Any advice on what kind of glow plug to use on a Thunder Tiger 91 four stroke that is going to be inverted?

OS "F" type, you'll love it.

I had good luck with Fox Miracle plugs. They ran great and lasted for ever in my inverted Saito 1.20. The also worked great in the K&B .65 that run super rich in the mid range.



Dru.

OS F

The following 4-stroke plugs have thicker filaments than standard plugs and will stay hot longer between ignition strokes:

O.S. F Type
Fox Miracle Plug
McCoy MC-4C

Nice choice on the TT F-91s by the way. I have one on my Ace Hobby Staudacher S-300 and it's a real honey of an engine!

I use OS "F" plugs in my four-strokes and Super Tigre "Medium"s in all my glow two-strokes.

I run all of my 4st engines inverted OS F plug

OS "F" without a doubt. Get 'em at Central Hobbies, $6.39. Tower's latest flyer shows them at $11.99!!!!!
Paul