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Delco and other Low Voltage DC Light Plants Antique Generators, Light Plants, Typically 24, 32 or 48 volt although some are 110 volt. DC Lamps, Motors and appliances.

Delco and other Low Voltage DC Light Plants

Irritating miss in my 850.....


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  #1  
Old 06-23-2017, 06:21:03 PM
George Andreasen George Andreasen is offline
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Default Irritating miss in my 850.....

My Delco Light 850 has new rings, valves, valve guides, cylinder honed, crankcase all cleaned out, rewired using a modern coil and a shutoff switch to kill the ignition. All electrics were overhauled and double checked per the factory information. I plumbed the fuel line with a loop, the idea being to keep a small supply in the line for starting.

In short, I've done everything I can think of to make a good, usable generator. Here's the problem: It starts with difficulty, needing a good bit of cranking first as if it's not getting fuel right away. Once it begins to fire, run and warm up a bit, it putts along (although occasionally it overspeeds then settles down). There is also a miss every few seconds.

Note: the batteries are fully charged during this test.

I thought the problem might be in the fuel system so I removed the felt from the priming hole on top of the mixer and plugged it with a bit of clay, the intent being to keep the fuel/air mixture more uniform. This helped a bit, but it still has the miss and the air control lever seems pretty "ticklish" for a good run. It's possible that my loop in the fuel line might have too much resistance to draw the fuel too.

There's an old expression that says "99% of all carburetor troubles are electrical". I'm beginning to think my points might be at fault, so that's the next thing I'll check. Does anyone else have any ideas?

Thanks guys!
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Old 06-23-2017, 08:36:45 PM
turbo turbo is offline
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Default Re: Irritating miss in my 850.....

Buy and inline spark checker or use a timing light and watch the pulses as it runs. If it is spark related you will clearly see it with the pulses. Also I have had spark plugs cause this problem and you won't see it with this method so keep that in mind too.
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Old 06-23-2017, 10:30:04 PM
George Andreasen George Andreasen is offline
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Default Re: Irritating miss in my 850.....

Thanks Turbo...........I just finished removing the loop from the fuel line and made it straight like the factory. It starts a wee bit quicker now, but that blasted miss is still there so it looks like I'll be following your suggestion next!
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Old 06-24-2017, 12:42:42 PM
Andrew Mackey Andrew Mackey is offline
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Default Re: Irritating miss in my 850.....

Slip a white business or index card between the point faces. Draw out a bit, but NOT clear out. Open points remove and look at the card. It should be clean white. Any residue, and the points are dirty. Repeat until the card comes out clean. The reason for not drawing clean out is that the paper can tear, leaving a bit on the points faces. Have you replaced the condenser? If so, might be defective. Have a look at the plug. Color - grey or dry black - too rich. Wet oily black - incomplete combustion or rings not seated (oil is bypassing). proper weight oil in engine? Insulater bone white or pale tan - possibly too lean a mixture. You can get a neon spark tester from a good auto supply, like NAPA for around 10 bucks. A cheap way to see if you have consistant spark. Plug gap right -should be about .035 if you are using a modern coil. One last thing - and it is not common - remove the coil lead from the points,and check resistance with the points closed, with an OHM meter.. Sometimes the point contacters, where they meet the mounts (fixed and movable) can corrode between the surfaces, If that happens, the resisyance will affect spark. The points will have to be replaced. let us know what you find
Andrew
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Old 06-24-2017, 07:51:08 PM
George Andreasen George Andreasen is offline
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Default Re: Irritating miss in my 850.....

Update: I think I got it.

I checked the points first, both for gap and cleanliness, and they seem fine. The condenser is a modern .47 microfarad with a 650 volt rating by the way. As a further precaution I sprayed NAPA brake cleaner on the business card and pulled it through the points several times......no indication of dirt but they're definitely clean now.

I'm running a new Autolight 3076 spark plug and I pulled it out also. To my surprise it had a minor coating of black, fluffy carbon.....too rich! I cleaned it completely and checked the gap. Here's where things get interesting. For reasons unknown, the plug gap was around .025 or less. I opened it up to .035 and reinstalled it in the engine. I'm a little baffled as I installed this plug originally......did I forget to check the gap? Edit: I checked my Delco Light information and the plug is supposed to be set using "the thick part of the wrench/gauge" (supplied with generator) OR the "thickness of a dime". I just measured a dime at .020, so that's why I set it so narrow. I left the plug gapped at .035.

When running this engine before, there was never any indication of an over rich mixture.....no black smoke, etc.

I put a drop of oil on the valves and cranked it over, using full choke and then moving the air control back to about half way. The engine began firing and once it steadied down I moved the air control over "just a touch" to the lean side. The muffler goes through my shop wall to the outside, so I walked out and listened to the exhaust note....never missed a beat for the first time since it's rebuild. Were the points a little dirty? Spark plug gap too narrow? I suspect the plug gap was the culprit, but I'll run it a bit more in the upcoming days and pull the plug again to see what's what.

Thanks for all the tips, guys!

Last edited by George Andreasen; 06-24-2017 at 08:31:52 PM.
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