Good input Robert. I will simply keep my dry coil and mount it away from the engine fan and keep the Bosch for appearance.
But that involves extending both the + and - wires from the Magna Spark to the coil and the coil wire to the cap. I mean a considerable extension (~24" ).
I am assuming line length is not vital here.
MotoCarlo posted:Good input Robert. I will simply keep my dry coil and mount it away from the engine fan and keep the Bosch for appearance.
But that involves extending both the + and - wires from the Magna Spark to the coil and the coil wire to the cap. I mean a considerable extension (~24" ).
I am assuming line length is not vital here.
On my previous motor I had the dry pack coil on the left side of the engine bay with 20" or so leads and had zero issues.
I did the same thing with an original Magna Spark (MS) and the accompanying large, original MS coil (a dry-pack) that just begged to be mounted on the left wheel well panel to un-clutter the engine. It has lasted very reliably for 20 years now.
I’ll do the same with the MS II dry-pack coil (only slightly smaller than the original but with no big mounting frame around it) if for no other reason than to keep it away from direct engine heat to protect it longer, just as I did before.
The length of both low-voltage-side wires (12 volt) and high voltage wires (coil-to-distributor) are kind-of irrelevent in our use, unless you run a 6 foot wire from coil to disti or something (and even that would be OK, but silly).
In my experience, oil-filled coils last longer than dry-pack versions, but that time frame is decades for both so probably not important here. What IS important is two things:
1. That oil filled coils can tolerate engine compartment heat soak (temperature rise after engine is turned off) better than dry pack, so keep either away from heat generators (like exhaust systems under the tins or the coil bolted to the engine case). Give them both a space that allows air cooling.
2. Automotive coils vary in primary (12volt) resistance from about .32 to about 3 ohms and are usually marked with their resistance (but not always). The coil primary resistance must be matched to the design of the trigger, whether points or electronic, because the trigger is designed for a specific current range. Mis-matches can result in damaging the trigger or producing an irregular spark, especially with electronic triggers (as the circuit freaks out).
Oil filled can also generate slightly higher secondary (output) voltages than dry-pack for the same primary side while still managing the heat, but that probably doesn't apply much for us, because our coils cluster around narrow ranges (40K to 50K volts) and the heat soak might not be as deep or long as with a water cooled engine.
One last thing. Comparable wet and dry coils will generate the same amount of heat while operating, but the wet version will dissipate that heat more efficiently by transmitting it to the surrounding metal can and then to the air and the can has more surface area than the dry coil.
It is also important, in our ignition systems, to use a coil designed to NOT use a ballast resistor. Our systems want a coil that runs on a full 12 volts.
Fantastic info Gordon. Thanks.
I have an MS II with the dry pack coil and Chinese tach. No problems for 4 years.
I am currently side-lined, waiting for a marine-style power buss to come from Amazon. I should have used one when I installed the original coil but I was young and stupid back then so I'm correcting knumb-headedness now. It should be here mid-week and then I'll have a moosey (10 ga) ignition wire from the fuse panel to the engine bay which will now be properly distributed to things that need it, like the oil cooler fan, back-up light, coil, etc. - All the stuff that should go dead when the key is turned off.
Mechanical layout looks good with the dry-pack coil right where the old (also dry-pack) coil was, and I've extended the disti wires over to where the coil is.
So......Sitting here twiddling my thumbs and waiting for the Amazon folks to show up, but it's warm out, so while it's up on jack stands I can spiff up stuff underneath for the season. That's the word from Backyard Engineering.........
Attachments
I'll bet you're wondering about that past bout with knumb-headedness.
How does three 14 ga wires crammed into a yellow (10 ga) fast-on tab and crimped (poorly) with waterpump pliers sound?
Yes, it worked, but not especially cool.
Plus, when I grabbed the fast-on tab from the 10 GA 12 volt feed coming from the fuse panel, I could pull it off the wire with my hands. Good reason for getting a ratcheting crimper later on in the build - WAY more professional and much better crimps. Thanks to the old-timer counter guys at "Fleet Maintenence" for telling me crimps made with waterpump pliers don't hold worth a Tinker's dam and "Buy this expensive crimper and smile for the rest of your build". Gotta love the old-timer counter guys in parts stores.
Well, after messing with my neighbor’s tree I was out in the garage and tried starting the car with the new ignition. It turned over really hard but eventually caught and started. I later put a timing light on it and found that the idle timing was around 50° BTDC. No WONDER it started hard!!
Once I got the timing set right it idles and spins up just fine. Soon as the rain lets up I’ll do a road test.
These cars always run better when the timing is within 40 degrees of where it should be.
Yah think??
I was pretty careful when I installed the new disti but probably got the before and after top dead center messed up (it’s easy to do that when you’re 69) but whallaheck...... It was easily fixed once it fired up. Runs one helluva lot better when the timing is right, too!
The MS II has an interesting-looking advance curve with a couple of subtle steps. I’ll have to map it out when I get the time to see what it looks like for real.
I’m always surprised to see the idle change for the better after the first two minutes of idling/warmup.
My "duh thing" was I had the #1 and #2 cylinder wires reserved. What was I thinking!
I have done this a million times... just a brain fart. The thing did crank, but it was not happy. So ... of course the thing I was sure to not do - I did. Weather getting better here. Hope to try it out this week - with wires in correct location and timed correctly.
Duh!
In college I had a summer job for a few years driving new school buses from North Carolina to Massachusetts. I picked up a brand new bus once, based on an International Harvester truck chassis with a 440CI V8, that literally could not get out of its’ own way. Eventually figured out that the plug wires were totally wrong - GM pattern versus IH pattern. Once I got that sorted out it ran like a champ!
Ok : 2 more questions. Does the coil hold a charge like the battery ? I a leaving my old coil on the fan shroud for appearance and just am curious.
And timing - my notes for this engine say 32 degrees btc at 3k rpm. And that is where I have time it with the original distributor and coil.
Is that correct for the Magnaspark too?
I read the Magna instructions, and it seems they are mostly aimed at adjusting the spark. The MS comes with the 20 degree advanced bushing and the medium springs. That will be fine for my 1835 engine... but unless I am having another duh moment (They seem fairly perpetual these days.), I just don't see a timing degree mentioned.
Huh? or Duh?
Motocarlo, no, coils don't hold a charge. Capacitors hold a charge, but, even so, the capacitors used in ignition systems (where they're usually called condensers) aren't large enough to be dangerous.
And common wisdom usually says to set maximum spark advance to 32 or less. Which distributor you use won't affect that prescribed limit. Some say to stay below 30 degrees to be safe.
The danger is that too much spark advance can make the heads run hot, with nasty consequences for the exhaust valves, even though the engine might sound great there - for a while.
Camshaft overlap, compression and combustion chamber design will determine how much spark timing you can run. On a typical 9-1 compression 2110cc engine with a moderate cam, CB #2242 or its equivalent Engle 120 and Panchito heads, I can safely run 34 degrees advance with no issues.
Thanks Sacto and Pat.
Mine is a mild 1835 - so I will play it safe at 30 - 32. I appreciate the quick responses.
So far , I love the MS, Pat. Well thought out and well built. Touch the ignition and fires right up. Plan to take it out for a run around the mountains this week. Thanks. With my new sidewinder exhaust - wow what a sound.
Sacto - I remember getting a nasty shock from a capacitor from an electric motor when I was a kid, so learned to ask these things. :-)
Thanks again guys!
It's shocking how much of a charge a capacitor can hold.
