Large Model Association Forum

I'm not too familiar with 3W,
This ones quite early, came installed in a 74" Biplane that I bought in 2000
Its all languished in the loft ever since.....shame...
Prop hub is 45mm it has a CM-6 plug, screwed into a steel insert on the cylinder
The prop that was fitted is 20" approx 10 or 12 pitch
Any clues?
The engine is low hours, perhaps even still to run in
Plug cap doesn't look too good
& I suspect the carb may need at least a good clean, if not new diaphrams

Looks like an early 45 or 60cc motor, difficult to tell without some scale to the photo.
I am a bit concerned at your comment that the plug thread has a steel insert as I am not aware of any 3W motors that were built that way. I guess the original thread has been stripped at sometime and an insert fitted.

John

Hello John,
I wondered about the insert too, unfortunately the previous owner is no longer with us, Davey was a mechanical wizard
but the engine looks barely run in, the piston shows no marks, the honing marks are still very visible on the cylinder and the exhaust port shows very little blackening, you can still see clean metal.
Plus the Biplane wings had a single 1/2 x1/4 spruce main spar with lightening holes!! and it used shearing elastic for rigging wires.
I doubt it had many flights with banana shaped wings!! Probably survived the maiden flight then was put away
What I'm getting to is I don't see Davey modifying the engine without reason.
But then perhaps the bigger plug didn't fit under the cowl!!!!!

Perhaps the real test should be bolt it onto a test stand and see what it'll turn

Thank you for your deliberation, I've taken more shots this morning with measuring tape in shot hopefully this helps.

Looks like a 60, i will dig one of mine out and compare measurements, the insert looks like a repair, the counter bore looks non standard that it is sat in, whoever did it, knew what he was doing!

That would be good to see Alan

Well comparing piston size through the port, probably an imperfect practise, with my G62 the bore sizes are very similar.
can't really measure stroke as I'd need to dismantle cylinder, then split crankcase, don't really want to take it apart.
I note there is a 'blank' casting surface on the top of the cylinder for a vertical plug perhaps

I've sent pics to 3W Support, never know they may reply

Ta all for looking,

Leave it with me, bit busy today with work and a house move

Hi All,
I've just had a reply from 3 W

This is very old 3W35 maybe 25 years old

Mit freundlichen Grüßen
Peter Weinhold

So there we go!

Hi Dave,
3W are very good at replying to queries - have to say it must be old .If you haven't tried the ignition yet,I would be suprised if it still works.
Rexcyl make a unit that does work but needs a little fiddling with the pickup to get the timing right.I just fitted one to an old 40 3W ,which has the same shape of mount ,last year runs very well so worth the effort.

Pete

Hi Pete,
Mmh yes id heard that early 3w cdi can be fussy, I havent had the chance to run it yet, at the moment it never seems to stop raining in West Scotland
I also need to modify the throttle arm to allow control from the back of the engine
Good to know the Rexcel CDi works should the orig be shot, as I said earlier the engine has definately got low hours and 3W seem to have a reputation of longevity and reasonably powerful units.
So well worth persevering even though its only a 35, cheers lads

This a 3W 40cc, I had one for years. 19-10 or 20-10 prop.

I've got a 3W 40 and the measurements are not the same.