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oldfarmkid

Good Leak Down Test percentages?

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Preformed cylinder leak down tests on my 1952 Super M today. Found that 10% or less is normal for new to near new car engines. Not able to find much other wise.

I think i'm pretty good, all results are an average of three tests on each cylinder. #1 = 14%, #2= 14%, #3 =15%, #4=16.5%.

What do you folks with more experience say.  Thanks

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Are you having any issues with the way it runs? I am guessing this is far from a new engine. I certainly would not be worried with those numbers unless there is an issue.

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No issues, just have never found factory compression numbers, which I would normally use to determine health of engine. Figured if no smoke, and good leak down numbers, all is well.

But then also no leak down percentage info either. After replacement of standard ignition parts, adjustment of valve gap, new points, and condenser set timing plus get mechanical advance working as it should. It starts quickly and runs very well. Problem is I grew up on a farm, and all family members were farmers. Before high school graduation writing was on the wall that small family farms were dying. So joined the Army and found a new way of life. I'm now retired and bringing some of my family history back to life with a couple of tractors similar to what I grew up with. As they say, all that said to say this. I'm a suburbanite  with no land to try tandem disking or plowing on. Those are real world tests that I would prefer to tell me the health of my project tractor. But all I have is road and road gear. Tractor has been worked hard. While oil pan was dropped noted pistons are aluminum, and have read it came from factory with steel pistons. So guessing engine work was preformed in the past. I know it might seem silly, but if I take it to a show and am offered a plow for plowing demonstration. Or, would you like to provide power to the threshing machine. I'd like to with confidence reply, heck yeah, can do. 

Thanks for your reply.

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As with a compression test the actual numbers don't mean much. Just so they are even. The bonus of a leak down test is listening at intake exhaust and crankcase to determine where leakage is at. You should have no leakage at either intake or exhaust.

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I doubt that IH published leakdown info back then.

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Yeah, agree with you. Never expected to find 67 year old factory leak down numbers. But a lot of sharp people work on old ag equipment and tractors, thought I could tap into that type of experience. Worked in the electronics, electricity, fields for 36 years. Told the techs I taught to go from an ok tech, to an outstanding tech, you have to make the invisible, visible. To do that use good test equipment and know how to use it. Know the difference between  a good reading and a band reading, and what to do about it. So I'm a test equipment hound, helps me to know what I have instead of what I hope I have. Have known mechanics that do almost everything by feel, sound, or smell. No meters, torque wrenches, or feeler gauges. I don't have that touch. When I've tried then checked with recommended equipment, I'm always way off.        

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Spinning the engine on the starter with the ignition off can tell how even the compression is, and let you hear any leaks.

 

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Yep, great example. Tells me starter works, and engine turns over,plus good battery. After that ???      

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Super M and Super H were the first tractors built at FARMALL with aluminum pistons.  But most 67 year old tractors have had new sleeves, pistons, and rings by now, and the valves ground, maybe even new main & rod and cam journal bearings.

Tractors built before the SM/SH used gray iron pistons. They were heavy, but were an excellent wearing piston.

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Took a while for me to find it, but a gasoline Super M should make 129 psi cranking compression.  All 4 plugs removed, throttle wide open,  loosen plugs a turn or two, reconnect plug wires, start and run engine for a minute or two, engine must be warm for an accurate test.  Remove all 4 plugs, install test gauge, crank for 5-6 rotations in each cylinder.

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Well Doc... here's my issue. It's a distillate model running on gas. When I first asked questions about the engine, the whole tractor became nothing but a joke so I make some final comments to end that discussion and thankfully the topic died. Thanks for your info, any ballpark guess on what HP at the drawbar is made with a distillate engine and head, tuned and running on gas? Compression has improved the more I run it. Last Hot compression tests indicated 100, 100,100,96. Can't find that Nebraska ever tested that combination. Though I did notice that either an M or Super-M distillate did out preform a standard gas model of the same model in one of the many pulling tests they preformed. 

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