Glow plugs

[hederjr]

Ive looked through the forum and really culud not find the answer for this one. What does the number on the glow plug signify??? The reason I ask is I have two motors out of two seperate 1/12 buds. One had a r3 and the other an r4. I want to buy some spares. Ive read the forums looking for a replacement and it seems like everyone has there own opinon of what works. I also noticed that there are long and short plugs. What does it all mean??????? :confused:

[Ron Olson]

The number shows the heat range. Usually the higher number is colder. You want a hotter plug for low nitro and a colder plug for high nitro. Short and long tell you the length of the plug going into the combustion chamber. A long one might hit the piston in engines under .21 cu.in. so if you have those you'd want to add a plug gasket.

[quicklimegirl]

No plug will hit a piston.

[Ron Olson]

Evidently you're not familiar with those that put idle-bar plugs in boat engines because they happened to have some from their planes. Boats have a lower squish band area than plane engines so I see a lot of people that put these plugs in and wonder why they are having problems.

[bugfanatic]

A plug can't hit a piston? Seriously - who told you that? I've seen it & yes Ron's right, it can happen. Or more correctly, I've seen where a piston has hit a plug.

[quicklimegirl]

Read it in rcca magazine! Huh steve.