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?
Attachments
#2
Fish
The Tecumseh numbers should be stamped into the starter cover somewhere, you need to find those.
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
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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.
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?
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.
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.
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.
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:
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.
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.
The ignition coil module that you suggested 34443D arrived today, installed it, got spark.
Fired up with starter fluid through air filter.
The module I ordered was stamped " Argentina". Cost $18.00.
It was missing a rivet to hold the plates together . I added a machine screw, locknut.
It was missing the spark plug boot. Salvaged the original spark plug boot.
Thank you.
Now to figure out the carburetor model in another post.
Here's what to do with the carb. Tecumseh needle/seat part number, 631021B.
Needle and seat replacement
Remove the carb, and then remove the float bowl. Check the float bowl jet (which is the bowl screw) and make sure the jets both horizontal and vertical are clean and open. Tip the carb upside down and remove the float pin and float with needle attached. Look in the float needle passage and you should see the red float seat at the bottom of the passage. This is where a #5 crotchet hook would come in handy as you need to remove this seat. If you have no hook, but compressed air, you can blow through the fuel inlet and try to pop the seat out. Put your thumb over the passage to prevent the seat from flying who knows where. No air or hook try bending a stiff paper clip to dig the seat out.
I would either give the carb a good 24 hour soaking or have it ultrasonically cleaned at this time.
With the seat out clean the passage way with carb cleaner. Now you must find a drill bit slightly smaller than the passage way, to be used to press in the new seat. Apply a very, very small amount of a very light lube to the new seat. 3-1 oil or lighter, to help seat it better. Carefully insert the new seat in the passage way with the rings on the seat down toward the carb body. Slowly and carefully force the seat down with the back end of the drill bit. Once it is seated, check to see that it did not flip and the rings are up. *Next check to make sure that the float does not have any liquid in it. *If it does, replace. *If everything looks correct, attach the new needle to the float and install with the float pin centered. It everything is correct, the float should seat level to the carb body, when looking at it upside down. If everything looks good reattach the float bowl, making sure that both the bowl gasket and the nut gasket seal properly. Reinstall on the engine and test unit. Remember to have patience and take your time. Good luck, but I don't think you'll need it.
PS: *On the side of some Tecumseh carbs you will find a plastic cover. *Under this cover will be an idle jet. *Remove it and check to see that the jet is open both horizontally and vertically. *You should be able to push the old float needle wire through the vertical opening.
Tecumseh carbs have a number stamped into the housing. that number can be used to match up to a carb kit, and sometimes a series of engines it was used on. older Tecumseh engines had the numbers stamped into the blower housing, but the newer engines has a sticker on the blower housing.
