Stihl trimmer coils

[38racing]

I've concluded the coil on my friends older fs36 curved trimmer is bad. If directly grounded an inline tester will show spark but not when connected to a grounded spark plug. It will also not jump the gap on what I think is commonly called a briggs spark tester.
https://shop.briggsandstratton.com/prod ... qz-gOpltEd
A parts manual indicates
4130 400 1300 as the part number
I mistakenly bought a 0000 400 1300 from my supplier. Similar to the old one but one mounting hole doesn't match. A seller on amazon shows my part number and picture looks correct and it includes warning that it only fits old style. I can order it but I have an fs38 trimmer that someone left with me. Coil appears to be physically the same. Interestingly it has walbro stamped on it. I am wondering if it's worth time to install it and test. I did watch taryl fixes all replace a coil on what looked like a fs38 but he wouldn't give a part number. Said look ipl part number and get same one. What would likely be the difference between 2 stihl coils that were physically the same?

[bgsengine]

I What would likely be the difference between 2 stihl coils that were physically the same?

Pretty much anything and everything, from number of turns of the primary & secondary to the internal wiring, the transistors and controller chips (controlling timing, duration, etc) can create sizable differences in performance - which is also why "will fit" parts are often just that - they fit, but they don't necessarily work properly for their application.

However, Walbro IS known for manufacturing OEM ignition modules (they aren't just carburetors) so if you had a Walbro branded module that the Walbro part number cross references to the OEM part number, then you likely have the same correct module. So, if it is worth taking the time to swap modules and test, all depends on what you feel your time to do so is worth. If they seem to be identical in every other way that you can identify, chances are good they might actually BE identical (You could always look up part number for an FS38 module and see if it matches your FS36 ?)

[KE4AVB]

Wont work. FS38 is 4140 engine and the FS36 is 4130 engine. Different specs.

And on top of that the FS38 can use one of two different coils based the crankshaft timing which Stihl changed on later models.

[38racing]

Wont work. FS38 is 4140 engine and the FS36 is 4130 engine. Different specs.

And on top of that the FS38 can use one of two different coils based the crankshaft timing which Stihl changed on later models.

Had a thought, in middle of night of course. I think that I swapped shaft from donor to my neighbour. IIRC
my neighbour's was fs38 and it's his shaft on donor but I think donor might have been fs40. Hopefully I can find and read tag I had on it. Sellers were indicating fs36 and fs40 shared same coil. Update: no maybe it's fs44 that shares coil.

[KE4AVB]

To a point

FS36, 40, 44 share parts. 4130 engine.

and FS38, 45, 45 share parts. 4140 engine.

But not between the different engine series normally but the drive shafts will interchange they are the same diameter.