Capacitor Discharge Ignition CDI Module Tecumseh 3.5 two cycle

[stilllearning6]

No decal label on the Vacuum / Shredder 3.5 HP Tecumseh LAV two cycle engine.
Circa approx 1975- 1985 ???
Trying to replace the ignition trigger ( CDI) .
Only markings are : "Tecumseh 4 340 ".
Can anyone help me ID the replacement part number / vendor ?
Are there updated replacement units available?

 

[Fish]

The Tecumseh numbers should be stamped into the starter cover somewhere, you need to find those.

 

[stilllearning6]

I examined the cover of the rope pull starter prior to my post and saw no markings.
I thought that perhaps the engine block would have something embossed into the block but I did not see anything.

The Vacuum/ Shredder closely resembled a previous machine that I owned which was a :
SEARS Model # 143 . 234 262
Serial # 3 186 C per riveted engine decal label

----------------------------------------
The equivalent of that model was a Tecumseh
CRAFTSMAN 143.234262 => TECUMSEH LAV35-40772K.

The previous similar Sears Craftsman Vacuum Shredder had a set of contact breaker points located under the flywheel.
The model that I am trying to fix does not have contact breaker points.
The rest of the engine / chassis / frame looks to be the same, except that the model that I am trying to fix has a carb which appears
slightly different because it has a fuel bowl underneath the carburetor.

I realize that you are trying to help me. Wish I could read something on the engine / cover/ frame.
This may/ may not have been a Sears Craftsman machine. I do not know, found in salvage.

 

[motoman]

learning, Due respect try cleaning up the spade contact covered with rust and the female mating one? CDI ignitions were the rage add on for cars too in the 70's. They were replaced by transistorized units. The guys on the forum are knowledgable about replacement coils similar to Magnetron (Briggs). Would seem the main consideration is mechanical attachment and timing point. Maybe you can find a drop in?

 

[stilllearning6]

Motoman-
yes, I did polish the coil rust to be shiny and also polished the flywheel magnet with 120 grit this morning.
Used a business card to set the air gap.
Also, I disconnected the cut-out wire , so as to bypass any possible short circuit to ground.
Result when spin flywheel after the polish / disconnect the cutout wire : no spark on brand new Champion plug which was held next to polished engine block. Bad news.

Googled whether I could ohm-out the solid state ignition coil to see if continuity in primary circuit could be proven.
My understanding is that continuity test with ohmmeter does not apply to a solid state ignition coil as it would
apply to an automobile ignition coil .
Is that true?

I tried to ohm out the high tension lead to the ground terminal to which the shut-off wire would attach.
Result: open circuit, infinite resistance. That would make sense to me. No info revealed .


I also ohmed-out the solid state high tension lead to the solid state ignition metal body .
Result: open circuit, infinite resistance.
I interpreted that as good news, no internal short to ground.

Please keep the input coming .

Can someone advise me what replacement ignition coils will work in the 3.5 HP , 2 cycle LAV Tecumseh?

I do not understand how to differentiate one solid state coil vs. another.
They all look the same , yet different engines specify different coils. Why?
What is the danger of installing a more powerful solid state ignition? The hotter the better ??
The original solid state ignition had a low profile flat rectangular shape, no cylindrical hump in the middle.

 

[Rivets]

You need to start over with your thoughts. 1. Tecumseh LAV engines are 4-cycle engines, not 2-cycle. 2. More likely if you mix the oil with the gas you have either a TVS or HSK engine. 3. All solid start coils cannot be tested the conventional way, you need a special piece of equipment to properly test them. Any readings you get don't mean to much. The coil I think you will need is Tecumseh part number 34443D. This is a common coil and most good repair shops should have them on hand. Take your old coil in and have them match it to this coil. Two things have to match up. The curve of the lamination legs and the position of the oblong mounting holes. If they both are a match, this coil should work for you. Read my signature before you take my advice, as other posters feel I don't know what I am taking about without model numbers.

 

[stilllearning6]

Rivets , thank you so much for your input. You are absolutely correct : 4 cycle , not 2 cycle as it does have separate oil and gas. I took the original part to 2 mower repair shops and neither guy could recognize the PN ; they both asked me for the missing model number.
I will chase after the PN 34443D as you suggested and try to match the dimensions .
Your input has been most helpful.

 

[motoman]

Still, Since you are interested...Your CD coil has germanium transistors which are even less able to stand heat than the silicone ones. As Rivets says, you cannot test solid state stuff with an ohm meter or DVM. That coil probably died in the 70's. The form and fit is probably all that would stop you using an after market coil. Try ebay and or small motor repair,go-cart and motorcycle shops . Looks like a great "antique" you are working on. If I see anything I will advise. :thumbsup:

 

[stilllearning6]

Motoman- thank you for your guidance.
I know little about solid state ignition and suspected that a multimeter would not help or else the internet would be full of threads /postings.

I am considering $20 new CDI PN # 34443D made in Argentina .
Don't know reliability.
Most of the 34443D on eBay are used. Cost vs. reliability.
I see that some photos of 34443D reflect a different shape / profile. I am skipping those as I do not know if they will fit.

You folks have been terrific. Much appreciation as I am still learning.

 

[motoman]

Still, Your best bet is of course a bolt on, but depending upon how adventuresome you are try "gardentractorpulling.com" which has a good overview of electronic ignitions. A universal set up for you looks like a little transisitorized "trigger" module to pick up crank position and conversion to a remote coil (delete your present coil and mount a different auto style coil). Probably not too expensive, (trigger $20), but lots of patience and experimentation.