I just ran my Savage 25 through about 3/4 tank of 20/12 fuel with a new plug and it finally died at the 3/4 mark. I checked the plug and sure enough it wouldn't lite. Both needles were set to about 3.5 turns out and I later opened the high speed to about 3.75 turns out. The glow plug was also not burned up. Any idea what is causing these things to die so quickly?

Ian

I have the same problem with my Rc10gt plus rtr.They are 6 bux a peice here and I get one every other day!.

Glow plug 101
This will explain things, you may be using the wrong plug
http://www.rcnitro.com/rn/articles/glowplugs.asp

Which plug are you using?

I run #8 os. or A3 os.

yeah those are the two i use on my rc10gt too. i'm ordering my savage 25 tomm and i think i will use os 8's in it.

I'm using factory HPI plugs so its the right plug for sure and I've read that article before and as good as it is, it doesn't help me. Thanks.

Ian

Just because it came with the engine doesn't mean it the best plug for your application.
The A3 and #8 are on the hot side of the OS chart, those are for lower nitro applications
I'd try a colder plug

So what does the plugs filament look like when it comes out of the engine?
Is the filament deformed smashed, or broken? That can happen when using a hot plug with high nitro and a high compression or new engine. You may be getting pre-ignition, this can smash the filament

Is it whitish and no longer shinny? that would be a sign of over heating and a lean run

I use a MC-59(medium heat) in my small .12 engines on 20% nitro
And a MC-9 (cold) in my .21 engines on 30% nitro

I've never had one of these go bad prematurely

Scale Only for me - then what plug do you recommend?

Ian

Ian.
I'd be happy to give you the benifit of my experiance but your not answering my questions
I suspect you need to run a colder plug, but that just a quess, not knowing what it looks like

Does your engine seam to have allot of compression?
What doest the plugs filiment look like when it comes out of the engine?
Do you have a temp gun? what's the engine running at?

Try running a cold plug, McCoy mc-9 or OS A5 or R5

OS chart


McCoy chart

I'll have to get back to you on the filament but its definitely not burned up for sure

Ian