Replacement spark plug?

[SmallHaul]

I have been running my hit and miss engine for a while now and i just pulled the plug yesterday because it wouldn't start (found out that one of the coil wires was broken off and i fixed that) and was surprised to see that is is partially burnt?

I know that i did this because the plug looked perfect when i got the engine. I am running coleman fuel with a little wd40 mixed in. Have i been running it too lean?

Where would i buy a replacement plug? It is very long,.i haven't measured it but, the threads are about 1 inch long.

 

[10K Pete]

Try these:

http://www.daledetrich.com/spark_plugs.htm

http://sparkplugs.morrisonandmarvin.com/

Pete

 

[SmallHaul]

Pete, i looked through those links and didn't see any crazy long ones like the one in my engine?

 

[Cogsy]

Looks like that one may have been homemade. Not overly difficult to make if you've got a lathe (and a mill is handy to make the hex but you can file it).

Actually, since you've already got the body and I assume the insulator is corian, you could recondition the one you've got. Still need a lathe for turning the corian though.

 

[SmallHaul]

Hmm.. after looking through build threads on this engine (1/3 associated hired man) there is about .800 distance from the head to the inside of the cylinder. After learning this and looking closer at the plug i think the guy that made the engine also made the plug.

I will search for plans and maybe make an extra plug for it. I might even be able to take this one apart and replace the delrin core, if that it what it is made of.

Does anyone have any idea what would cause the plug to burn like it did?

 

[SmallHaul]

Looks like that one may have been homemade. Not overly difficult to make if you've got a lathe (and a mill is handy to make the hex but you can file it).

Actually, since you've already got the body and I assume the insulator is corian, you could recondition the one you've got. Still need a lathe for turning the corian though.

Thanks, i just submitted my post and saw yours... i do have a sherline mill and lathe and also a HF 7x10 so, i could make another one.

 

[10K Pete]

Wow. Couldn't see that from photo! The guys have it right in that you'll
have to make your own.

I didn't know that Corian could be used for this kind of thing!!

I learn so much here,
Pete

 

[stevehuckss396]

I will search for plans and maybe make an extra plug for it. I might even be able to take this one apart and replace the delrin core, if that it what it is made of.

Does anyone have any idea what would cause the plug to burn like it did?

The insulator material may not have been suitable for the use. If you can get hold of some Corian use that. It is a Dupont counter top material. I have plugs that are 5+ years old and still working perfect.

 

[SmallHaul]

The insulator material may not have been suitable for the use. If you can get hold of some Corian use that. It is a Dupont counter top material. I have plugs that are 5+ years old and still working perfect.

I have a friend that owns a granite company he might have some corian.

Hmm.. would granite work? It sure would look nice.

 

[rklopp]

Hmm.. after looking through build threads on this engine (1/3 associated hired man) there is about .800 distance from the head to the inside of the cylinder.

I run my Hired Man with a normal commercial plug with a ceramic insulator. Having the electrode recessed way up inside the hole in the head does not seem to bother the engine. Perhaps yours got too hot by being too close to the fire, so to speak. Corian is essentially acrylic plastic filled with rock dust. Think plexiglass. Corian can take more heat than straight acrylic by virtue of the rock dust, but only to a point.

 

[WOB]

Can you counterbore the plug hole for something like the Rimfire VR2L? That would be the best fix by far.

WOB

 

[SmallHaul]

I run my Hired Man with a normal commercial plug with a ceramic insulator. Having the electrode recessed way up inside the hole in the head does not seem to bother the engine. Perhaps yours got too hot by being too close to the fire, so to speak. Corian is essentially acrylic plastic filled with rock dust. Think plexiglass. Corian can take more heat than straight acrylic by virtue of the rock dust, but only to a point.

Do you know where your timing is at? I am curious if you have it advanced more because of it?

Can you counterbore the plug hole for something like the Rimfire VR2L? That would be the best fix by far.

WOB

Good idea. I might consider that if it doesn't run well as is with a normal plug.

 

[rklopp]

I don't know the timing on my Hired Man. I made it easily adjustable by moving the Hall sensor relative to the magnet on the cam gear. I seriously doubt the timing is affected by the spark electrode being up inside a hole, because the flame propagates really fast, like a good fraction of sound speed but not quite.

 

[SmallHaul]

I don't know the timing on my Hired Man. I made it easily adjustable by moving the Hall sensor relative to the magnet on the cam gear. I seriously doubt the timing is affected by the spark electrode being up inside a hole, because the flame propagates really fast, like a good fraction of sound speed but not quite.

Makes sense. Thanks for your input, i will order a normal commercial plug with a ceramic insulator and see how it runs.

 

[SmallHaul]

Just thought this was interesting because of the discussion of spark plugs in hit and miss engines... found this hit and miss engine running on youtube and the spark plug is out the combustion chamber and is attached to an elbow! And runs well:

[ame]https://www.youtube.com/watch?v=NY51fk_2FYU[/ame]

 

[SmallHaul]

Thanks everyone for the help and advise.

I got the The Rimfire VR2L Spark Plug today and the engine runs the best it has ever run.

I have seen a lot of full scale hit-n-miss engines fire twice on the hit stroke and my model engine always did the opposite and would miss twice occasionally if the needle wasn't set just right. Now with the rimfire vr2l plug it occasionally fires twice on the hit stroke and is so easy to start now. It fires right up every time now. The needle valve setting is much less critical now too.

Thanks again,

Scott

 

[SmallHaul]

It runs really well with the rimfire plug.

Thanks for all the help Fellas.

[ame]https://www.youtube.com/watch?v=BOMi7d4wRDA[/ame]

 

[xpylonracer]

Great looking and handling engine, really runs well.

Emgee

 

[SmallHaul]

Great looking and handling engine, really runs well.

Emgee

Thank You very much. My good friend Earl Walters built this engine and i am honored to own it.