the flywheel, too far away and it loses spark energy.

ps- better yet, get a Nova II ignition on Ebay, and you never had to change or set points again. and the timing will be dead nuts on rock solid, and not move with point gap variance due to wear




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Last edited by greatwhitebuffalo; 02-27-2015 at 06:33 PM.
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post #5 of 7 Old 02-25-2015, 06:29 PM Thread Starter
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Awesome information, thanks! I haven't touched the coil, so I will leave the timing as is and gap my points. Good to know about the electronic ignition alternative - looks like that unit can be had for about the same price as a new set of points. I will keep it in mind for the future.

Waiting on my flywheel key to come in the mail and will hopefully be running for the next big storm
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post #6 of 7 Old 02-27-2015, 01:17 AM Thread Starter
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Got it back up and running. I put one of those inductive tachs on while I was at it. The throttle is varying up and down a few hundred RPM as the throttle plate seems to be vibrating as it runs. Also it is idling at 3900 RPM on full throttle and runs 3600 under load.

Whats the safe RPM range on these and how do I stop that throttle plate from moving around?
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post #7 of 7 Old 02-27-2015, 05:44 AM
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The proper wide open throttle without load is 3600 rpm. You might be a tad high, or your tach may be off a bit. Make sure your crankcase oil full on the stick and you should be fine. The movement in the throttle plate may be due to "hunting," and the governor correcting the hunt. MH

1960 Ariens 45-10M
1961 Ariens 10M55
1977 Ariens 22000
1972 Ariens 10000
1990 Ariens ST724
1987 Toro 724
Murray Ultra 522
MTD Single stage
8 hp MTD hybrid plow
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