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Discussion Starter #1
The last few times I have gotten my M out, I have noticed white smoke coming out of the stack for the first minute or so. Not pouring out in clouds, just little puffs. If I warm it up with the lower radiator hose, the smoke is much worse. It definitely smells like coolant too. I haven't run it long or hard enough to notice if it is also burning coolant while operating.

I am assuming a bad head gasket unless someone has any other ideas.

I know none of the tractor's past history so while I'm in there I figured I could/should take care of anything else that could cause a problem later on while I already have it appart. I got a complete upper end gasket kit and a new exhaust manifold. But I've never had a Dubuque 2-cylinder opened up before and I was wondering if there was anything specific to the vertical 2-cylinder engine that I should be watching for? Other than needing its yearly changing of the spark plugs, it runs like a champ and pulls really strong.
 

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Discussion Starter #2
What are your thoughts on polishing the passages on the inside of the intake/exhaust manifold?

How about polishing the intake and exhaust passages in the head?

Does my engine even turn fast enough for polishing anything to have any effect at all?

This will never be a pulling tractor. The only competition it will ever be in is a constant struggle against the passage of time. Most of what my tractor gets used for is plowing snow, mowing grass, and cultivating the garden. Other than running the mower, it spends most of the time at half throttle or less.
 

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I wouldn't do it. You actually benefit from some roughness in the intake manifold on a carbureted engine. It creates some turbulence which mixes the air/fuel mixture better. These engines turn at such a low RPM that you wouldn't really see any benefit anyway.
 

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Discussion Starter #4
That's what I was thinking too. Rough casting = more even fuel air mixture.

The exhaust bore is as big as you'd expect to see on a 6,000 rpm v8... Except that it is on a 1,100 rpm two-cylinder. So I can't really see benefit there either especially since I'm ditching the baffled muffler in favor of a straight pipe.

I just figured I would ask... Even a 5% power increase is significant when you only start with 20 horsepower! :good2: Not that I need the extra power, but more is usually better. I figure the chrome on the new stack will add at least one or two horsepower just based on how bright it shines. :lol:
 

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while you have the head off why not shave it to raise compression some. even half a point would be good and cheap:greentractorride:
 

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Discussion Starter #6
I've thought of that too. I don't think that I'll intentionally shave the head, but I will at least true it out. Any material removed should bump the compression up at least a little bit.

Sometimes it seems like the compression of these old two-cylinders was limited more by that eras starter's ability to roll them over than anything else. Since I went to the 12volt system a few years ago, it has a lot more cranking power than before.


Right now my biggest problem is that I can't find my shop manual which contains all of the torque specs needed for re-assembly. When we moved last fall I remember putting it in a box and then labeling the box "also contains tractor manuals". We have a few remaining boxes, but that one isn't one of them. When we un-packed we had a couple of friends over to help and I'm wondering if the manual ended up somewhere weird because whoever un-boxed it didn't know what else to do with it. :banghead::nunu:
 

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I've thought of that too. I don't think that I'll intentionally shave the head, but I will at least true it out. Any material removed should bump the compression up at least a little bit.

Sometimes it seems like the compression of these old two-cylinders was limited more by that eras starter's ability to roll them over than anything else. Since I went to the 12volt system a few years ago, it has a lot more cranking power than before.


Right now my biggest problem is that I can't find my shop manual which contains all of the torque specs needed for re-assembly. When we moved last fall I remember putting it in a box and then labeling the box "also contains tractor manuals". We have a few remaining boxes, but that one isn't one of them. When we un-packed we had a couple of friends over to help and I'm wondering if the manual ended up somewhere weird because whoever un-boxed it didn't know what else to do with it. :banghead::nunu:

have the head shaved and the combustion chambers smoothed out. you dont want any roughness in the combustion chamber or edges to create hot spots and cause detination at any ratio. i think those only had a 6:1 compression ratio anyway a 6.5:1 would be good and safe with a stock gasket and good head bolts would bump up the low end tourqe for not much coin:greentractorride:
 

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Discussion Starter #9
According to JD Service manual 03-55 head bolts torqued 100-110 ft lbs.

Sent from my GT-P5113 using Tapatalk
Thank you! :hi: We had company over today so I was forced into being social and not allowed to run off to search in the basement.

If you could also give me the specs on the intake/exhaust manifold, I'd really appreciate it! I don't think I'll have to take off the upper water pipe or anything else, but it might be handy to have on hand as well. :bigbeer:

Moving sucks. I don't recommend it unless it is completely necessary.
 

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No torque requirements noted in service manual for water manifold or intake/exhaust manifold. Only noted to tighten securely!

Sent from my GT-P5113 using Tapatalk
 

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Discussion Starter #11
No torque requirements noted in service manual for water manifold or intake/exhaust manifold. Only noted to tighten securely!
This is why I love old equipment! I am a big fan of the "tighten it until it's good enough" way of thinking.

:bigthumb::cheers:

Thanks again!
 

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No torque requirements noted in service manual for water manifold or intake/exhaust manifold. Only noted to tighten securely!

Sent from my GT-P5113 using Tapatalk
got a deere full service manual for my 35' D and it indeed says just to tighten most bolts tightly. guess farmers did not carry tourqe wrenches with them into the field:dunno: lol
 

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Discussion Starter #13
I would question the accuracy of a 1930's era torque wrench anyway.

And, knowing the mind of a farmer the way I do, the logic would probably be "if 80 ft-lbs is good, 180 ft-lbs is tighter so it must be better"... Sometimes it is better to just be a little vague than to give a specific number.
 

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Discussion Starter #15
I have their three-piece manual set for my M and yes, they are top quality books that I would recommend to anyone who has an old machine of any make or model.

What I really need to find that are even more important are a bunch of my own handwritten notes pertaining specifically to my model M and the modifications I've made to it as well as a handful of modern part number equivalents which are stashed inside the manuals. Plus, the same box had the manuals for my old Sears, Deere14sb push-mower, chain-saw, string trimmer, and most of my attachments.

I know I put the box on the truck, I just have to find where it went after it was unloaded.
 
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