If mileage is of any consideration, vacuum advance is necessary, and I don't know of any magnetos that had that feature.
I swear, there were only two in cupboard when I last checked... they breed like mice. All have since been refurbished and converted to suit GM Holden's grey motor (inline 6, 1948-1963... Aussie version of the stovebolt 6). Only one is an eight cylinder... it's still asleep in the cupboard. And yep, even the dead ones bite. Spin them up with your fingers, and you'll soon do the Scintilla Shuffle. Cheers, Harv
You are absolutely correct. First mini-bike at 12yrs old. Learned all about magneto spark, and proper way to kill it.
So explain the difference between the OAC and the OXC mags. I found my answer: Q. What is the difference between the OAC Vertex Magneto and an OXC Vertex Magneto? A. The OAC competition model is a self-contained unit and has an internal coil. Amperage for the OAC = 1.3 AMP. The OXC Super Competition model has an external coil and is used for more high output applications. Amperage for the OXC = 2 AMP. It is used for maximum voltage output with a long duration spark and has been designed for engines using superchargers, exotic fuels and high compression engines.
Interesting. The last four Vertex magnetos I had done up (old ones, as per the photos above, all internal coils) had the coils removed and replaced with new units. Nothing fancy. They pull 1.9 - 2.5A. The rebuilder offered an external coil conversion which would pull ~5A. Not bad for 1960's kit Cheers, Harv
I would recommend utilizing a separate kill switch for the mag, it has a few benefits that I’ve used multiple times.
If centrifugal advance is possible, it shouldn't be impossible to rig vacuum in some way. You could even be creative about locating the diaphragm canister.
For the sake of discussion ; I was told by Mallory tech 20 years ago that the mileage gain with vacuum advance was in the neighborhood of 10%+ - . For our cars , that's generally less than 2 mpg . Given the miles mist of our cars are driven , that savings amounts to a pretty trivial amount of money . IMO , hardly worth pursuing , or getting too concerned about . What say you ?
18 years ago we had Joe Hunt hop up a 1amp Mag to 5 by the magnets and an external coil. I still remember how much better GMC 6 ran. I still have 2-3 extra OXC coils.
G'day Lippy, I've not heard of a "big" Vertex cap before. I've seen the various coloured caps (see summary attached), though the design of them is all pretty similar. I've also seen the close-interference suppression caps. In this case the magneto was screened with a special metal hood and screened (braided) spark plug leads. This was referred to as “radio screening type LRO”. Do you have any details or info on the big caps please? Cheers, Harv
A big cap is done using Ford stock parts from a HEI type ignition for their 6 Cylinder. The adapter screws onto the mag and the cap clips on to the adapter. The rotor is the stock Ford. Joe Hunt did this on the mag we used in Joe Fontana’s 12 port GMC 6. They were light gray. Sorry no photos showing this. A Cardone 842669 for a 1975 E-100 van 300” 6 on Rock Auto will show the 6 cyl cap. An 8 cyl cap is available; but you can see the adapter.
Many thanks Jimmy Six - appreciated. If I've got it right, you purchase a full Cardone 84-2669 dizzy, as per below: You keep the cap and adaptor (labelled above) and the rotor button, but throw out the rest of the assembly. The adaptor mounts to the Vertex body using two of the mounting screws, circled in red above. Have I got this right? Anyone know if there is any additional machining involved, or if it is a bolt-up swap? Cheers, Harv
Being plastic & a consumable , I'd guess that cap & adaptor are available separately ... Edit ,86 - 93 mustang 5.0 ??
I hope so... I'd really like to give the big cap modification a try, and any way to make it cheaper would be good. I tried Googling through the Cardone website, but could not find the cap/rotor/adaptor separate. Cardone is not seen to often Down Under, so harder to rock up to an autoparts store and ask for their help. Anyone better at Googling know what the part numbers might be please? Cheers, Harv
Just saw this thread and will jump in and out. In the mid '70s I commuted 50 miles a day for at least 2 years in a 1957 Jaguar Mk I sedan running a Vertex Mag and Isky E-2 cams. Never touched it. It was solid as a rock up to 6000 RPM. Never even thought about a problem Just my info.
I have ran Vertex & Mallory internal and external coil's on street & Full race with 30 psi of boost , No issues, Most that try a Mag will not know how to start a engine properly.
G'day 19Eddy30, Most cars have some quirks for starting - richer, leaner etc, especially if they are fitted with old mechanical choke kicks/dashpots etc. The one magneto starting quirk I know of relates to fixed timing. If the advance weights have been removed (or were never fitted), the engine needs quite a bit of fixed timing to compensate. Lots of timing advance at low speed can make them painful to start (on a bad day, the poor thing can try to run backwards like an old kero tractor). To help starting, the maggie switch is left on (maggie grounded) until the engine is up to full cranking speed, where tolerance for more advance is higher. The switch is then turned off (maggie not grounded) and the engine fires. Any other magneto starting tricks to share? Cheers, Harv
Harv, that the main Key to starting a engine with a Mag , Separate Kill switch off , let engine get to a good cranking speed ,Then turn Mag on . Most will try to start with mag on , & then say ""Mags R Junk" witch is User error!!
Sorry Mike just saw this, I just used a piece of thick wall tubing I had lying around , just measured the coil and made it the same, you can leave the coil in and just drill right through it Sent from my iPhone using H.A.M.B.