Wen Mac Plug Tests

Over a couple years, I purchased 8 Wen Mac Mk XII, Mk XIII and Testors/McCoy .049 engines from eBay suppliers and at swap meets. Many of the 'Rotomatic' starters were broken, plus the starters are all steel and add considerable weight to the engine. Given these factors I removed the starter assemblies and installed Cox thrust plates.
These engines have been out of production for a long time, so the glow heads are not easy to obtain. Merlin produces an excellent 'drop-in' style glow plug for Cox and Norvel engines. These use a head clamp to secure the glow plug. I machined a head clamp from a used Wen Mac glow head. I subsequently tested the Merlin plug along with the older glow heads. This video documents the testing of these plugs in one of my Wen Mac MkXII engines. A Cox (black) 6x3 prop and 15% Sig Champion fuel were used in all tests.
A slide show illustrating the machining of a Wen Mac head clamp for a Merlin glow plug follows the running tests. Hope you like.

[@philipmetzner7243]

Fred, can you tell me what kind of needle valve you have in there? It looks like a replacement of some kind. I need some myself.

[@pampa9m]

philip metzner Phillip; the needle valve came with that engine. However, you can make your own needles with 0-80 brass screws. Just taper one end in a lathe or drill, and solder a flat piece of brass on the other end. Use a small pen style spring to give tension.

[@philipmetzner7243]

Fred, It looks like you have an intake extension on your test engine. Can you tell me about it? I have been thinking of trying that myself.

[@pampa9m]

Philip,
I just did this to keep the intake out of the exhaust. The original intake is quite large so I just inserted a section of aluminum tubing (K&S) into the intake (I think it dropped in press fit) with a bit of JB weld to hold it in place. Obviously clean the oil off first. Fred