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I have an 80's AV520 670-05F 3hp 2cycle vertical shaft engine that does not have spark.
I have replaced the coil, condenser, and points. The kill switch is good and actually not connected at the moment. The points and plug are gapped correctly, the flywheel magnets are good, the air gap is fixed on this model, I can feel the spark when holding the plug wire and spinning the flywheel by hand but when i insert the plug in the wire and ground to the engine there is nothing. I am completely stumped why I'm not getting spark. I have another same motor that gets the exact same meter readings at every point I check and gets great spark when tested by hand.
It is acting like the kills switch is connected and off even though it is not. Is there anything that could be grounding causing this no spark issue?

"I can feel the spark when holding the plug wire and spinning the flywheel by hand"

Sounds like the points are slightly out of time with the magnets. Try opening the points gsp a couple thou. If that doesn't help then close a couple thou.

Sounds to me like your timing is not correct. This will happen if you removed the magneto assembly. Timing these ignition systems is not easy unless you have the proper dial indicator. It can be done without the indicator if you have experience in how the indicator is doing its job, but does take time and a good vernier caliper. Here is a manual which tells you how to set timing. https://www.mymowerparts.com/pdf/Te...HSK600-TVS600-Craftsman-200-Series-692508.pdf

Rivets said:

Sounds to me like your timing is not correct. This will happen if you removed the magneto assembly. Timing these ignition systems is not easy unless you have the proper dial indicator. It can be done without the indicator if you have experience in how the indicator is doing its job, but does take time and a good vernier caliper. Here is a manual which tells you how to set timing. https://www.mymowerparts.com/pdf/Te...HSK600-TVS600-Craftsman-200-Series-692508.pdf

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This model has a keyed cam for the timing. The key has not sheared so the timing should still be good. I have read through this manual and checked every position and gap for this motor and everything is correct. When I hold the plug wire and spin the flywheel, I can feel the spark at both points (wire and flywheel) but I get nothing from plug to motor which makes me think something became grounded, I just cant find where.

Sorry, but you are wrong. The cam may be keyed, but the timing is adjusted by moving the magneto assembly. Trust me, I grew up with these engines.

Rivets said:

Sorry, but you are wrong. The cam may be keyed, but the timing is adjusted by moving the magneto assembly. Trust me, I grew up with these engines.

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Fair enough. I will go back and re read and double check everything. But if the timing is off, wouldn't I still get spark, just at the wrong time?

Not going to get into an argument how the old Tecumseh ignition systems work. Bye.

If the magneto assy wasn't moved that's good. Moving the mag/coil assy adjusts the engine timing but the points gap is critical to timing the magnets to the coil.

You are assuming that the old points gap was the same as what the new points gap is set at. We’re talking thousands of an inch which is very critical. I’ve seen Tecumseh engines run at point gaps ranging from .016“-.022”, depending on how the timing was set. Also, your condenser may be bad, which will also affect spark strength. I still test condensers today when ever working on these systems. Don’t need special equipment if you’re not afraid of getting shocked once in awhile. Here in Wisconsin we still have a lot of the old mule SnowKing engines being used.

Rivets said:

Not going to get into an argument how the old Tecumseh ignition systems work. Bye.

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wasn't trying to argue. you are correct about timing being off. I'm not a motor guy. was just asking a question

Hammermechanicman said:

If the magneto assy wasn't moved that's good. Moving the mag/coil assy adjusts the engine timing but the points gap is critical to timing the magnets to the coil.

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I replaced the magneto, condenser and points so I did move everything. I reset the point gap to .020. The timing is probably off and I will have to adjust that, But would I still get spark (at the wrong time) if the point gap is set correctly? I am not and that is what I'm trying to figure out.

You must understand the relationship between the points, condenser, and coil which most work together to produce voltage to cause a spark plug to fir. Timing on the Tecumseh engines with the magneto and points mounted under the flywheel will affect spark. Incorrect timing on a small engine with points can definitely cause a weak spark, as the timing determines when the spark occurs in relation to the piston position, and if it's off, the ignition coil may not have enough time to fully charge, resulting in a weaker spark.

Rivets said:

You must understand the relationship between the points, condenser, and coil which most work together to produce voltage to cause a spark plug to fir. Timing on the Tecumseh engines with the magneto and points mounted under the flywheel will affect spark. Incorrect timing on a small engine with points can definitely cause a weak spark, as the timing determines when the spark occurs in relation to the piston position, and if it's off, the ignition coil may not have enough time to fully charge, resulting in a weaker spark.

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Thank you. I appreciate your help.

So I broke it all the way back down. Found the timing cam has a crack in it and was installed upside down (I imagine from the person i bought it from trying to get it to run). Cleaned all the rust off the armature the coil goes on. Reinstalled the new coil, condenser and points. Set the point gap to 0.20 per tecumseh manual, set the timing to .070 btdc per manual.
And I'm still getting a weak spark. All wires are good and have good connections. Magnets in flywheel are strong.
I'm at a loss. I even checked and compared all readings and set points to my running av520 and everything looks good.
Can the laminate armature go bad on these ignitions?

Reply

I’ve gone to my archives and there are a couple of things you should know about the AV520 engines. First, the AV520 engine was only built as a 3hp engine in 1975&1976, before and after that they were 3.5hp. Second, they were made as an outboard engine, Eske manufacturing was the primary user, with a small number also used on other pieces of ground equipment. Adjusting and setting the ignition systems on these engines was different depending on where they were used. Third, spark plug needed for these engines was either a Champion J13Y or RJ13Y or AC 45S. Using a hotter plug will produce a weaker spark. Can laminations cause a problem, yes if they become separated.

Rivets said:

I’ve gone to my archives and there are a couple of things you should know about the AV520 engines. First, the AV520 engine was only built as a 3hp engine in 1975&1976, before and after that they were 3.5hp. Second, they were made as an outboard engine, Eske manufacturing was the primary user, with a small number also used on other pieces of ground equipment. Adjusting and setting the ignition systems on these engines was different depending on where they were used. Third, spark plug needed for these engines was either a Champion J13Y or RJ13Y or AC 45S. Using a hotter plug will produce a weaker spark. Can laminations cause a problem, yes if they become separated.

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Thank you for the info. My engine is from a 1980s model 30 jiffy ice auger. It is running a rj13y plug. I could not find an engine model number and assumed it was the same as my older 76 auger which has a metal engine tag as the look identical. I will have to track down where to find the engine model number and start over.
I really appreciate your time and knowledge.

jleb said:

Thank you for the info. My engine is from a 1980s model 30 jiffy ice auger. It is running a rj13y plug. I could not find an engine model number and assumed it was the same as my older 76 auger which has a metal engine tag as the look identical. I will have to track down where to find the engine model number and start over.
I really appreciate your time and knowledge.

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Sorry my plug is a RJ17LM

Rivets said:

I’ve gone to my archives and there are a couple of things you should know about the AV520 engines. First, the AV520 engine was only built as a 3hp engine in 1975&1976, before and after that they were 3.5hp. Second, they were made as an outboard engine, Eske manufacturing was the primary user, with a small number also used on other pieces of ground equipment. Adjusting and setting the ignition systems on these engines was different depending on where they were used. Third, spark plug needed for these engines was either a Champion J13Y or RJ13Y or AC 45S. Using a hotter plug will produce a weaker spark. Can laminations cause a problem, yes if they become separated.

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Sorry, correction
My plug is a RJ17LM

Ok, now I feel like a fool, because I ASSUMED what was posted was the truth. Another DIY got me to fall for the switch and bait trick. Looking back I should have realized that things weren’t really as posted. Clue was when he stated timing doesn’t affect spark, good mechanic would know better. Guess my age is affecting my judgment, congratulations you got me.

Contacted jiffy (Feldman co.) And they confirmed my engine is an av520 670, 3hp. Set timing and point gap to correct values. Swapped each component out one at a time (checking all gaps each time) and still the same outcome every time. Getting only weak spark. Enough to feel but not enough to produce spark at plug. So unless anyone else has an idea I think I'm giving up on this one.

Last grasp at the straws.
I believe the engine has an external coil. If so try this. Disconnect the points wire from the coil. Connect an ohm meter to the wire from the points and to ground. Slowly turm the engine and see where the points open and where the flywheel magnets are in relation to the coil legs. Do they line up?