Mecoa glow plug adapter head for TD09

balogh Sat Dec 16, 2017 10:35 am

This topic or a similar may have been posted here before, yet I write about it and ask for advice of anyone having the experience.

The Mecoa trumpet-shaped head with the glow plug (K&B 1L 7311) that Mecoa says performs well with it cannot make my TD09 with muffler spin faster than 15,3k with a 6x4 prop, when fed on 20% nitro. The engine ran hot so I added 1 then 2 more shims under the head with no apparent improvement on the rpm.

Mecoa glow plug adapter head for TD09 Mecoa_10

The stock COX high compression TD09 head easily revs it up to 19k under the same conditions.

Mecoa glow plug adapter head for TD09 20171211

I know the point is the glow plug that may emit more heat than the stock glow head and cause premature ignition thus overheating the engine.

Yet I ask if anyone has managed to approach the same rpm with the glow plug adaptor head as with the stock COX head, with how many shims, and what glow plug, and what was the difference between the two rpm-s?

Thank you.

Surfer_kris Sat Dec 16, 2017 11:48 am

This is an inherent problem with regular glow plugs, they simply seal in the wrong place and the threads of the plugs become a part of the combustion chamber. The only way to match the stock heads is to use the Turbo or Nelson style of plugs.

One thing you can try though is to seal the threads with high temp silicon, let it cure over night before running it. This trick has helped on .049 engines.

I cannot believe that anyone ever requested that type of head, when Valentine showed how one should do it.... Huh...

balogh Sat Dec 16, 2017 11:50 am

Thank you I would never have thought if this. Will try.

Surfer_kris Sat Dec 16, 2017 3:52 pm

balogh wrote:Thank you I would never have thought if this. Will try.

There is a good read about regular plugs here; http://www.rcuniverse.com/forum/1-2-1-8-airplanes-70/7973256-great-glow-plug-run-off.html

To make a long story short, regular plugs can be made to work if the threads are sealed and if the head has the right compression ratio.

balogh Sat Dec 16, 2017 4:37 pm

Thanks Kris very good reads. I can seal the threads but for me the only way of increasing compression further is removing shims from under the head

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Mecoa glow plug adapter head for TD09

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