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Tecumseh Ssi Conversion To Battery/coil Ignition

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Posted January 11, 2013 - 09:29 PM

For any of you that has dealt with the SSI ignition on a Tecumseh motor either knows about the failed SSI module bug or has got bitten by it, I got "lucky" and got bit twice in 1 month leaving me with two non working OH160 motors/tractors. No way was I gonna pay $150-250 for a used 35 yr old ignition module from Evilbay. Next step was hit the net and do some searching for a fix. I came across Ed Stoller's website http://www.enginesandmagnets.com and decided to do his upgrade. Ed provides some great info and is a really nice guy to talk to. There are also available upgrades from Dale at Overnight Solutions and Brian Miller has a set up on gardentractorpullingtips.com, this is a thread on a different type of setup.  

I was talking about it to a friend Jon (searstractorfan) who I met on MTF and he said if I could wait a month or two, he was working on a prototype ignition he was adapting to a Tecumseh 12hp. He had a prototype and needed a real world test mule, I had a broken "mule" that needed a new ignition and we only live 45 mins apart.  


Here is link to a thread Jon started on his setup if you would like to read how we got to this point.



Here is my thread on MTF of my install on the tractor, basically same thing I'm posting here, but does have some questions from other members.




So the basic solution is to remove the SSI module which is the signal pickup/coil unit and replace with a magnetic or proximity pickup on the flywheel then to Chrysler control module/HEI module, then to a battery fed coil using the factory flywheel signal pins to trigger pickup. The system that Jon has come up with uses a micro switch which is triggered by a small magnet glued to flywheel then straight to a Bosch Blue coil. Jon had came up with the idea from using this magnet/switch on his alcohol fed pulling tractor. Worked well on a single Kohler puilling motor...why not adapt to a Tec motor. Once Jon did some bench testing, we transferred his parts to my OH160 and off to work it.I cut a field for almost 2 hours, plowed a garden, and some general work. 

I will say, this motor has ran better than it ever has, seems to run a little cooler and actually quieted down some.

The only drawbacks I see with this system is

1. Since system is now battery fed coil, must have good battery and charging system, but you will have to do this with any of other systems


2. You must remove trigger pins and drill/glue in magnets into flywheel. This is permanent,, but so is new system, I really didn't care.

3. Since this system uses the advance pin position on the flywheel, you may get some kickback on startup since the long pin is used for

    low rpm spark then it jumps to advance. I used a toggle switch to power coil so I just spin motor some, then flip coil on, not had

    kickback yet.


So, here is the list of parts and prices to complete the system. Jon figured about $110 to do complete system, but since he sees the vendors at local pulls, he can get discounts with out shipping,. My costs ended up around $140-150 which is about same as Ed's, Dale's, or Brian's so I guess it's a wash.


1. Single cyl flywheel pickup trigger
This comes from Midwest Super Cub and primarily used on Kohlers. I emailed them, asked for trigger only with out magnetic ring or bracket. Total was
$69.xx, make sure you ask for USPS flat rate mine was $6.25, UPS is $15 for shipping.


2. Bosch Blue coil
Jon recommended going through Nichols performance. You have to make sure you get a 3ohm coil, they had best price even with shipping and Ohio tax.
I paid $47.xx to the door.


I did find a no name brand coil that is supposed to be same as the Bosch, I can't recommend, use at your own risk.



3. Spark plug wire
Jon was using performance MSD auto wire and adapter on his coil, I happen to have an old set from a points car so I used that so no $$$ in this one.
Nichols lists wires on above link. I think Super Cub and also Brian Miller sell them. Maybe able to get just coil wires at local auto parts store also.

4. Off/on toggle switch
Pretty self explanatory, used to feed coil. Could also feed coil off ignition hot lead. I got a 20 amp switch from Tractor supply for $3.99.


5. Trigger bracket
Jon spent some time making this little bracket to get timing set to about 25* while running. I made a copy and can provide one if needed. You can make your own, just a same strip of steel with couple holes to match mount on old SSI unit, then mark where the SSI pickup lies, then mount the new trigger on the strip  No $$$$

6. Various connectors, wire, nuts/bolts
Depends on what you have. We both had most of spade/butt connectors/wire.
I did have to buy 2, 4-40 machine bolts and lock nuts from Menards, These cost about $1.29 or so total. These are super small bolts needed to hold trigger on brackets. Anything much bigger and they won't fit, super small.
I also used heat shrink on connections and installed fuse in line before switch, both I already had.


7. Magnet for Flywheel
Jon said he used the magnet from on old magnet screwdriver tip? The original pin holes are about 3/16" so I ordered 2 sizes just in case. I ordered both 3/16 and 1/4 and drilled flywheel to 1/4 and used the 3/16 glued in with JB Weld.  It is important to make sure magnet is oriented properly to trigger switch. I hooked up entire system, turning coil on and grounding plug on motor so you can see spark.

I then had magnet on end of a nail then checked to see which side triggered coil. Mark that end and make sure it gets mounted up so it triggers switch. Make sure you are touching tractor or plug when triggering coil.....don't ask how I know, DOH!!!!

3/16 x1/8 magnet http://www.kjmagneti...il.asp?prod=D32

1/4 x 1/8 magnet http://www.kjmagneti...il.asp?prod=D42



Pics in next post,......

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Posted January 11, 2013 - 09:47 PM

One thing to note also, make sure charging system is working, I actually am using a regulator from a Kohler 22hp Command in place of Sears Regulator with no issues. I used this tractor for about 6 hours off/on in Dec pushing snow with an electric winch and she never missed a beat the whole day.


So here is the trigger mounted about flywheel on home made bracket. You can see the magnet mounted in flywheel. I noticed when I mounted my trigger, I had to shave the ends slightly so I could mount it low enough to trigger coil. Trigger is made so you can shave ends to fit different diameter flywheels or the magnetic rings triggers are sold with.





This is just the switch set up I used. I came from the battery to an line fuse then to switch and then to positive side of coil. I utilized the hole in my dash for the rear electric actuator switch since my tractor does not have one.




This was the testing setup with Jon's stuff. kind of sloppy and we just used wire nuts. Worked fine for testing.





Here is the coil mounted. The black goes to the negative side on the coil, the positive goes to positive on the coil along with the positive feed from the toggle switch or ignition if you preferred.





Here is the final setup. I mounted coil to firewall behind battery which worked great. I used spade connectors and heat shrink on connectors to make it more professional looking. Not as clean as I wanted, but whole wiring system completely needs to be redone. Had to coil up  plug wire as it was a little long, but works fine.





This is just a pic with the pile of all Jon's parts after I installed mine. Just example of parts used.





So shoot with any questions, I will try to answer or try to find the answer for ya



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#3 chris m OFFLINE  

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Posted January 11, 2013 - 10:04 PM

That's great! I am sure this will help a lot of people that have dead Tec SSI engines and haven't found or wanted to spend the $250.00 or so to buy a used one. :thumbs:

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#4 KennyP ONLINE  



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Posted January 12, 2013 - 06:24 AM

Thanks for sharing this fix. I don't have one of these engines as yet, but I'm sure folks will find this useful.

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#5 Markski OFFLINE  

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Posted September 29, 2014 - 10:35 PM

Wish  there had been a fix for this 15 years ago. I junked out at least two old Sears because they had this problem!

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#6 John Arsenault ONLINE  

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Posted October 16, 2015 - 09:05 AM

Im thinking that if the magnetic pick up is mounted on a slotted bracket mount it would then be adjustable. a little to the left or right there goes a long way.

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Posted October 16, 2015 - 11:28 AM

Im thinking that if the magnetic pick up is mounted on a slotted bracket mount it would then be adjustable. a little to the left or right there goes a long way.


Yes, you could adjust the timing with a slotted bracket. This one was made to keep it  about 25* advance which is close to where we determined the SSI ran at.

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