startin' on a Webster

[dgjessing]

My engine also seems to be really sensitive to the level of fuel in the fuel tank.

The thing is driving me nuts!

Chuck

I'm developing a theory related to this... My tank has an air inlet tube that runs straight up and down, and I can move it closer or further away from the fuel level by sliding it in and out of the valve block. I've been screwing around with this adjustment some today.

On the intake stroke air is effectively blown down at the surface of the fuel, agitating it. The closer to the surface of the "pond", the more agitation. Also, the faster it runs, the more agitation because the air is coming in faster. The agitation increases the exposed surface of fuel, effectively making the mixture richer. I think that the unsteady idle I'm experiencing is caused by the mixture varying like this - it speed up, gets too rich, then slows down and leans out, making it run faster, and around and around we go.

I'm going to experiment with some sort of diffuser on the end of the air inlet tube which makes the air blow out sideways instead of directly down. Maybe that will calm things down (?).

 

[dgjessing]

Hey - it works! I stuffed a wad of coarse steel wool into the tank and now the thing can run at a constant speed, and for much longer. ;D

 

[vcutajar]

That's good news Dave.

Vince

 

[cfellows]

Hey - it works! I stuffed a wad of coarse steel wool into the tank and now the thing can run at a constant speed, and for much longer. ;D

Good idea, I'll have to try that. Here's a picture of an inlet tube I made to diffuse and spread out the air flow. That also seems to help.

Hmmm, wonder if a wad of swarf would work instead of steel wool ???

Chuck

 

[dgjessing]

The steel wool thing must have been a fluke - it's no help today

I'm about ready to give up and buy a proper model airplane engine carburetor (although I'll no doubt try your inlet tube, Chuck while I'm waiting for it to arrive).

I guess this is why you don't see vapor carbs in use on "real" small engines :

 

[Paulsv]

I'm wondering if these might be possibilities to consider for the Webster:

Jerry Howell's 2-Jet throtttle carb:

http://www.model-engine-plans.com/engineplans/combustion/howell2jet.htm?30,10

Or his propane system:

http://www.model-engine-plans.com/engineplans/bookshelf/demandvalve.htm

 

[Catminer]

Only one way to find out

Peter

 

[cfellows]

I'm wondering if these might be possibilities to consider for the Webster:

Jerry Howell's 2-Jet throtttle carb:

http://www.model-engine-plans.com/engineplans/combustion/howell2jet.htm?30,10

Or his propane system:

http://www.model-engine-plans.com/engineplans/bookshelf/demandvalve.htm

I have a set of the Jerry Howell 2-jet carburetor plans. They are kind of complicated and hard to figure out. I also have a set of carburetor plans from Bob Shores which is simpler and easier to understand. I might give that one a shot.

http://www.bobshores.com/bullethercules.html

Chuck

 

[dgjessing]

Well this afternoon me and the vapor carb and the Webster are getting along pretty well together. I seem to have hit upon a set of optimal settings for the two adjustment screws and the fuel level (the later is a big deal as you say, Chuck.). Sigh...

I've started it up several times over the past hour and it idles pretty steady at about 180 to 200 rpm every time. If it behaves the same way tomorrow and next week I'll be pretty happy

 

[fcheslop]

Good luck with the carbs watching closely as I have a Little Angel and some days it will run with a simple push on the flywheel and other days just wont, it will pop and bang but not go and it seems even worse in the winter.
It just doesn't live up to its name
Nice job on the Webster :bow: :bow: :bow: :bow:
best wishes Frazer

 

[dgjessing]

It's been running pretty darn reliably lately; I've been turning it off with the switch rather than just having it die all day today ;D

Made the little slashed-end exhaust pipe for it per the plans, which I swear is making it run better :

 

[dgjessing]

I guess I've taken a three year break . (Been playing with model airplanes ).

Anyway, contrary to what I said in the last post, the Webster never did work reliably with the vapor carburetor. It's mainly been collecting dust... But a few months ago I fitted a model airplane engine carb to it, and this afternoon I made a bracket to hold a fuel tank, and this evening I've got it running!

Pictures soon

 

[dgjessing]

Well not so fast.... It is indeed running much more reliably, but I'm having an issue with the piston tightening up in the bore as it gets hot. I'm thinking the viton o-ring piston ring is probably at fault. After a cold start, perhaps 4 minutes into running nice and steady it starts to squeak a bit, then soon abruptly stops. The piston is obviously tighter right afterwards. Let it cool off and repeat. I'll take it apart and look into it soon.

I'm running it on fully synthetic, 10% nitro glow fuel. This because I've always got this stuff around for the model airplanes.

I have retarded the ignition timing a bit, from just before TDC to just after, which helps to smooth out the running.

I seem to have the needle valve setting and starting procedure worked out for pretty good reliability.

I need to make up a friction holding gizmo for the throttle arm.

 

[dgjessing]

Hey long time no see! This time the delay has been motorcycles taking up all my time.

Still into that, but the other day I got the Webster down off the shelf and cleaned it up. The battery was of course dead (5 years...) so instead I put some leads on it so the ignition runs off a 12v power supply. Big fat blue spark now . After no luck with the model airplane carb I went back to the original vapor carb. Still no luck, but I noticed it would run briefly if I pushed down the intake valve while cranking it. Just now, I rooted through my spring collection and found a lighter one for the intake valve, and that's done the trick! I believe it's running better than ever before - starts right up and runs pretty steady until I turn off the ignition.

The big end rod bearing is really sloppy - need to fix that.