Yet Another Webster Begins

[werowance]

on my carb, no adjustment needed and only open abut 1/4 of the way for starting was its sweet spot for me.. i know everyones may need a little different changes though. the main mistake i was making was trying to start it backwards. i doubt you are but wanted to point it out just incase.

 

[CFLBob]

Good point, and thanks. I'm rotating the flywheel counterclockwise when viewed from the side with the points, like this.


I'm using a battery powered drill and I find that it sounds more like it's trying to start if I run it fast. I don't know how many RPMs either one is with my drill, but it has a switch that moves a gear so that it's either slower with more torque or faster with less.

This morning I woke up with a voice in my head saying, "double check your *&&$ing timing!"

 

[minh-thanh]

Hi CFLBob !
Make sure the atmospheric valve is moved "free ".
Put some oil w40 in the valve guide
With me, the atmospheric valve spring is only job : keeping the valve at the closed position with 1 force : very little force

 

[awake]

Bob, some thoughts & comments from my experience starting my Webster:

1) The obvious: do you have good compression? Does the intake valve "burp" when you turn it through the intake portion of the cycle?

2) Timing is a good thought - both exhaust and ignition. When I first attempted to start my Webster, I had no luck. I tried moving the exhaust cam by one gear tooth, and it started right up.

3) I have never succeeded in starting my Webster on the slow speed of the drill - which seems very odd since I can hand start it so long as the mixture is right. (It does take several attempts to hand start it, unless it is warmed up and the settings are dialed in - then it starts with a single spin.) But back to the drill - for some reason, when starting with the drill, it only works on high speed.

4) I'm not sure which screw you were talking about having 1 full turn, but if that is the mixture needle, it may be way too rich. That said, the nice thing about starting with a drill is that you can keep spinning it while adjusting the needle until it begins to catch. You can also use your finger to block the air intake on the carb to choke it - especially after mine has sat for a week or more, this helps to get it going.

5) You might try straight Coleman gas, without the WD40, at least until you get it running. I find that my Webster is harder to start and does not run as smoothly when I run mixed gas + WD40 - even what seems like a tiny amount of WD40. (I do run the occasional tank of mixed through just to be sure everything gets a bit of lube - maybe every 6th tank or so.)

6) What size throat is the Traxxas carburetor? If it is too big, it will be very hard to start. As I recall, the throat on my carb is .140", and that may be a big on the large size.

 

[werowance]

Bob, are you getting pops, burnt oily residue coming from the cylinder etc? I will say with my traxxas carb set at 1/4 throttle it does take a good 20 seconds of spinning it over before I can remove the drill off of it (I'm using the rubber disk on the fly wheel). I do get some noise from it but it wont take off on its on until about 20 seconds. alsoi use regular 5w30 oil on the cylinder oiler and on top of the valves etc. the 30 w oil will push out black crud when its doing some firing, slings it all down the base plate.

on the intake valve spring, mine was way to strong at first as well. if I remember right I finally ended up using the spring off a set of brushes from an old broken angle grinder. it was the right size and weak. just enough to keep the valve closed. but in your description the valve just barely moves. so does mine even when running.

 

[CFLBob]

Bob, are you getting pops, burnt oily residue coming from the cylinder etc? I will say with my traxxas carb set at 1/4 throttle it does take a good 20 seconds of spinning it over before I can remove the drill off of it (I'm using the rubber disk on the fly wheel). I do get some noise from it but it wont take off on its on until about 20 seconds. alsoi use regular 5w30 oil on the cylinder oiler and on top of the valves etc. the 30 w oil will push out black crud when its doing some firing, slings it all down the base plate.

on the intake valve spring, mine was way to strong at first as well. if I remember right I finally ended up using the spring off a set of brushes from an old broken angle grinder. it was the right size and weak. just enough to keep the valve closed. but in your description the valve just barely moves. so does mine even when running.

I'm getting oil spraying everywhere: baseplate, around the front of the cylinder, top of the head, sprayed across the work bench, on my pants, me, everything. I'm just not sure about being burnt. I get oil residue in the exhaust pipe.

A strange thing I'm seeing is what looks like the fuel oozing between the three segments of the valve stack. It's visible in the test video where you can see the fuel bubbling under the right hand screw at around the 50 second mark (it's not a specific time). Maybe my brown paper bag gaskets suck and I should use some of the gasket material I had to buy to make the head gasket.



The spark plug fired when lying next to the cylinder, before I started all this, so I appear to have spark and fuel. In the video, you can hear a puffing or snorting sound as I move the flywheel by hand.

What am I missing?

Before I tried again today, I used the instructions from Traxxas to reset the screws I messed with. It's pretty straightforward. I also double checked the ignition timing. It might be within a few degrees of TDC, and Joe Webster says "about 15 degrees before TDC." It's close to that.

BTW, I took that rubber disk trick when you mentioned it and am using one here. You'll see it.

 

[Brian Rupnow]

Your gaskets are leaking on the intake stack, and the engine isn't firing at all. You should have a transparent fuel line so that you can actually see the fuel being sucked up by the carburetor, and your intake valve spring is probably too strong.

 

[stevehuckss396]

I agree with Rupnow. I don't see the intake valve opening. Don't see any movement at all.

 

[coulsea]

My battery drill will not start a new engine, just not fast enough (1200 rpm should work), if you have leaks in the valve block, valves, rings and head it all adds up to not enough compression to fire. intake valves don't move much, a finger over the intake will tell you if it is sucking at all, same with exhaust blowing. a few drops of oil down the bore may help (not WD40). everything the others said is correct as well.

 

[CFLBob]

Your gaskets are leaking on the intake stack, and the engine isn't firing at all. You should have a transparent fuel line so that you can actually see the fuel being sucked up by the carburetor, and your intake valve spring is probably too strong.

#1 is easy; I have plenty left over.
#2 is puzzling. As I said, the spark plug was firing out of the cylinder head, just lying on the base of the engine. You can see the LED flashing at the far end of the S/S CDI box, which was flashing every time the points closed and triggered the spark. All I can do is pull the plug again and see what it looks like outside the engine.
#3 that fuel line is transparent and I can see into it. It appears full of fuel. Seems it would have to be full.
#4 the valve spring is made with .015 wire instead of the .013 called out because I didn't have any .013.

My battery drill will not start a new engine, just not fast enough (1200 rpm should work),

My battery drill has two modes which give lower and higher RPM. I'm using the high speed one. The manual says 1,600 RPM with no load, which doesn't say much. I also have two AC powered hand drills. I can look into which is faster.

Question: Webster says (page 20), " Rotating the flywheel counter-clockwise (viewed from the flywheel side) should produce a "snorting" sound through the carburetor as the intake valve lifts. Since the flywheel is very visible from any side, I want to know if I'm correct in rotating it counterclockwise in the view in the video. I would call that the ignition points side. (I would call the opposite side the cylinder and combustion chamber side).

I thought that sound I got out of the engine on every rotation of the flywheel (in the first 20 seconds of the video) was the snort I should be listening for. It's very audible although I had to turn up the volume. If that's indicating the intake valve is working, I'll work on other things first.

 

[Brian Rupnow]

.015 diameter spring wire should be fine for an air actuated intake valve. Turn the engine by hand, in the direction you think it should be turning, with the sparkplug laying out on the block. You should see an actual spark at the plug just before the piston reaches top dead center. The cam operated exhaust valve should begin to open about 3/4 of the way thru the power stroke (piston going towards bottom dead center). Exhaust valve should be fully closed at or just before the piston reaches top dead center on the exhaust stroke. If you want to check for compression leaks, squirt a little undiluted dish-washing detergent around the places you think may be leaking and turn the engine over with your drill while watching for bubbles. (with sparkplug in). Check for leaks around the sparkplug.

 

[Longboy]

Check your valve closure for leaks using a compressor blow off nozzle (at single digit PSI) thru the spark plug hole. Your spark timing should be at TDC. One turn open on the Traxxas carb. Throttle open near a quarter or less. Your ex. valve should be closed at TDC. If you are getting fuel mix dripping outta the cylinder on priming, the carb is feeding the combustion chamber. If not, the in. valve is not moving. I see the fuel weepage on the valve block. If there's fuel there can be air leaking too. I have used painters tape and Scotch tape for a gasket. Make sure the batteries are charged up. They get down below 1 point zero something, its all over at the spark plug. You can't start a model engine with a cordless drill on the slow setting. What really bothers me is: I'm looking at your video and going frame to frame to where the ex. valve closed. Your con rod looks somewhere near the 12 O'clock high position then. That is way beyond where it needs to be closed and kinda confirmed a similar rod angle with the ex. valve opening. My best bet then is intake valve not opening because the exhaust valve is open way after TDC for the intake stroke.

 

[coulsea]

Looking back at your video I notice that you don't touch the carby. I have tried those carbs and found that they don't function like they should because they are designed for a different fuel and a different rev range. Not saying it's no good but it may only work through part of the throttle range, so start turning it over with the throttle closed and slowly open open it up. if that doesn't work I would try 3/4 throttle with the mixture screw in and then slowly turn it out while cranking it over. You can use the drill chucked directly onto the crank to make it easier to use one hand on the carb, just until you start getting some bangs. Each engine is unique and you have to learn what it needs, the old british single motor bikes had their own character and people would say "yes you can ride it if you can start it".

 

[Steamchick]

Brian, I am Glad someone with experience says the intake valve spring should be OK... I thought the wire, although only 2 thou thicker, would be more than twice as stiff as the planned size, needing twice as many turns to make it as soft as designed. (Stiffness goes up as the cube of diameter!). But I haven't made a working infernal combustion engine myself.
Bob, I don't know your ignition box of tricks. My experience is only with points and coil systems that fir the coil when contacts BREAK. The contact closed time charges the system (maybe why the LED illuminates?), the break triggers the coil to make the spark. Therefore a system timed on contacts "making" is new to me. Just check your instructions? - Can you see the piston position when the spark occurs? (PLUG outside engine, looking through the plug hole? Or by the crank position, or looking up the cylinder at the bottom of the piston?).
Personally, I suspect a lack of air, either because the valve spring is too strong so too little intake, or carburation is too rich. But wrong ignition timing and it will never run either.
But good comments from everyone else (with more expertise), so maybe I am wrong?
Good fun making it run!
K2
K2
K2

 

[scottyp]

Plenty of good info for you to digest. Let me add to that. This engine is pretty forgiving, but we need to have things at least close to the correct timings. We need Suck-Squeeze-Bang-Blow, fuel and spark do help.

This is my approach and other's mileage may vary but here goes.

Let's start with Squeeze. As you turn the flywheel by hand in the running direction (spark plug installed), on the compression stroke you should definitely feel the compression of the air and if there are little to no leaks, the piston should "spring" back against you if you let go of the flywheel. If there are leaks, they will show up here. As Brian mentioned, a little soapy water on the valve block (gasket issues), also listen for air leaking out the carb and/or out the exhaust (valves not sealing). As you compress the air, tap the intake valve and you should get a good little pop out through the carb. Since you will most likely have the valve block off at some point, check your compression by plugging the intake port on the engine frame with your finger, you should have good piston spring back. In either case, a SMALL, SLOW leak MAY not impede starting, but let's go for a negligible leak. Make sure you are adding a bit of oil (not the WD40) to the piston to help lube and seal things.

OK, Bang. Once you have the above compression good, turn the flywheel to TDC on compression and release the air by hitting the intake valve. Since we don't have spark going right now, no bang here, but as you now continue turning the flywheel the piston should draw in and the intake valve should give you that little burp people are talking about.

OK, Blow. Holding you finger over the exhaust pipe and continue turning the flywheel. As the piston goes back into the cylinder you should feel the air being pushed out by the piston and you should be able to feel that resistance in the flywheel. Watch and listen for leaks...

Now, Suck. As you continue turning the flywheel, you should get another intake burp (this time, the real intake stroke). And if you hold your finger over the carb intake, you should feel that suction.

Once you like things above, make sure you have spark at the correct time as Brian mentioned.

Add fuel, close the mixture needle, and make sure the throttle barrel is wide open. Then choke the carb with your finger and turn the flywheel by hand on the intake stoke and no fuel should be getting sucked up the fuel line. Repeat this and open the needle 1/4 turn at a time until you see fuel getting drawn up into the carb. Now add a couple of extra intake stroke "primes" to make sure there is fuel in the cylinder and we should be ready to add spark.

Set the throttle to ~ 1/4 open, connect your ignition and give it a little spin and it should fire. It may not keep running and you will probably have to adjust the mixture and throttle setting to keep it running.

Not directly related to this specific thread but, my opinion, experience and technique is that IF an engine is PRIMED properly before trying to run it, all it should take to get it to at least fire is a flip or two past compression. If I find myself cranking and cranking, something is wrong. Your mileage may vary...

 

[CFLBob]

I can't thank you all enough, and if I had to single out one reply it's @scottyp's detailed step by step. It will take some time to go through, but I'll update things if anything noteworthy shows up, one big thing, I'll be back sooner, but will update you all.

 

[wburnett2922]

your engine is way to tight to run engine must be free also there can be no leaks as not only will compression not be there also will change mixture. take out spark plug fill cly with oil put plug back in turn engine by hand up against compression see where leaks are fix them a little extra oil in cly at start up will improve compression any questions contact me

 

[CFLBob]

your engine is way to tight to run engine must be free also there can be no leaks as not only will compression not be there also will change mixture. take out spark plug fill cly with oil put plug back in turn engine by hand up against compression see where leaks are fix them a little extra oil in cly at start up will improve compression any questions contact me

Interesting. I thought the engine was too loose. When I pull the piston back in the cylinder, I don't get any resistance like @scottyp said to check for. With the carb fuel line disconnected, I do get a healthy puff out of the open end of the carburetor when I spin the flywheel by hand. I take that as a good sign.

I stepped back to take a "first things first" and replaced the gaskets in the valve block. While the valve block was off, I fixed something that had been an issue. The cylinder head is held to the base with three screws, one from the under side, two on the side frame. Those screws would get loose under vibration, so I tightened them and used some of that easy to break blue LocTite. I also pulled the spark plug and verified it was still sparking.

I'm letting that cure overnight before I shake it up more.

@Steamchick and anyone else with the question about the way the points are firing - the instructions that come with the CNCengines ignition say the points will work either normally open (Kettering System) or normally closed. Watching the points and the red LED, I think the points are actually firing when the points reopen, not when they close. The amount of time they're closed is very small.

What really bothers me is: I'm looking at your video and going frame to frame to where the ex. valve closed. Your con rod looks somewhere near the 12 O'clock high position then.

On the rocker arm, there's a 4-40 screw that pushes on the exhaust valve. That had also gotten loose and made it worse. I just put that back in position with a drop of blue LocTite on it. Back when I was first assembling the engine, I made a little drawing to help me line things up like on p.21 of the plans, since I'm using a different crankshaft throw than the straight one Webster used. He says the angle between the piston conn rod center and the center axis of the flywheel should be 15 degrees. This is how my sector of a circle should look:

I rechecked that with my angle gauge and instead of being 8 degrees to the horizontal, it was 9. That means in stead of 15 degrees joining those two axes, it's 14.

 

[minh-thanh]

CFLBob

In your video I seem to see the engine looks like it has no compression or very little compression ,Or am I wrong !?
my engine :

 

[coulsea]

I do get a healthy puff out of the open end of the carburetor when I spin the flywheel by hand. I take that as a good sign

The carb should suck not blow.
valve timing being out by 1 degree is insignificant. as long as the exhaust valve closes at or just before TDC in order to get the full intake stroke.