Author Topic: Silver Angel won't start  (Read 2646 times)

Offline ponderosa_boy

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Silver Angel won't start
« on: May 04, 2016, 03:12:40 PM »
I've completed a Bob Shores' Silver Angel and cannot get it to start. Getting great spark to plug with Roy Sholl electronic ignition. Ignition timing set ~ 5 BTDC, exhaust opening 140 ATDC, closing 20 ATDC ( 240 crank degree duration ). Cut groove in top cylinder surface for .031 solid copper wire and left it protruding ~ .007. Made a fixture to pressure test head and it will hold 60 PSIG easily.

I ran the engine for sometime by lathe chuck for break in. It seems to turn freely. I am attempting to start it with a DeWalt battery drill.
I have no idea of where I am on carb mixture adjustment, except that I can richen it up and actually get liquid fuel out of muffler. Tried spraying starting fluid (ether) into carb while spinning - no luck. I have suspected a fuel fouled plug many times but each time I check, I get a good spark.

I feel as if I have a good lap fit between piston and cylinder wall, as I can put my thumb over end of cylinder and the bare piston will not fall out until I remove my thumb. Made cast iron rings per instructions. I made an adapter to install pressure gauge in spark plug hole and it seems to read about 20 PSIG when spinning over rapidly on speed #2 on battery drill.

Any help or suggestions will be most appreciated.

Offline Roger B

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Re: Silver Angel won't start
« Reply #1 on: May 04, 2016, 03:30:58 PM »
Are you getting any sign of firing, pops, smoke etc?

Are you sure that the spark is on the compression stroke and not on the exhaust stoke (I've done that  :facepalm: )

Have you tried advancing the ignition to 15 -20░ BTDC?

Do you have a spare spark plug? They can sometimes break down under pressure.

Can you post a couple of pictures of the engine? it's not one I am familiar with.
Best regards

Roger

Offline gbritnell

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Re: Silver Angel won't start
« Reply #2 on: May 04, 2016, 04:23:59 PM »
When you turn it over by hand does it feel like it has good compression, meaning is there resistance when it's on the compression stroke? I don't know what type of gauge setup you have for reading the cylinder pressure but if it's an accurate setup then 20 psi. is way too low.
Spark advance can be anywhere between 15-25 degrees to get the engine started. Once started it can be adjusted for optimal running.
I don't know what type of carb they use on that engine. All my carbs are of the air bleed type and to start my engines I leave the needle closed and then start turning the engine over with a cordless drill on high rpm (1500). While it's turning over I start opening the needle until I get some type of popping. (your throttle should be opened about 1/4 of the way).
gbritnell
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Offline ponderosa_boy

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Re: Silver Angel won't start
« Reply #3 on: May 06, 2016, 03:34:34 PM »
Here's 2 pics of my Silver Angel on the startup (Ha) stand:

Thanks to those that responded to my post. I'll attempt to answer your questions.

1st response:

No sign of pops or firing.

The ignition is triggered by a magnet in the flywheel and a Hall effect pickup; therefore it fires every crankshaft revolution, including a 'wasted' spark at top of exhaust stroke.

I will have to modify my ignition pickup to get this range of advance ( my bad ) but this will be one of my first priorities.

Will try another spark plug or two - I have 3-4 new ones.

2nd response:

I can feel some compression resistance, but the heavy flywheel dulls some feel. You can however feel some sucking by putting finger over carb and aso a small amount of pressure thru muffler. When spinning with drill, I can see the atmospheric intake valve cycling up and down.

Spark advance - see above. Modifying pickup.

Fuel mixture - there is no throttle in the simple 'carburetor'; engine speed governed by flyball that raises exhaust valve.

Agree that 20 PSIG is low; the rings are none too tight and I don't know of anything else that could be a contributor to compression problem.

Offline Jasonb

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Re: Silver Angel won't start
« Reply #4 on: May 06, 2016, 04:06:39 PM »
You may want to raise your tank a bit so the fuel level in the tank is just below needle height, as George says a lot of these engines need very little needle opening, often less than 1/4 of a turn.

Make sure your drill is not spinning things too fast and engaging the governor, I usually override the governor until things are running.

Not sure which direction this engine turns but make sure you have it going teh right way with the drill.

Move your ground wire up to as near to the plug as possible, maybe one of the exhaust studs would be east to fix the wire to.
« Last Edit: May 06, 2016, 04:11:05 PM by Jasonb »

Offline Admiral_dk

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Re: Silver Angel won't start
« Reply #5 on: May 06, 2016, 08:57:40 PM »
I don know this engine - though I've seen one built earlier - but from the pictures it seems to have a certain size, so I would expect quite a bit higher compression pressure. A lot of members have used O-rings as piston rings with great success, so maybe this is a way to get the first pops / run .... If this isn't enough to raise the pressure quite a bit - I would check the compression ratio / control measure it, since it appears to have well sealed valves.

Place the piston at TDC and fill some heavy oil through the sparkplug hole using something with a fine scale - this could be a syringe like or a measuring cylinder .

Now calculate the ratio - If the ratio is below some 4:1 you will have a hard time to get it to run.

Best wishes

Per

Offline Zephyrin

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Re: Silver Angel won't start
« Reply #6 on: May 06, 2016, 10:37:52 PM »
The compression 20 psi is much too low, clearly. as you dont suspect piston rings, then check the valve-valve seat sealing.
This can be done easily with the cylinder head alone, with the valve without  springs.
With a silicon tube inserted in the intake or exhaust port, you suck with a syringe, and by releasing the plunger of the syringe you should feel the vacuum. Or simply you suck with the mouth, the depression must keep your tongue tip in the tube for about 15 seconds. then the valve are not leaking.


Offline gbritnell

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Re: Silver Angel won't start
« Reply #7 on: May 07, 2016, 03:12:30 AM »
One of the hardest things to get right with I.C. engine is the valve seal. So many things have been written about it that I'm not going to cover it here but as Zephyrin stated you can just suck on it with your mouth and if there's the slightest leak you won't be able to hold any vacuum.
The basics of any I.C. engine are fuel, compression and spark. The spark and fuel are usually the easy parts the compression not so.
gbritnell
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Offline Admiral_dk

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Re: Silver Angel won't start
« Reply #8 on: May 07, 2016, 05:51:06 PM »
If the valves are leaking, I will have to agree with Zephyrin and George, - forget my advice - If the valves are not leaking, try the advice above to check if you have a geometrical error.