TOPIC: Looking for ideas - Bendix-Scintilla magneto

I have a Mark 20, with a Bendix-Scintilla magneto.
The coils are after-market dated late '90s.
The points are polished and are contacting pretty straight.
The condensers don't appear to be original and I don't know if they are the correct value.
I have tried several other condensers from Phelon magnetos, but still no joy.
The high tension leads look fine, and I am unable to see them arcing to ground anywhere in the dark.
The magnet is strong enough to lift a carpenter's 'wonder bar' a pry bar made out of flat spring steel.
The key is good.
With the points set at .018" the beast has fat blue spark, but only to about 1/8".
If I set the gap to .010" the fat blue spark jumps a wee bit more, maybe 5/32" (wahoo - NOT)
Any ideas????
Tomorrow I try a set of old original B-Scintilla condensers, and my last (2) sets of used points, and last ditch,...I will dig out a set of NOS coils I've had in my sock drawer since they were new.
I'm hoping that one of you guys spot something I'm missing so I won't have to break out my sacred stash of coils.
Thanks,
Thom

Today I tested everything with my trusty old-school Mercury Magneto Analyzer.
Everything seems to test to specs. The condensers were faulty, but a set of used original Mark 20 condensers passed the tests, so I installed them.
The spark test through the analyzer showed plenty of spark jumping, even though my home-made spark tester still only jumped a fat 1/8"?
I installed a set of new J6c spark plugs and a shot of carb cleaner, only to get a few unexciting poofs (not even worthy of being called a few 'pops').
Still no Mercury Magic. SIGH-H-H-H
Definitely have a seriously sore elbow joint though, from pulling on the starter rope.

Thom

Hey Doc,
I had a KH7 Cruiser with the Bendic Skinny on it and it, too, dogged me for half a summer with a dead cylinder. It would show spark on both, but only run on one consistently. I'd futz with it, give up, come back to it a couple weeks later and give up again. Eventually discovered the issue was NOT ignition related. Bad upper main seal! It wasn't drawing fuel to the top cylinder, mimicking low spark in that hole! Might be worth a look-see...

Also, the magnet to laminate clearance is critical on those. Might look for excessive gap on one side or the other...

Hi Thom, I would be happy to send you another set of points and condenser, I switched my mark 20 to a Phelon ignition. The problem you are having is not unusual. Sometimes it is wear on the crankcase top where the stator rotates. If it is looser on one side than the other you will have a heck of a time setting the points. The scintilla coils are a fairly low voltage coil and the magnet really needs to spin fast past them to get a decent spark. I have a super rotor that I can send you if you like, has an extremely strong magnet in it, or you can replace the magnet yourself. Let me know if you want details.

K series flywheel type magnetos having contact
point opening .018” stamped on stator plate should be set to a basic clearance of .015”. A tolerance of
± .003” is allowable. The .018” stamped on the stator plate is the maximum point opening and should not
be exceeded.

Thom, the above is from a scintilla factory document back in the day. As you noticed, reducing the point gap to .015 is actually the correct setting, but only for those mag plates stamped with an .018 on them. Gotta love early mercs.

Thanks Scott & Dave!
I too am concerned that perhaps my issue is bad crankshaft seals.
While I had the magneto off the top seal appeared to be flexible, but I put a layer of grease on it to see if I could then get a pop or two out of #1, but no joy.
I don't see how to adjust the gap between the magnet & the laminates as the laminates are factory riveted to the stator plate.
Thanks too for the factoid that I can narrow the gap to .015".
I want to take a closer look at sideways movement of the stator plate Dave, but I might just take you up on your offer to send me a good magnet if all else fails.
I have another stator plate if I find this one has sideways movement.
If I master this beast, I have another Mark 20 & a KH-7 cruiser I just snagged that will probably have the same issues.
Dave,...Where did you find a Phelon stator plate & small taper flywheel that will fit a Mark 20??
I would LOVE to convert to a Phelon, but don't have a Mark 15 or know what other Merc would have the same style Phelon system.
Thanks guys! Looks like I have some 'homework' to do.

Thom

Thom I think I snagged the last one in the USA LOL. I got it from a dealer in Minnesota, he sent me the whole thing, flywheel, points cam, stator plate nuts bolts screws brass retainers 2 new coils. All for $80 to my door, and you know how far away my door is from Minnesota.

The method for adjusting the laminated poles is as old as time. HIt it with a hammer. Little taps and measure the gap with a non ferrous feeler gauge.

I will make up a care package and send it your way anyway.

the rotor I have is a super rotor that I installed N48 rare earth magnets in. Definitely stronger.

Thanks Dave!
You are the MAN!!!

What should the gap be between the laminates & the magnet??
I will ,...As 'The Rock' used to say,..."Layeth the Smacketh on it" once I know the gap specs.

I spun the beast over with a gear reduction 1/2" drill motor I've used in the past while trouble-shooting when a simple rope pull wasn't cutting it - usually due to weak magnets or compromised coils.
The Magneto produced about 1/2" of spark when allowing the spark to jump to the DSH from the sparkplug boots.
I'm going to put the sparkplugs on each lead and see if the plugs' resistance will still allow a decent spark, but I need to wait a few days for my carcass to stop hurting so bad from the last 'round' with the monster drill motor.

Thanks again,
Thom

I finally decided to surrender and tear the beast down in hopes of finding something wrong.
AND,...
Like magic,....I found it!!!

Upon reassembly, the beast started with the first pull of the rope.
Runs a wee bit ratty and it sounds like maybe one cylinder is intermittent, but it runs.
Now I need to R&R the lower unit & impeller so I can run the beast long enough to work out the bugs.

Then,...There are (2) more tired old B-Scintilla fired Mercs awaiting their turn. SIGH

The attached pictures show what I found inside.
Doc

OK Thom, I have stared at those two pics and for the life of me I cannot see the difference. Give a guy a hint.

is it just me or was it, that case gasket blocking the ports?

Yes it was!!!

I have to wonder just how long ago some knot-head made & installed that gasket.
It was bought off EBAY a few years ago as a running motor for way too much loot, and the purchaser was never able to get it to run.
If the seller put new rings in when he replaced the seals, etc I'll bet that between his and the purchaser's team repeated cranking via the rewind or starting cord on the flywheel the rings are probably just about broken in.

I know I whipped the beast over O'Plenty too.

Once my shoulder & elbow heal from all the roping & use of my monster electric drill to spin the beast,...I'll be installing a new impeller and putting the lower unit back on so I can run the beast a bit longer so I can determine if she is hitting on both cylinders. Doesn't really sound like it is at the moment, but at least it starts and runs until I shut it down before things get too warm.
Thom

Now that I know what the difference is it jumps off the page.

THom I too own a nasty mk 20 that wont run I need a pair of coils and the prop wont come off its a free one though It came under my first 3s deck and its my last green merc at one time a had a mk40 kf9 with stacks and the 7.5 and the comet3.9 by the w ay I use a tall drill press and run the belt to the engine so i dont have to pull the ropes all in green all runners the stacks where cool and not too loud?