stunthanger.com

Engine basics => Engine set up tips => Topic started by: frank mccune on January 04, 2019, 02:48:58 PM

Title: Using a short plug in place of the proper long plug?
Post by: frank mccune on January 04, 2019, 02:48:58 PM

        Hello All

         Is there any reason that I can not submit a short length plug in an engine that is designed for a long length?  These engines will only used for sport flying.

                                                                         Tia,

                                                                          Frank McCune



                                                                           

Title: Re: Using a short plug in place of the proper long plug?
Post by: Dan McEntee on January 04, 2019, 05:47:19 PM

  Running ashort plug will make the engine susceptible to flaming out at the wrong time.  The element is not in the combustion chamber where it should be to get the proper amount of fuel to fire. Bite the bullet and buy the proper plugs. They are cheaper than whole airplanes, sport flying or serious PA!
  Type at you later,
   Dan McEntee

Title: Re: Using a short plug in place of the proper long plug?
Post by: Dave Hull on January 04, 2019, 08:20:41 PM

You can, but you probably shouldn't, unless you are grounded until you can wangle some proper plugs.

If you are just doing straight and level-ish, then there isn't much risk. It won't do any damage to the engine.

But it will run cold because the plug element is buried in the head, and the compression will be slightly less. So if you have a choice of short plugs, run a hot one. (OS A3 aka #6).

Some engines may like it less than others. A Fox 35 on a profile doesn't sound good if you are going to try loops....

Divot McSlow

Title: Re: Using a short plug in place of the proper long plug?
Post by: Steve Helmick on January 07, 2019, 04:43:12 PM

We had a young feller in the club that was sold a short glowplug for his Fox .35 stunt. It ran very badly, with one click between run and not run. Without the battery, we had no luck keeping it running. I stuck in a Thunderbolt long idle bar and it ran like most Fox .35 Stunts; mediocre.  LL~ Steve

Title: Re: Using a short plug in place of the proper long plug?
Post by: Ken Culbertson on January 07, 2019, 07:10:27 PM

Quote from: Steve Helmick on January 07, 2019, 04:43:12 PM

We had a young feller in the club that was sold a short glowplug for his Fox .35 stunt. It ran very badly, with one click between run and not run. Without the battery, we had no luck keeping it running. I stuck in a Thunderbolt long idle bar and it ran like most Fox .35 Stunts; mediocre.  LL~ Steve

Is "Fox Derangement Syndrome" a recognized disorder?  Who can forget their first Fox 35.  Have some respect! LL~

Title: Re: Using a short plug in place of the proper long plug?
Post by: Steve Helmick on January 09, 2019, 04:01:47 PM

I'd rather have a Fox .29 Stunt...piston should be lighter, so a bit smoother. But the big thing is that the cylinder liner is significantly thicker and less prone to distortions. Cranks still fall apart, of course!  ;)  Steve