1949 8n no power under load.

Well after waking up the old girl from her winter slumber she Is defiantly not right as of right now. I have her sounding like its running great but no power under a load. Example 4 gear or cultivating the ground with a spring tooth. It will just chug out and die or start missing with black smoke coming out the tailpipe.

Thought it was a electrical issue as I have had in the past so I started there. New points, cap rotor, coil an spark plugs. Wires are newer and are getting very good spark. I even double check all my plug gaps and points.

Then went to fuel. Cleaned the fuel bowl and carburetor. I checked for flow and seems to be good.

As of right now I can only think of 2 more ideas to check. Compression and governor. Any additional ideas would be greatly appreciated or situational knowledge.
 
See tip # 14 to check the governor.

When is the last time you checked the advance weights in the distributor? I'd say given the symptoms you're having that it's time for a check.
75 Tips
 
See if it is firing on all cylinders. With it running disconnect one spark plug wire at a time. Each time it should effect engine speed. Also make sure firing order is correct. Number 3 and 4 wires are easy to be reversed. Firing order is 1 2 4 3. Front of engine is #1.
 
Check your air filter. If it is mostly plugged it may let enough air through to sound good with no load but blow the black smoke under load as the butterfly plate on the carburetor opens in response to more load.
 
So after compression check they were within 10 of each other. I did notice that one spark plug was black stut all over it. Only one which was cylinder 4.

I took off the governor to inspect it. It has always had a slow leak. Which there was a crack in the housing. I am replacing the governor for that. As far as the weights and internals they all looked pretty good. Minimal wear.bearings wear round with no flat spots.

I'm at a loss right now. As far as a plugged filter I ran it without to double check with the same result. Any more ideas with the supplies info?
 
(quoted from post at 19:21:51 05/01/18) So after compression check they were within 10 of each other. I did notice that one spark plug was black stut all over it. Only one which was cylinder 4.

I took off the governor to inspect it. It has always had a slow leak. Which there was a crack in the housing. I am replacing the governor for that. As far as the weights and internals they all looked pretty good. Minimal wear.bearings wear round with no flat spots.

I'm at a loss right now. As far as a plugged filter I ran it without to double check with the same result. Any more ideas with the supplies info?

So you aren't interested in checking the advance weights?
 
So have you tried pulling one plug wire off at time Like others advised? what was your compression, within 10 of each other means little without knowing what was high and what was low. that sooty plug could be trying to tell you something.
 
Sorry Bruce. I thou ch hy you were originally talking about the governor. I checked the distributor weights when I put the new points in.
 
Yes. When idling I did at high rpm. I also
traced each wire. I don't have the best
compression tester always recorded a little
low by 10psi but it get the job done. Found
this out when comparing with another gauge.
So my lowest was 75 and my highest was 85.
Surprisingly the stuty plug was the 85.
 
So my lowest was 75 and my highest was 85

Minimum acceptable pressure is 90 lbs (dry) with the lowest reading within 75% of the highest so your readings are low but it could be how you obtained them. Below is the method I recommend when doing a compression test.

1. Bring the engine to operating temp and remove all 4 plugs.
2. Disconnect the air cleaner and fully open choke and throttle.
3. Crank it at least 5 compression strokes or until the gauge stops climbing and record the final reading.
4. Complete the test on remaining cylinders.
5. Now add a tablespoon of oil to the cylinder just prior to sampling and repeat the process.

Interpreting results of adding oil: +10psi increase good engine; +20psi increase normal engine; +30psi increase worn engine. Stated another way; an increase in wet readings rules out valves and suggests ring sealing problems - Either the rings are stuck or the engine is worn out and needs an overhaul. No increase means a burned or stuck exhaust valve or a failing head gasket.
 
This is great. I will check this as soon as I get my new governor. I noticed a crack in the housing. Internals seems all in very good shape.
 

I'd like to hop onto this thread as I am having the exact same problem with my 49 8N ( 6v / front mount ). Per my previous post, I did have a bad manifold & gasket with two leaks. Replaced this morning and have her running great without load. All I can do to pull my harrow in the garden. Had to replace coil last year, and did all the points & condenser and set static timing. All was running great before setting up for the winter months. First time out with bush-hog, I had obvious lack of power. I have a relatively new carb, and don't suspect the governor. HOWEVER, I checked my compression while I had the hood off this morning after running for 30 min with new plugs... 65, 55, 55, 67. Can't believe it even starts with 6v. Unfortunately, I failed to run the tests again adding some oil. I was only at 75 across all 4 when I got it in 2008, and have likely run it about 500 hours. Has always pulled a 1 bottom plow in hard Georgia clay and run the 5' bush-hog okay, so I figured I'd do nothing until I got to this point. Valve clearance is good, but have not removed head to check things out. I suppose I could have stuck rings?? May try some MMO in the cylinders for a few days?? Perhaps I'm just ready for a re-build. Thoughts??
 
Just a little update. I put the new governor on and there is no change. I am hoping that the valves or head gasket at this point is the issue. I will be doing the compression test bruce advised tonight. and most likely tearing the head off the motor. I will keep the updates coming for future use.
 
Minimum acceptable pressure is 90 lbs w/ the lowest pressure reading w/in 75% of the highest reading. Run the engine to operating temp, turn it off, remove all 4 plugs, remove the breather hose & make sure the choke and throttle are both open. Crank it at least 5 compression strokes or until the gauge stops moving. Write down the first compression reading (that is the valves seating) then write down the reading after 5 strokes or when it stops increasing. You should have two numbers for each cylinder. Then, add a tablespoon of oil to each cylinder & repeat the process, but you only need the final reading for each cylinder. Write down the results & post back for help figuring out what it all means.
75 Tips
 
Results are in.

Cylinder 1
First crank 71
Final 83
Oil added 89

Cylinder 2
First crank 52
Final 71
Oil added 81

Cylinder 4
First crank 62
Final 80
Oil added 91

Cylinder 3
First crank 52
Final 70
Oil added 79

I tore the head off to inspect and all the valves are moving freely with the updated adjustable lifters and seem to be seating well. Cylinder walls are perfect looking with no piston play. Cylinder 4 though looks like it had a lot more carbon build up on the exhaust valve than the others. I mean it was black. as of right now I have zero clue on what else to do.
 
With those compression numbers being so low, I think it's time for at least a ring job.

How confident are you in the accuracy of your compression gauge?

An engine leak down test would tell you exactly where you are losing compression.
 
(quoted from post at 10:29:11 05/09/18) With those compression numbers being so low, I think it's time for at least a ring job.

How confident are you in the accuracy of your compression gauge?

An engine leak down test would tell you exactly where you are losing compression.

I am not confident in the gauge accuracy. Its harbor freight. I was using it to see if I had an extreme variance from one cylinder to another. Last time I used it my friends higher end one read about 10 to 15 psi higher than mine. Proper way to do a leak down test?
 
Proper way to do a leak down test?
You will need a constant supply of compressed air and a leak down gauge to perform this test. For consistent readings, the compressor must be topped off and not building air pressure. One gauge measures compressed air going into the cylinder, while the other measures the percentage of air leaking out. The regulator controls supply air pressure for even test results.

mvphoto16211.jpg


[b:a46bd99c00]Test Procedures:[/b:a46bd99c00]
1. Remove the spark plugs and bring one cylinder at a time to TDC.
2. Block the engine from turning.
3. Connect gauge to spark plug hole.
4. Apply compressed air and adjust knob for a steady reading on both gauges. Use the same air pressure on all cylinders.
5. Listen for air leaks: Oil filler - rings. Tailpipe - exhaust valve. Carburetor - intake valve. Air bubbles in radiator may indicate head gasket or cracked block or head.
 

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