Glow head/plug possibilities

Aero Thu Aug 21, 2014 11:35 am

I have been working on/cleaning/restoring several of my Cox and other small engines. Others being Norvels and an odd Wen Mac. Most of which are 049’s. I have been looking around at the glow head/plug possibilities. Since up to this point I have only used original Cox heads, I wanted to try the some of the available combinations of heads and adapters. I already have one of the purple RJL glow plug adapters and it will be the first one I’ll try to run. I was also thinking about ordering some of the button type plugs and clamp rings either Merlin or Cox to try out. I have been running Sig Champion 25 in the engines.
Just looking for any input from the gurus on the forum.
Also,
Are the various glow heads and buttons sold by the different dealers all made by the same manufacturer? I can’t see how there would be a dozen glow head/plug makers around the world.
If this stuff has been covered, and I missed it, please post a link…

pkrankow Thu Aug 21, 2014 11:52 am

There are a number of different drop-in style inserts. The different manufacturers use several different bore of clamping rings. As I understand it one can use a large hole clamping ring with a small post drop in insert. The rim is important.

I am sure that a close fit affects cooling. I do not know how it affects plug life.

Phil

Aero Fri Aug 22, 2014 12:35 pm

This is new territory for me. I have read that performance can go both ways. Kinda looking for some input on other peoples experience. I want to come up with a simple setup that just works.

Surfer_kris Sat Aug 23, 2014 1:53 am

Aero wrote: I already have one of the purple RJL glow plug adapters and it will be the first one I’ll try to run. I was also thinking about ordering some of the button type plugs and clamp rings either Merlin or Cox to try out.

The "adapters" from RJL that uses regular glow plugs are not worth the money. You lose a lot of power with those, this comes both from the regular glow plug thread and the large volume of the heads.
You need a head that takes Nelson or Turbo style plugs, if you wan't to use glow plugs.
The head inserts with clamping ring are all made by Merlin, as far as I know, so there are in reality rather few options, not counting the different heat ranges.

The inserts are high on compression, so you'll several head shims to get a proper compression ratio and it is also fuel dependent.

Aero Sat Aug 23, 2014 7:10 am

Thanks Kris
Thats the kind of info I was looking for. I was leaning toward the Merlin type plugs since they should work with the Cox and the Norvels I have.

Just need to figure out what heads will work with the other engines I have picked up!

**RknRusty** Sat Aug 23, 2014 8:24 pm

I like the Merlin drop-ins for my Cox and Norvels because they work great with my NiCd Dubro glow igniter.
Rusty

**Cribbs74** Sat Aug 23, 2014 11:42 pm

Nelson heads get my vote.

JPvelo Sat Aug 23, 2014 11:54 pm

The Merlin's are the most cost effective and work great. Power output is on par with a tee dee high compression head.
If you want all out performance definitely go with the Nelson. They may win in cost effectiveness as well, I've heard the plugs last forever. I only use them in my planes for the Reed speed contest so I haven't put that much time on one.

Jim

Aero Sun Aug 24, 2014 8:30 pm

Thanks everyone!

My son and I will most likely order some Merlin gear.

I did find a NIP 049 head while digging trough a collection of parts I picked up last year! Very Happy