M274A1 4 Cylinder Smoking, Low power

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PRueff
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M274A1 4 Cylinder Smoking, Low power

Post by PRueff » Wed Nov 13, 2019 9:21 am

Greeting all! I am a new member to the forum, looking for advice.

I recently acquired a 1964 M274A1 with a 4 cylinder Willy’s Engine, it has been sitting for many years…(10+)

After following the excellent advice from this forum, I performed the following maintentance before trying to fire it up.

Replaced Engine Oil (Fuel in the crankcase led to pump rebuild)
Fuel Pump Rebuilt
4 New Spark Plugs
Drained and cleaned out fuel Tank
New Fuel Filter
New “in tank” fuel strainer/pick up module
New Carburetor
New Air Cleaner Element
Injected oil into cylinders and manually rotated engine

The Magneto breaker points were dirty, so I cleaned them up and set gap to .016

The Engine did start, however I am concerned with smoking from both banks of the engine.(Even after oil/fuel burn out time passed, 15-20 minutes)

It will smoke at start up and intermittently while running. The engine power seems underpowered.

Obvious wear on Valves or cylinder rings could be the culprit, but I was hoping to try and glean some tune-up tips from you on this machine before I tear into the engine.

Questions:
1) Magneto Timing. I read the TM manual, but it seems to leave details out like how to know where the gears on the rotor and the magneto should line up? The thing is running, but I would like to know with certainty that I have it timed dead on.
2) Carburetor and Governor Tuning. Again, the manual explains certain steps, but anything you guys can provide here would be great.
3) Cylinder Compression test. I will be performing a compression test on all cylinders this weekend, what numbers are acceptable?
4) Ignition timing light. My automotive inductive timing light clamp wont fit around the "huge" ignition wires coming from the mag, Is there a workaround anyone can advise me on this matter?

Also:
Interestingly, during the last outing the engine idle began to race and then the engine died after it had been running for 20 minutes or so, while being parked on a portion of my driveway which has a slight incline... It would not start afterwards and I had to tow it back to the garage. Any ideas what that was all about?

Thank you in advance for your assistance with my new toy!

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Re: M274A1 4 Cylinder Smoking, Low power

Post by Jeeps4Brains » Fri Nov 15, 2019 7:22 am

If it has sat that long the rings may need to re-seat as it is runs for awhile. That is if they are not too worn.
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Re: M274A1 4 Cylinder Smoking, Low power

Post by PRueff » Fri Nov 15, 2019 9:22 am

I will see how she settles in after a few outings. Seems like the seals in the trans and axles are leaking too, not a lot but leaving spots on the floor overnight. It may need a complete going through.

Thanks for all the input guys!

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Re: M274A1 4 Cylinder Smoking, Low power

Post by eclipse » Fri Nov 15, 2019 5:11 pm

125# is ideal compression in the 2 cylinder. Don't know the Willys engine for certain.
The adaptor from the wheeled vehicle electrical test set will allow easy timing with a light.
Do you have the TM specifically for the Willys engine? Or just the M274 TM? They are all available online for download. I found the link here somewhere.
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Re: M274A1 4 Cylinder Smoking, Low power

Post by muleman7 » Sat Nov 16, 2019 9:52 pm

Phil

You are in a very unique brotherhood that owns and runs the AO-4-53 series 2 4cyl mule engine.

I would run Rislone about 1 cup to 1 pint in the oil to help clean the engine and any rings that may be sticking. If the valve guides are beyond rebuild limits the they must be replaced or knurled and reamed to restore to specs. This should help stop the smoking after a period of running if the engine is in specs.

If your engine is running with good compression then a general run in should solve your smoking and running issues. The governor and carb adjustments should be preformed when the engine reaches operating temps and there is little adjustment that can be made other than 1-air fuel mixture at idle, 2-idle speed adjustment, 3-gov to carb control rod adjustment if any and 4-gov low and high speed settings. the High speed for the series 2 engine in the M274-A1 is 3650 rpms. The M274 series 1 engine was 4300 rpms. the series 1 engines compression ratio is 6.5 to 1 the same as the 2 cyl mule engine and it runs about 125 psi.

I hope the following information helps.

The valve clearance (cold engine) is 0.008-0.009 in
Magneto breaker point gap is 0.008-0.012 in, preferably nearer the 0.008 dimension
Spark plug gap is 0.023-0.028

OD of Valve Stem 0.2787 to 0.2792 Wear limit 0.2783
ID of Intake Valve Guide 0.2807 to 0.2817 Wear limit 0.2820
Fit of Valve Stem in Intake Valve Guide 0.0015L to 0.003L Wear limit 0.0037L
Fit of Valve Stem in Exhaust Valve Guide 0.003L to 0.005L Wear limit 0.006L
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Re: M274A1 4 Cylinder Smoking, Low power

Post by Grummanflyer » Sat Nov 16, 2019 11:55 pm

"Also:
Interestingly, during the last outing the engine idle began to race and then the engine died after it had been running for 20 minutes or so, while being parked on a portion of my driveway which has a slight incline... It would not start afterwards and I had to tow it back to the garage. Any ideas what that was all about?

Thank you in advance for your assistance with my new toy!
[/quote]"

When engine RPM increases before the engine dies, it's an indication that the mixture leaned out to the point that there was no longer enough fuel to support combustion. Typically a slightly rich mixture is necessary at idle because lean mixtures burn slower than rich mixtures and an excessively lean mixture may result in backfire thru the carb. Sounds to me like your mule died from fuel starvation although with all the work you did that seems strange unless it was running really really rich already. It would be a simple matter to squirt some carb cleaner or fuel in the intake tube and see if it tries to hit.
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