Coil Swap for an Engine Test

[boovuc 1,090]

Hello again, Guys!

(Boy I'm in the electrical forum a lot these daze)!

I picked up a freebie 312Auto that was rode hard and put away wet way too many times! The tranny pump is gone, (Eaton 700), and it is an overall mess. The PO told me that the motor is good however the coil was removed for "another project" so I couldn't fire it up.

She is a K301S needless to say with a spec of 47829 which is what should have been on it. Now...I have a coil from my K181 857 that I thought about using to see how this engine actually is but my 8HP tractor has points and I don't see points on this 312-Auto. (Just the capacitor).

I know that there are differences between breakerless and points/condenser ignitions and the coils they use.

Am I missing where the points are on this newer 312-Auto or is this breakerless?

Can I use my coil from the old Starter/Generator equipped 857 to test this motor?

Will I finally find happiness and inner peace?

What are this evening's Mega Millions winning numbers?

There. That should cover it!

Thanks,

[B-100 Dan 7]

I really don't know the answer to that question, but I'm sure "Save Old Iron" will. I have seen pictures of coils with the tops blown off because they were the wrong ones for the application they were being used for. I would use caution until I found out for sure. Good Luck.

[Save Old Iron 1,563]

A condenser hanging off the tins suggests it is a coil based system - but it could be a botched conversion attempt.

 

Coil based ignition would have a set of points / points cover in the "classic" location for the K series engine (fuel pump, then cam cover, then points cover).

 

Oddly enough, the spec # you list shows both options available - breaker-less and points. The demystification guide shows a 1986 312-A has a points based ignition.

 

If it is a breaker-less ignition, there will be a small trigger box near the top of the flywheel with a wire leaving the trigger to connect with the breaker-less version ignition coil. The trigger box will be fed off a second wire going to a charge coil on the stator.

 

Sorry for the non answer but check again for the points cover - if it's not there, check on the flywheel for a trigger box - and while you're in there - pull the flywheel to confirm what amperage stator is present. If there is a charge coil on that stator, it's for a breaker-less ignition.

 

This is why I don't have a great understanding of the 300 series - always something going on with different "versions" of ignition systems and charging systems. Surprises at every turn with the 300's.

[boovuc 1,090]

Tell me about it! I saw both ignitions on the PartsTree view and wondered on the side of caution. I found the points cover and they are in there and actually not in too bad of shape comparing them to the rest tractor. The once chrome canister muffler was blocking my view. So I have a breaker ignition. I'll "assume" I'm good to swap the coil from the 857 to see if this puppy will fire and run without killing all flying insects within a 100 yard radius? The 857 has it's original breaker ignition.

[Jeff-C175 7,195]

 

I'll "assume" I'm good to swap the coil from the 857 to see if this puppy will fire

 

Not gonna mention the cliche...

 

Does the 857 have a ballast resistor in series with the coil primary?

 

If so, I wouldn't try it... you could burn up the 857 coil.

 

If not, probably safe.

[boovuc 1,090]

I think I'm good. Both tractors are + back to the key switch and - from the condenser and points.

No resister in either tractor unless it's up under the dash which I doubt. I think on my day off I'm heading to camp for awhile then come down and see if the term "nothing is free" holds true!

Thanks!

[boovuc 1,090]

Success! She fired up without any smoke at all. Runs smooth considering the old gas I had in the 857. (Pulled the 857 beside it and used the fuel tank from it).

Even took a video of it. Now to get it off the frame and on the bench.

Thanks for the hand holding!

[Jeff-C175 7,195]

Good deal Boo!

 

 

Even took a video of it

 

Can we see?

[boovuc 1,090]

Too large a file to post (MP4 format). I tried but hit a wall. 52 seconds at 44 meg!