ralph289

My rigger 3.5 Hawk OS .21RZ-M hauls BUTT but after ONE run, maybe 6 laps I found that the Glow Plug MC-9 wire coil was distorted AND Broke Any ideas..... TOO Lean ??? Running 60% nitro.

Believe It

either way too lean, or you are encountering detonation...

was the coil already a grey color after that 1 run?

ralph289

It was a brand new plug (first run) so not much on the coil but is broken, it ran back into shore fine but must have broken when it started to cool down I would guess. I'm thinking too lean also.
Thanks

wave waker

besides too lean it might too much compression in this case needs head shim...

ralph289

I just looked at the plug under a magnifiing glass and I can see some whiteness on the broken coil at the top. My old plug looks much better. I believe I went TOO lean. Think I will try 1/2 turn out .

Vertical3-D

My Feedback: (20)

yeah, white coloration is a sign of very high heat so too lean is the issue, as was also suggested another head shim may help...but Id try to richen it up first, no need to loose compression unless you have too

ralph289

Yes I believe I just leaned it out TOO much. Will richen it up and try again.
Thanks

jetpack

My Feedback: (1)

I'm going to call it as not enough head shim. You cant get much colder than an MC-9 plug, and if it kept you running through the run, and then broke at shut down...it got hammered with compression/scavenging. A lean run I am sure contributed to it, but thats not the whole reason.

Take note on your next start up after getting your needle set, and watch what happens when you take your glow clip off. If it sags even the slightest bit, your running too far into the cold heat range. If it stays steady and you are sure your rich on the needle and it still breaks, you have to call that problem compression.

Before you put the new plug in and run it, heat temper it five or six times with a good cool off period in between. This helps strengthen the element before it gets pounded by ignition. They used to put that on the back of glow plug packages, but somewhere marketing woke up and stopped giving that tip.

ralph289

Thanks, some good info.
Ralph

gooycheese

Ralph you lucky dog, this morning the temp is 19°f and will get up to 34°f . Wish I was in Florida in the warm boat weather


Paul

ralph289

WOW......19
Don't want to "rub it in" but going to the Lake today should be about 80 degrees at 1:00 PM, Fun in the Sun
Just have to pile on the sun screen.

goldendesign04

Way to go Ralph gotta love the sunny state![8D] here its 78F an only 9:30 am gonna run the SV27 before work!

ralph289

Richened it up 1/2 turn and ran GREAT, plug looks great too.
Maybe a little fat but that's ok for now. Head temp was only 127.
Thanks for the help.