Is an OS #8 plug considered a long plug? Not quite sure what the term "long plug" means. Just want to make sure that I've put the correct plug in my TT 46 Pro.
Thanks

OS No. 8 has been like an industry standard plug. It literally works on all 2C engines. Long plugs have a longer reach, the portion inside the combustion chamber is actually slightly longer than a standard plus. This link is a good one to find out info about engine and props ... http://www.bolly.com.au/book/

The OS #8 is considered a long plug, and will work just fine in your engine.

I wouldn't consider the OS plug "industry standard" at all. It's a very common plug (and very expensive), but it's actually shorter than "standard" long plugs, so if anything it's an industry-non-standard .

I've never seen this be a problem, however. And I have seen an engine that had more-than-normal compression run better with the shorter plug. It's not unlike the old trick of putting two washers under a long plug.

Short plugs have a shorter threaded section. They are usually used in small engines that have a thin head, where a long plug would actually stick down in to the combustion chamber and cause problems. Unless you fly engines in the .15 and smaller range, you'll probibly never need one. (and most all the .15's I've seen use long plugs).

my little tower .15 wouldn't start or run on a long plug, but runs great on a short... reason is that I run 30% fuel, and the plug length was enough to push the combustion too high, the fuel was igniting WAY to early and it would run for a second or two if I was lucky. (fixed later with head shims, but it was a puzzler at the time...)

Did you try a cold plug? If you're going to really wind the engine up, you might actually look at some of the car racing plugs. Those things are really cold, which delays ignition. Most sport airplane plugs are on the warm side of medium for better idle at the lowish compression ratios we run.

Industry standard as in everyone uses it in almost every engine and hence, its 'standard'.

Hi Folks,

Like most I have used Fox (yeah I'm an old fart), Enya and OS plugs for years with the occassional Taipan for a bit of comic relief.

Is it just me? Lately I have found the newer OS plugs have a much shorter life than I was used to so I have reverted to Enya and Taipan exclusively with good results. Maybe OS are using coated platinum wire in the coils now?

winger 1955 I would use a hot plug in the TT for running in if it is a new motor (any metal particles in a new motor will lunch the plug) and then revert to the OS 8 or equilavent. Don't be afraid to experiment. I have an old motor that has to have a plug with an idle bar to function properly and a Fox 35 control line motor inverted in a Nobler that still runs well and must be thirty years old.

Cheers,

Colin

That's pretty funny. I'd term that "marking standard" or maybe "user standard" though . I haven't bought an OS plug in years. Actually, I take that back, I have a spare OS F plug around somewhere. I use them in my 4-bangers. But I use K&B plugs in my 2-strokes. To each his own.

OS plugs are probibly the most common plugs in use though.