Do coils come in packs of 1 or 2?

[LargemouthBass21]

those are great little motors if mechanically sound to start with (compression must be checked as indicated above….)


yet bad compression may be just a bad head gasket ($5-10)

why not go all the way if you fix the coils change all the plug wires & booths with new solid core metallic plug wires (no carbon stuff) small price to pay for peace of mind out on the lake

I replaced the head gasket alresdy when I cleaned out the water passages, my torque wrench didn’t have a low enough setting so I made sure to get them snug. Hopefully that isn’t a problem. Compression seems better than before it seems to pull over with a little more oomph (still won’t start). I need to order some coils...

 

[lindy46]

I replaced the head gasket alresdy when I cleaned out the water passages, my torque wrench didn’t have a low enough setting so I made sure to get them snug. Hopefully that isn’t a problem. Compression seems better than before it seems to pull over with a little more oomph (still won’t start). I need to order some coils...

Borrow an inch/lb torque wrench from an auto parts store and do the job right.

 

[Crosbyman]

measuring the coils is mostly informative but not a definitive test since high voltage goes where it wants to go.. furthermore the air thin wire could be broken and read OPEN on a meter yet the high voltage would still jump across the break to reach the plug… as I said its more informative than definitive. don't worry about it.

measuring coils tells you if you lost continuity between the boot and the HV winding in the coil… a symptom to investigate further when looking for bugs :spider:.

 

[LargemouthBass21]

pics of reworked magneto this is a 5.5 but 3hp's are identical

Those are some crunchy looking coils in the first picture, mine look the same but are green. Are most of the coils the same for the 50s-60s OMC? Mine is a 3hp ‘64 Yachtwin. I will definitely refer to your picture for reference

 

[LargemouthBass21]

measuring the coils is mostly informative but not a definitive test since high voltage goes where it wants to go.. furthermore the air thin wire could be broken and read OPEN on a meter yet the high voltage would still jump across the break to reach the plug… as I said its more informative than definitive. don't worry about it.

measuring coils tells you if you lost continuity between the boot and the HV winding in the coil… a symptom to investigate further when looking for bugs :spider:.

So I should just put em on and not worry about it?

 

[LargemouthBass21]

Borrow an inch/lb torque wrench from an auto parts store and do the job right.

I considered it, but I’m sure it’s tightened enough or maybe more than its supposed to be (not good I know) but I’ve read people saying they did a quarter turn past snug and their motors ran great. I did the crisscross pattern while tightening the bolts so I should be alright there.

 

[LargemouthBass21]

I would say replace plug wires and the plug -----" boots " too.-----Make sure you get plug wires with a METAL core !

What exactly will happen if I use some ‘carbon impregnated’ core wires. I believe there is SOME kind of metal in there as carbon is most definitely not a conductor. I have some nice 7mm automotive wires already and they have boots installed and everything. I have read around and there are lots of people that say it works to use cored wires. Mine say impregnated which I take to mean that it is not solely one material, but a combination of something else as well. Hopefully I can use these and not have to find something else.

UPDATE: I noticed the wires say Low Ohms on the side, which I take to mean low resistance. Will these wires be okay to use?

 

[kbait]

If you use carbon core auto wires, they will fail quickly. You need plug wires with metal core - like original..actual wire inside.

 

[racerone]

And why do you say that carbon is not a conductor?----Where did you read that ?

 

[Crosbyman]

carbon will conduct no doubt about it gazillions of motors run with carbon brushes.

as to coils.… unless proven good ………...and two miles out is not the place to find out they were bad…


you indicated yours are green…. are they cracked or not ??? greens should be good and were likely installed few years back……. but good nonetheless !

But if you do see cracks they need to be replaced and in so doing redo all the wires and boots with wire core. OMC magnetos are not modern car ignition pushing 40,000 volts . with wire core the only resistance to overcome will the plug gap .030.

I purchased a few sets of old stock carbon core wires for next to nothing stripped the boots and reinstall them on wire core .

I have installed the cheap chineese coils from EBay and did not have any issues creep up on me yet. your call !

 

[Tim Frank]

I considered it, but I’m sure it’s tightened enough or maybe more than its supposed to be (not good I know) but I’ve read people saying they did a quarter turn past snug and their motors ran great. I did the crisscross pattern while tightening the bolts so I should be alright there.

I have never seen a spec for torque on a head bolt as "tight enough". You may only end up with "almost enough " compression.
Many of us are still curious as to compression reading....what probably should have been step one....i.e. before spending 100s of $$.
.

 

[LargemouthBass21]

I have never seen a spec for torque on a head bolt as "tight enough". You may only end up with "almost enough " compression.
Many of us are still curious as to compression reading....what probably should have been step one....i.e. before spending 100s of $$.
.

I do not own a compression tester, as I said earlier the rings and cylinder walls are good, and the bolts are very tight, if the reading is out of spec, it would only be because it is high.

 

[LargemouthBass21]

And why do you say that carbon is not a conductor?----Where did you read that ?

Chemistry? Let me rephrase that, most carbon forms are not known as being GREAT conductors.

 

[LargemouthBass21]

carbon will conduct no doubt about it gazillions of motors run with carbon brushes.

as to coils.… unless proven good ………...and two miles out is not the place to find out they were bad…


you indicated yours are green…. are they cracked or not ??? greens should be good and were likely installed few years back……. but good nonetheless !

But if you do see cracks they need to be replaced and in so doing redo all the wires and boots with wire core. OMC magnetos are not modern car ignition pushing 40,000 volts . with wire core the only resistance to overcome will the plug gap .030.

I purchased a few sets of old stock carbon core wires for next to nothing stripped the boots and reinstall them on wire core .

I have installed the cheap chineese coils from EBay and did not have any issues creep up on me yet. your call !

Mine are green and very much cracked. They worked recently (good blue spark in both cylinders) but Something happened and I no longer have consistent spark. I was moving the plug wires around, perhaps they cracked internally. As long as I have the flywheel off I will replace the cracked coils as well. Glad to hear I can just buy the cheapo coils. I found 2 for $25 with free shipping (ships from Hong Kong). I called up my local auto parts store, they do not carry copper core wire. I found some on eBay for 1.25 a foot. Does that sound like an ok deal/look like ok wire. The reviews look decent. https://www.ebay.com/itm/7mm-COPPER...416766?hash=item2a7cbd723e:g:G5UAAOSw2gxYv5bv

 

[lindy46]

Wire is correct. Coils? You get what you pay for.

 

[racerone]

Offshore manufacturing is done in a " near zero tax " environment---------I see a new STIHL chainsaw on TV for $199 and wonder how that is done.-----Your local chainsaw dealer would charge more for a new chain / bar and tune-up on your old saw.-------So go ahead and use the coils from Hong Kong.-----They likely will meet all the specs just fine.

 

[Crosbyman]

Chineese coils are slow to arrive….. I always have a spare set or two

Don't expect fast delivery so in the mean time start working on the rest you have not done yet

take you mag plate out clean and lubricate where need be ….etc...

do not reinstall your mag plate since you will need to "screw" the wires into the coils install the little protective boots and a dab of dielectric grease

I like to protect the new wires with plastic sleeves

 

[Tim Frank]

Has this motor started and run since you found it?

 

[Crosbyman]

Chemistry? Let me rephrase that, most carbon forms are not known as being GREAT conductors.

[COLOR=rgba(0, 0, 0, 0.92)]"Graphite has many forms and uses in our everyday life. Natural graphite can be found in China, Mexico, Canada, Ukraine, and Brazil, and it is used as a lubricant, filler for flexible graphite, artistry tools, KEVLAR, and of course, pencils. It has a very low resistivity ranging from 9 to 40 µΩm. You could say its resistivity is effectively zero" [/COLOR]

 

[racerone]

Are you saying that graphite / carbon is a good conductor ?