There have been several discussions of magneto lights over the years, but I'd like to get the latest wisdom on the subject, if there is any. My headlights have 1142 bulbs in them. That's rated at 12.8 volts, but I don't know how relevant that is since the mag voltage varies so much. Before I buy any more 1142 bulbs, I'd like to know if there's something else more suited to this use.
I've been using 1144 bulbs for years. They are rated at 16 volts.
I'm a bit surprised that Larry is the only one who responded so far. If I'd asked what kind of oil to use in my doctor's coupe the discussion would be a foot long by now.
(Message edited by steve_jelf_parkerfield_ks on July 13, 2015)
Why not buy magneto bulbs and use those? Bill Barth sells them at Chickasha every year, and there are probably many other sources. Millions were made and they are not rare or expensive today.
With all due respect to Royce comment...If you are using 1142, continue to use 1142!
What you lose against being 'pure' by using 12.8V lamps is the low end trigger point of the filament moves up to about 6V ea. (12V combined) to actually make incandescence. With original magneto lamps this was about 4.5 volts.
What you gain is that instead of turning into 'flash-bulbs' at about 22 volts, these will last well into maybe the 28-29 volt range before they risk going 'pop'.
Your mag voltage not only varies as you point out, but the voltage point at idle and the voltage point at say 1200 rpm will vary from car to car based on the health of the magneto and the gap spacing of the magnets to the spools. Therefore, the actual 'light' produced will vary and in the case of the 1142, the rated 21CP will not be achieved until the magneto develops 25 volts, wherever that may be. (With my '15, that would be about 28-30 mph.)
I run 9-10V rated NOS/MIB 2" Edison tip lamps in the '15, they show up on flea bay every now and then with numbers that make no sense, but then I never turn them on (I'm also a paradox...the OEM style lamp with the H lens! Someday I'll get around to having un-fluted glass cut and ground.)