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Farmall & IHC Tractors Discussion Forum
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1946 M - Low Compression????

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Fiddling Man

07-18-2006 18:40:11




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I have aquired a 1946 M that does not want to start with the starter. Battery is hot, starter rebuilt, new plugs, points, and condensor in magneto. New copper core plug wires. This tractor will run good if I pull or roll it off and it does not smoke. It just won't start on its own. I Compression tested all four cylinders today on a cold engine and they ranged from 60 to 70 PSI. Is this amount of compression to low? Could I have a carburetor problem? Stuck rings? It was used a lot over the years but it has been setting for the last three until recently. Do I just keep parking it on a hill and roll it off, or is it time for an overhaul? Suggestions?????

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Janicholson

07-19-2006 08:31:18




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 Re: 1946 M - Low Compression???? in reply to Fiddling Man, 07-18-2006 18:40:11  
One Item not mentioned in the posts below is the impulse coupling in the mag. If it is clicking loudly when cranking by hand, (or standing near the mag when electric starting) it should be ok, if not it might be jambed and this will cause no start at crank speeds. JimN



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Chad from Michigan

07-19-2006 07:35:35




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 Re: 1946 M - Low Compression???? in reply to Fiddling Man, 07-18-2006 18:40:11  
Just a thought
when you do your compression test do it dry and then put a shot of oil in each cylinder and if the compression jumps up by a lot the rings need to be seated or are junk. If it doesn't go up much you need to adjust your valves. As far as low yeah seems low but if you have the disalite head on it your going to be lower on compression anyway. My 44 H has 90lbs for compression across the board and that is good enough for me. You can also try sea foam in the gas and oil that help out a tractor of ours and I would use it again.
One other thing is try checking the timing I have found that on our Farmall A that dad could always pull start it or push it down a hill and it would fire right up and if you cranked it then it was uper hard starting. One day I reset the timing and it was off and when I cranked it then it fires right up. Just a few other things to check.
also make sure you have a good strong spark!
Chad

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the tractor vet

07-18-2006 20:32:56




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 Re: 1946 M - Low Compression???? in reply to Fiddling Man, 07-18-2006 18:40:11  
Yes this is vary low and will give ya hard start and low power . Myself i star to worry when they get down under a 100 .The reason it will start with a pull or a coast is that it is spining faster and it will make more comps. Now ya could cheat by making it a 12 volt system and put 12 volts thru the 6 volt starter. That will spin it faster and will help .



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CNKS

07-18-2006 19:40:50




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 Re: 1946 M - Low Compression???? in reply to Fiddling Man, 07-18-2006 18:40:11  
60-70 is low particularly if you have a gas (only) engine, but I don't know if it will keep it from starting. Did you have the throttle wide open when you checked it? That's easy to forget.



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Fiddle Man

07-19-2006 03:52:49




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 Re: 1946 M - Low Compression???? in reply to CNKS, 07-18-2006 19:40:50  
I don't remember opening the throttle before I checked the compression. I'll give it another shot today with the throttle wide open and see if there is any improvement. Thanks CNKS for the reminder.



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Magman

07-18-2006 18:48:40




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 Re: 1946 M - Low Compression???? in reply to Fiddling Man, 07-18-2006 18:40:11  
I think I would make sure all your conections are very clean, And are large enough for the system that is the ground and wire to the push button and starter. Then put some time on her get about 10 or more hours and good and hot see if the rings reseat them selfs and check the compression again, Also check for intake leaks and carb gasket leaks. Then maybe you can think about something else. JON

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Fiddle Man

07-19-2006 04:06:04




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 Re: 1946 M - Low Compression???? in reply to Magman, 07-18-2006 18:48:40  
I have cleaned all the connections. Based on past experience, the 6 volt battery spins the engine well enough that it should start without having to pull it off. Last night I squirted some Marvel Mystery oil into each cylinder. I'll let it set for a day and see if the compression comes up any with the throttle open. I'm hoping that maybe the rings are just stuck and need to be freed up to reseat. Fiddling with old iron is a joy and a pain in the #### at the same time!

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