Sooty plugs/blue smoke

F

freebird

Well-known member
Gosh it's been a long time and my username still works haha. So my plugs were black and sooty and plug 3 was wet. I figure either rings bad or stuck so I poured seafoam into the cylinders and let set for 3 days. After that I added Triax engine flush to the crank, started and let run 15-20 minutes at medium speed. My compression values before/after 1=125/125, 2=125/125 3=75/110 4=90/110. I also tested spark with an inline tester. It shows spark but I suspect it may be weak. I am running Champion D21 plugs gapped at .025. I cleaned the points but did not set gap...here is my problem there. I can't get my fat fingers in there or see very well. I also cleaned the wire connectors going from the coil to distributer and voltage regulator. I'm thinking my next step is to buy a new 6v coil. If I'm to put new points/condenser in I'll have to pull the distributer. Cap and rotor and plug wires about 1 year old. I'll have to read up on that. Is it possible to mark where the rotor points and maybe draw a line on the block/distributor housing to get me close when I reassemble? I know this is a lot and I'm kinda rambling but it's been a long day. Thanks for input guys.
 
freebird said:
I've done searches but have not found what psi compression I should have. I did read 90+ is good though.
Click to expand...
Hi,
The Cub and LoBoy service manual says a Cub before serial number 192113, which was made in later 1955, should have 107 lbs of compression. That is probably for a new engine, some less is ok, they have said on here 90 lbs or more is ok.
The manual says after 192113, they should have 120 lbs.
When doing a compression test, have all 4 spark plugs out of the engine at the same time, and open the throttle fully, so the engine can get air for the test.

Piston rings commonly get stuck when the Cub is sitting.
They have said on here to use Seafoam in the engine oil to possibly help oil burning, and raise compression, if the rings need freeing.
One of the experts on here said to use it for 2 oil change periods.
The 1950 Cub owner's manual says to change the oil every 120 hours of use.

I would turn the engine to number 1 cylinder TDC before removing the distributor.
The rotor should be turned to the upper right then, looking at it from the rear of the cap forward.
The Cub service manual says set the timing with a timing light, with the engine running.
The TDC mark should be aligned with the pointer with the engine running at slow idle speed, about 500 RPM. :)
 
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Glen said:
Hi,
You didn't say the year of the Cub.
Click to expand...

It is a 1956.
Glen said:
The Cub and LoBoy service manual says a Cub before serial number 192113, which was made in later 1955, should have 107 lbs of compression. That is probably for a new engine, some less is ok, they have said on here 90 lbs or more is ok.
The manual says after 192113, they should have 120 lbs.
When doing a compression test, have all 4 spark plugs out of the engine at the same time, and open the throttle fully, so the engine can get air for the test.
Click to expand...
I did not do that I did one spark plug at a time and started the engine for each test. I'll have to re-test.
Glen said:
Piston rings commonly get stuck when the Cub is sitting.
They have said on here to use Seafoam in the engine oil to possibly help oil burning, and raise compression, if the rings need freeing.
One of the experts on here said to use it for 2 oil change periods.
The 1950 Cub owner's manual says to change the oil every 120 hours of use.
Click to expand...
I will introduce seafoam to the crankcase. I am sure I have not put 120 hrs on it between oil changes.
Glen said:
I would turn the engine to number 1 cylinder TDC before removing the distributor.
The rotor should be turned to the upper right then, looking at it from the rear of the cap forward.
The Cub service manual says set the timing with a timing light, with the engine running.
The TDC mark should be aligned with the pointer with the engine running at slow idle speed, about 500 RPM.
Click to expand...
Thank you for that info as I've ordered new points and condenser and plan on removing the distributor. Hope I can find a 6v timing light cheap OR will a 12v work and maybe replace the bulb?
Glen said:
:)
Click to expand...
 
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freebird said:
It is a 1956.
Click to expand...
Your info says the Cub is a 1952, and the LoBoy is a 1956.

freebird said:
I did not do that I did one spark plug at a time and started the engine for each test. I'll have to re-test.
Click to expand...
A compression test is done using the starter, charge the battery fully first if it's not fully charged.

The 1957 LoBoy operator's manual says change the oil every 150 hours of use.

freebird said:
Thank you for that info as I've ordered new points and condenser and plan on removing the distributor.
Click to expand...
Below are pages from an IH manual showing the distributor, if you need it.
https://farmallcub.club/rudi/farmal...ry Ignition Packages for Tractors/Page-11.jpg

This page shows the point gap is .020"
Put oil in the end of the shaft the rotor is on, so the spark advance doesn't get stuck. While the distributor is on the engine, turn the rotor back and forth to see if the advance is free, the rotor only turns a small amount back and forth.

freebird said:
Hope I can find a 6v timing light cheap OR will a 12v work and maybe replace the bulb?
Click to expand...
Usually a 12 volt timing light works dim on 6 volts. You can connect a 12 volt timing light to a 12 volt battery, if you can bring one close enough for the wires to reach. Check the timing when there is not bright daylight, so you can see the marks better.
The 1956 LoBoy probably has 2 timing marks.
Below is a page from the Cub and LoBoy service manual showing where to set the timing at slow idle speed. Align mark 1 with the pointer. You can use white chalk and mark the marks on the pulley before running the engine.
Use only the picture, and the words under it, they are talking about other things on the page.
 
freebird said:
It is a 1956.

I did not do that I did one spark plug at a time and started the engine for each test. I'll have to re-test.

I will introduce seafoam to the crankcase. I am sure I have not put 120 hrs on it between oil changes.

Thank you for that info as I've ordered new points and condenser and plan on removing the distributor. Hope I can find a 6v timing light cheap OR will a 12v work and maybe replace the bulb?
Click to expand...
If you have a small 12V battery, you could hook it up to that and time the Cub. The timing lead has to be hooked up to #1 spark plug wire. The power does not have to come from the tractor. Riding mower for instance.
 
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I think the compression pressure for all LoBoys is 120 lbs.
Below are pages from an IH service manual made in 1955, it says the compression is 120 lbs at 240 RPM cranking speed, for engines serial number 196900 and above.
The LoBoy serial numbers start at 501, but I think the engine serial numbers begin where Farmall Cub engine serial numbers were then. Maybe Jim B. will say if this is right.

https://farmallcub.club/rudi/farmallcub.com/rudi_cub/www.cleancomputes.com/Cub/Blue Ribbon Service Manuals/GSS-1008 Specifications/Page 06.jpg

Check the engine serial number if you want to be sure. The number is stamped into the engine block, you may need to clean it, and use a light to see it.
Below is a page from the 1957 LoBoy operator's manual showing where the engine serial number is.
 
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Suggest this , I like to do a leak down test on engines . You get so much information.
Such as if 3,&4 valves are leaking you can hear it.
Leaking rings ,
Some auto parts rent them .
After the sea foam suggestion to work the engine at full operation temperature so the stuck rings will free up possibly.
 
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