Webster Engine

[65arboc]

Just finished the Webster and it won't run on it's own but first question I need answered is which way the flywheel rotates looking at the Points side, cw or ccw ? It turns free and has decent compression. My small timing gear has double set screws so I can adjust the timing.. I have had it firing very well running it with a drill in the cw direction but I think it should run ccw.

Thanks for any help.

Jim in Pa

 

[65arboc]

No one wants to help? Simple question.

 

[GailInNM]

I don't have a Webster set of drawings convenient at the moment so this will be a general answer.
If you rotate the flywheel in the direction that you want the engine to run, the exhaust valve should start to open about 20 to 30° of crankshaft rotation before you reach bottom dead center. Continuing to rotate the flywheel the exhaust valve should be fully closed shortly after reaching the top dead center.
Gail in NM

 

[GailInNM]

I pulled up my set of Webster drawings to double check my memory.

Everything is symmetrical on the Webster so it will run in either direction equally well. Your preference as to the direction of rotation. As the Webster is a low-speed engine cam timing will not be extremely critical. I checked the Webster cam drawing and the flanks are 125° of crankshaft rotation apart. For starters, I would set the cam for the exhaust opening starting at 25° before bottom dead center and an fully closed at 10° after top dead center. In practice, you won't have quite the full 125° of operation because of the necessary few degrees of tappet clearance. Just split the difference and you will be fine.

The ignition cam will also have to be set depending on your rotation preference. For starters I would just set the cam so the points start to open about 5° before top dead center on the compression stroke. Really, on a low-speed engine all you really need to do is make sure that you are slightly before top dead center and not after top dead center.

These are not optimized settings but are settings that should make the engine run okay. After you have the the engine running satisfactorily you can tweak these settings but I think you will find that you can vary quite a bit from them without making a significant difference in performance. Low-speed engines with atmospheric valves are not very demanding of the settings.

Gail in NM

 

[65arboc]

Gail,

That is a great way to answer my question, very clear. I suspected it would run either direction but wasn't sure. Las night I got i firing ccw on every 4th stroke like it should but only with the drill attached. It still will not keep running on it's own. Using Coleman fuel btw. Thank you very much for your reply.

Jim

 

[GailInNM]

Jim,
it sounds like you're getting close. At this point you can be fairly sure that both your valve and ignition timing are set close enough that the engine should run.

The most common problem, in my opinion, that beginners make with atmospheric intake valves is that the spring tension on the intake valve is too high. It is quite critical. When the tension is too high the intake valve does not open soon enough and the cylinder does not get a full charge of fuel air mixture. When this happens the power stroke is too weak to get the engine to run continuously.

I looked at the Webster drawings again and did a rough calculation of where the spring should be set. With the intake valve held in closed position and the spring retaining pin removed the top of the valve keeper should be about the top of the hole for the spring retaining pin in the valve stem or no more than 0.010 inch above it. With it set correctly you should be able to set the piston at top dead center where the exhaust valve is just closing and rotate the flywheel by hand fairly rapidly and if you're in a quiet environment hear the intake valve opening on the intake stroke. Since I'm an old man I can say this, but it should sound like an old man passing gas as the intake valve will vibrate. The valve will only move a few thousandths of an inch so only rarely will you be able to see it move.

If this doesn't cure the problem, then you probably have some compression leakage in either the piston cylinder fit or the valve seats. It's fairly easy to determine which and I will be glad to walk you through it if necessary.

Gail in NM

 

[65arboc]

Hi Gail,


I really appreciate all the advice you have taken the time to help me. I played around with it last nite until I was ready to throw it in the trash. It wouldn't run. At the last moment I closed the air valve for the vapor carb and saw fuel pop out the filler tube. I think my intake valve is leaking by even tho I have decent compression. Today I am going to lap the valves again and also check the spring tension of the intake valve. I do see the intake valve working up and down as I try to start it. I will let you know if I get it started today. Thanks again for your help.

Jim

 

[Swifty]

Jim, with a new engine, a lot of starting problems are due too leaking valves. Preserving with the drill and getting the engine to pop will often help with bedding in the valves. There are some members that actually hook up an electric motor to turn the engine for a while to help with bedding in, I have never done this, I just keep using the drill for a while.

Paul.

 

[65arboc]

I lapped the intake valve and seat like a mirror today and it still wont run. Picked up an O-ring for the piston today. Maybe more compression is needed. I really didn't want to ring it but I'm at wits end of why it won't run Everything seems right. Maybe I should stick to steam engines, the last 2 both run nice.

 

[65arboc]

Paul,

Thanks, I've lost track of how many times I've charged my drill!

 

[canadianhorsepower]

I lapped the intake valve and seat like a mirror today and it still wont run.

The mirror look is not a gauge to valve seating.:wall:
Take a pencil LEAD and mark your valve seat and and valve guide
assemble them and slowly rotate by hand " 2/3 turn is plenty.
then take your valve out and you should be able to see a nice
small CONTINUOUS LINE in the middle of your valve seat AND
valve face. If not Keep lapping.:fan:
Or use a vacuum pump "hand one" attache it to your valve cage
put your valve in the hole and apply vacuum It SHOULD NOT LEAK.
good luck

 

[Mechanicboy]

The lapped valve and valve seat surface will be dull, no blank. Under running-in the engine will improve fit between valve and valve seat. Rotate the valve in both ways with lapping paste applied and check the valve is in full contact with valve seat ---> use vacuum + oil to spot there is no oil sucket into between valve/valve seat.

 

[65arboc]

The mirror look is not a gauge to valve seating.:wall:
Take a pencil LEAD and mark your valve seat and and valve guide
assemble them and slowly rotate by hand " 2/3 turn is plenty.
then take your valve out and you should be able to see a nice
small CONTINUOUS LINE in the middle of your valve seat AND
valve face.



I have lapped valves before and know the procedure well but thanks. I have a nice continuous line on both. It's something else why it won't run. I am getting combustion because the cylinder and head get real hot after running the battery down on the drill and I can smell the burned coleman fuel. It turns free and the piston will bounce back on the compression cycle. I have a head gasket installed and also a gasket in the valve body itself and one where the valve body attaches to the head. I have already replaced 1 main bearing on the ignition side because it was bouncing around. I'm wearing out my 6 year old drill battery and me:wall:

 

[chrispare]

Put regular gas in it it'll run mint I bet.
I have a hit n miss that just will not run on Coleman fuel even if I start it with regular gas and and switch.

 

[10K Pete]

I seem to recall that in the process of getting a Tiny IC (Putt Putt Man?)
going that regular gas was needed instead of white gas.....

Pete

 

[canadianhorsepower]

[QUOTE I am getting combustion because the cylinder and head get real hot after running the battery down on the drill and I can smell the burned coleman fuel.:[/QUOTE]

if that's the case I would bump the timing quite a bit.
somehow if you have to much advance it will kick, so you know
you have to much. many people believe that all same model engine
need the same timing and that's wrong.
depending of your scavenging you might nrrd more or less advance
good luck

 

[Brian Rupnow]

I feel your pain. When you have done everything you can and the engine still won't run, it makes you kinda crazy. Been there. done that. Everyone is giving you good advice. You do need a ring on that piston. My first choice is a 1/16" cross section Viton o-ring. The groove for it in the piston should be .057" to .059" deep and .093" wide (the width of a standard parting-off tool), about 3/16" down from the top of the piston. Lap the valve with 600 grit lapping past. The contact area of the valve and seat should be very narrow----.015" to .020" is all it needs. More contact area is NOT better. The valve shouldn't be too tight in it's guide. This will let the valve move around a very very small amount to settle itself concentric with the valve seat. All mating surfaces should have a gasket. I have never been able to machine mating surfaces to such a high finish that they will seal without a gasket. The spring on the long rocker arm seldom gives the action that you hope it would. I recommend fitting a small compression spring under the end of the rocker arm closest to the cam to make certain that it really does follow the cam. If you are turning the engine clockwise, then the exhaust valve should just be starting (as in just being touched by) the rocker arm at about 1/8" before bottom dead center on the power stroke. Ignition timing, as a starting point, should be set to give a spark at exactly top dead center. You can always advance or retard it a little after the engine is actually for a while. The gas tank, at it's fullest level, should be slightly below the air-horn of the carburetor, not above it. If none of this helps, send an email to [email protected] with your phone number and I will call and try to talk you through it.---Brian Rupnow

 

[65arboc]

I'd like to thank everyone for their help, especially Brian. I am going to go over everything tonight step by step and see what may be wrong. I think the spring under the exhaust valve may be the answer as the lever may be bouncing off the cam at times. That could be the reason why it fires sometimes and not sometimes. I'm also putting a ring on the piston. Maybe this thing won't end up in the trash after all

 

[Brian Rupnow]

So---We are anxiously waiting to hear your results-------Brian

 

[65arboc]

Sorry,

Some other things got in the way for now.