Magneto on 1960's Tecumseh 3hp

[creeksidesalvage1902]

Hey all, I've been working on this old snowblower and discovered it has no spark. It has an old 3hp Tecumseh motor. I took the flywheel and magneto off, replaced the coil,condenser,and points double checked eveything is hooked up right and points are gapped to the specs. (.020") After that I put everything back together and ...nothing. The Parts I got are correct,fit and look like the old coil,etc.... I don't get it Help!


Thanks all! -Danny ((Grand Forks ND))

[K D Redd]

You should have ask your question before you threw all of those parts at it. Most likely you had a simple problem. Now there is no telling what problems you have introduced. Be sure you do not have the insulated side of the points grounded somewhere.

Kent

[creeksidesalvage1902]

Yikes? Really? More problems? I thought it'd make things better with new parts?. Besides the points are there other adjustments to be made? Also I will double check the points as well to check the grounding issue.

[Sky]

Is this magneto UNDER the flywheel? If so, have you had it off? If you have, did you mark the position you took it off?

[creeksidesalvage1902]

Yeah I took the magneto off, but marked where it was positioned, put it back exactly, and nothing.....

[Sky]

Ok. Best i could tell you is a potential ground out somewere.

[makoman1860]

Just because you put it back where it was, doesnt mean its right. 90% of the time I have found peoples troubles with that system to be timing. Use the indicator method and actually set the point opening time, then check to make sure the magnets are actually slightly past magnetic neutral when the points open. Oh and you did check to make sure the kill switch is working correctly right??

[creeksidesalvage1902]

wow, What is the procedure to use the "indicator method", and where is magnetic neutral and how would I check the kill switch? I know the kill switch is connected to the throttle control on the carb, when you shift the throttle all the way slow the linkage catches on a "clip" which has a wire on it that leads to where the coil and condenser hooks up to the points.

[makoman1860]

If you dont have it, find and download the tecumseh service manual for your engine. You basicly need to set the points to open with the piston a certain distance BTDC. Guessing and Wishing doesnt work well with this mag. As for the kill switch, disconnect the kill wire from the primary terminal and test for continuity between that and ground, it shoud be open when running, and grounded to kill.

[Sky]

Honestly, you should be all right by any means if you marked the position from which it last came but it is true that this doesnt work ALL of the time.

The procedure is to obtain a continuity light and a new Nickle which is aprox. .080 BTDC which is what tecumsehs set at. Fallow me close.

What you do is disconnect the coil and condencer leading to the points so that the points are isolated. (by their selves)

Your also going to need to remove the head of the engine.

With the points set at .020, turn the engine as it comes to the top of the compression stroke. Before the compression stroke, set the nickle atop the piston nearest the valves and make this level to the deck AKA TOP, of the block. You will then see that you have aprox. .080 thousands of space BEFORE TDC on the compression stroke.

Here is were the continuity light comes in.

With this above set, hook the light to the points with the revolving plate or "stator" slightly loose. You set the position of the points JUST as the continuity light comes on. NO MORE.

Tighten the assyembly down. Re-check. If succesful, you will be in correct time.

Then re-assyemble.

If you have a persistant no spark situation then you have a dead ground somewere. I really beleive you have that in the first place.

[creeksidesalvage1902]

Well I tinkered with it some this afternoon, I did find that one of the wires from the coil that connects to the condesor mounting screw was touching the the bracket the coil plugs into on the magneto, I moved it over away from that. I also noticed that the spring part of the insulated side of the points was touching the base part that holds the other side of the points,.......this was a red flag to me. So I adjusted the points so the two sides were clear of touching (except at the point where they are susposed to come into contact of course) reset the gap to.020" and put the thing back together and now I know there's a bit of spark cuz when I spin the flywheel and touch the plugwire I get a good jolt, but I still don't actually see a "spark" from the plug but man it stings when you touch it the wire! So I don't know...Do I need to still adjust the timing? or adjust the magneto/flywheel distance it's self. The sparkplug is brand new. It's CJ8, I don't know if that's the right plug size since when I got it it had no plug. (there was just the bottom half of a old plug the porcelain plug had broke off. Since I don't know the exact model # this engine is. (The identifcation plate on the flywheel cover is gone and I couldn't see any numbers on the block at first glance.) The guy at the lawn mower shop told me a CJ8 would work, but he didn't seem like he really put alot of effort into making sure this is correct. So If anyone knows the right plug that goes to thins engine or could tell me what model or where to look for numbers on the block that'd be great!!!! THANKS for all the help so far! I really appreciate it!

-Danny

[K D Redd]

There are several spark plugs that will work in that engine with the CJ-8 being one. IN the CHAMPION plug line, yes many people do not like Champion but I have no problem with them, you can use the following plug types: J-8, CJ-8, J-17LM, J-19LM, RJ-17LM, and RJ-19LM. The reason it may have seamed to you that he did not put a lot of effort in finding the plug type is he like me know these numbers are used in MANY small engines.

Kent

[makoman1860]

Danny,
If the system is somewhat functioning as indicated by SOME secondary output ( the jolt you feel ), this is a good indication that you NEED to set the timing, and NEED to make sure there is a good ground between the coil ground and block. The timing is not so much for spark timing as it is for whats called "internal timing" on a stand alone magneto. If the points do not open at the correct position of the magnets vs coil laminations, you will not get much secondary energy as the field either never grew, or started to shrink before the primary circuit opened. Make sure the laminations to mag assembly are clean and bright, and the mag assembly to block interface is as well, then time the system.

[creeksidesalvage1902]

Originally Posted by Sky

Honestly, you should be all right by any means if you marked the position (of the mag) from which it last came but it is true that this doesnt work ALL of the time.

The procedure is to obtain a continuity light and a new Nickle which is aprox. .080 BTDC which is what tecumsehs set at. Fallow me close.

What you do is disconnect the coil and condencer leading to the points so that the points are isolated. (by their selves)

Your also going to need to remove the head of the engine.

With the points set at .020, turn the engine as it comes to the top of the compression stroke. Before the compression stroke, set the nickle atop the piston nearest the valves and make this level to the deck AKA TOP, of the block. You will then see that you have aprox. .080 thousands of space BEFORE TDC on the compression stroke.

Here is were the continuity light comes in.

With this above set, hook the light to the points with the revolving plate or "stator" slightly loose. You set the position of the points JUST as the continuity light comes on. NO MORE.

Tighten the assyembly down. Re-check. If succesful, you will be in correct time.

Then re-assyemble.

If you have a persistant no spark situation then you have a dead ground somewere. I really beleive you have that in the first place.

So how would you check and adjust the coil/flywheel distance? Should this be done before you time the engine? Like I said before I did mark where the mag mounted on the block but can this be checked and adjusted?

[makoman1860]

Cant adjust the distance, the mag pivots around a machined snout on the case. Just make sure ther is no corrosion or paint between parts that need to make electrical contact, make sure the cam is on correct ( letters out ) , time the point opening per the book, and you should be fine.

[creeksidesalvage1902]

SUCCESS! after timing the engine, (per Sky's help) I got great spark and put it all back together and it started on the third pull. Probably the first time it's ran in almost 10-15 years! So to all thank you very much.


-Danny

[makoman1860]

Amazing isnt it? Those style ignitions arent robust enough to be set up by guessing. Glad to hear its working.
-Aaron