Kind of depends on which sparky. Atwood Super Champs, Anderson Spitfires, and McCoy 60's, will all run well on glow. Super Cykes, Ohlsson's, and most others will run well, but don't last to long. Cykes and Ohlsson's, will beat out the front bushing pretty quick. As for fuel, I would run at least 28% oil, with mostly castor. They all run fine on ignition with glow fuel if you keep the nitro at 5% or lower, and keep the timer retarded a little. Forster 29's thru 35's will also run fine on glow plugs and glow fuel. Just my 2 cents, and others may say different.

Kind of depends on which sparky.

Brown "D", and a rather ratty one too! And it's going to be run on glowplug, at least to begin with. Prop is a KK 14 x 6 Truflex.

Thanks everyone so far, any more contributions?

Floyd et al - o.k. here's the story. way back in '56 as a 16 year old, I had come by a "B" (lapped piston?) Brown. I also posessed a 1938 Zaic year book, in which were details of the Carol Krupp 1937 Bowden Trophy winner. I decided I would enter one of these aircraft 20 years later, in 1957.
That year they decided not to have the contest any more, as interest had dropped off too much.
The Bowden has now been resurrected and is flown to similar rules (I think). A new stipulation these days is that models must have a cockpit.
I have now come by a 1937 Krupp model in a trade. My "B" Brown is long gone. No time to sort out the sparks, but the ratty old "D" Brown (ringed) I now own is showing signs of being a runner on glow! Yesterday I ran out some primes on 75/25 o.k. and also on 75/25 IPA/Castor, but the plug needed to stay connected. Today I got a tank attached and got consistent runs on 75/25 and 50/25/25, methanol/ipa/castor. I agree the Brown parts look weak, the wrist pin looks frightening! Next run I'll get a tach on it and check the revs.
If I can get it even semi-sorted in time I'll have a go at our f/f Nats in two weeks, 74 years later. If it leaves the ground I shall have fulfilled my ambition! Maybe I should wait till next year, 75 years? And 55 years after my first intentions. I have a cunning plan to meet the letter of the law concerning cockpits/pilots.