Which Manifold (for the D)?

I've been looking for a different manifold (still debating dual exhaust or not) for my '47 D, and I found two online that are a bit different. (Not planning on buying either of these but want to know what to get when I do.) Why the differences? Is one an aftermarket? Did Deere change the pattern? Will either work on my D? My D is serial number 164224. I tried to read the casting number on the manifold that's on it, but I couldn't see it. Probably can when I take it off, but I'm cutting wood with it and don't wanna tear her apart just yet.

The first three pictures are one with part number D3412R and the last three are one with part number D1891R. Or so the listings say.

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D1891R is the typical all fuel manifold

D3412R is the Deere made manifold for GAS ENGINES ONLY.

Either would fit your D.

The gas manifold got rid of most the exhaust routing all around the intake for a cooler intake air/fuel mix.

If you went for the gas manifold, it might not run well on kero etc.

Hit up my email and I'll try to send you the parts book that would help you out tremendously for stuff like this
[email protected]
 
Awe shucks, guys. I have that parts book right on my shelf. How did I forget to look at it? Maybe cuz most of my machines are so old they don't have a parts
book. Least, that's me excuse. Sheesh. Sure can see how the intake has less exhaust/heat contact on the gas design--now that you point out the obvious.

But this leads me to wonder: did Deere make a D for gasoline only? High compression and all that? They did for the G, or at least a gas kit that raised the
horsepower quite a bit. I don't think either was tested at Nebraska that I can find.

Does the D gas manifold breathe easier and let the engine run cooler? Give it any more power? And would this be necessary or an improvement for the some-day when I switch to high compression pistons?

What's the story here?
 
I believe they did sell a kit to convert to gas, not sold out of the factory built that way. The cooler manifold and higher compression pistons. Running cooler? I doubt it, but the power would go up for sure. If you PLAN to put gas pistons in it the manifold is probably worth it. If you just throw it on without changing the compression, you may gain a little but not a lot. Never done it myself these are my best guesses
 
It looks like I could almost, just about, get the manifold off and back on without pulling the front of the tractor apart. Anybody here manage to do that?

Can't seem to lay my hands on my repair manual thingy, though it's about one step this side of worthless, with so many other tractors stuffed between the covers and not just the D. Not even sure it would show the steps. (Now where could I have left that??)
 
I need to look at my manual and tractor but I think you'll be taking off a lot to replace the manifold. It's on studs, and on the THIN chance you got the nuts off without twisting a stud,I don't think you can lift the manifold enough to clear the studs without hitting the fanshaft. The fanshaft is also a pain, but I need to look at my pictures to remember why. That means hood,and fuel tank at least. You might get lucky and not pull the rad but I can't remember the room available.
 
Actually starting in July 1951 JD did offer the D from the factory equipped for gasoline. Whether any were made or not is the question because by that time sales were almost nothing for the D.
 
Thanks. I'll probably need heat to get the nuts loose, so more room is better. Ugh on the fuel tank and fan shaft. Double ugh.
 
Interesting. Thanks. I wonder what they rated the HP for it or if they had to say the same as the all fuel model, since it wasn't tested at Nebraska.

I've always thought they should have continued developing the D instead of turning out that underdeveloped R with all its problems (no center bearing = broken cranks; PTO too weak; low power-to-weight ratio; enormous turning radius; horrible box seat with no spring; etc.). I mean, just having a high and low range like they put in the A, B and G would have been a huge improvement. Oh well. The world always moves on from what I think would have been right. Sigh.
 
A company in CANADA at one time named ROBIN manufacturing Carb / Manifolds designed for gasoline.
Pic is one of my D's....I also have a McCormick 15-30 with a ROBIN Gasoline conversion.
Bob..
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Interesting. Thank you very much for showing us. That one keeps the intake completely separate. Do you notice a horse power difference between the different manifolds if all else is the same?
 

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