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Discussion Starter #1 (Edited)
Hello everyone,
After searching for a answer to my question all over the net, this looks like the place to get answers when it comes to a john deere.
So I purchased a jd 318 awhile ago, and the engine has a bit of a knock to it. I'm almost positive that its a rod bearing knock. So with that said, I have a onan emerald 4000 watt generator with 50 hrs on it that has just sat in the shop for a couple of years. It has a P218 engine on it, and I believe my 1985 318 would be a B43. Would I be able to use the shortblock of the p218 engine and transplant everything from my b43 engine? The generator is basically brand new, and if the shortblock would work, would obviously save me quite a bit of cash lol.

I know by looking at the generator I would have to change the oil pan, and intake, but I'm not sure if the crankshaft is where I would run into a issue? I'm not sure if the p218's on a generator would have a tapered crank or not. Anyways I would appreciate any information you guys would be willing to share.

After looking at my post I realized I made a mistake. My JD 318 has a electronic ignition, so Im assuming that means its a p218, and the generator has points, so I'm thinking now after more research its a BGE. So basically question remains the same just in reverse order.
 

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You were right to come here for answers.Welcome!
This thread will likely get moved to the Hydrostatic Drive Tractors section because it is a technical question and a 318 is a hydrostatic drive tractor. There are others here like Boomer that can answer your question better than I so stay tuned!
 

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Discussion Starter #3
Sorry about that guys, Not really the way I wanted to introduce myself by posting to the wrong category. I'll be sure to pay better attention in the future.
 

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The P218 Onan was made with a multitude of crankshaft configurations and it is unlikely that the one in the generator is correct for your tractor. Here is the Performer parts catalog where you can look up the series number of the generator's engine and compare it to what the 318 needs.

View attachment Onan Performer Parts Catalog.pdf

Swapping a P218 from a later 318 with a B series in an earlier one would at least involve changing the flywheel (or driveshaft) and cutting the frame to clear the solenoid shift starter of the later P-series engine (or you could swap the engine pan and use the old starter...) Using a different series Onan with an incompatible crank contour and diameter would further complicate this to allow fitting the tractor's front PTO clutch assembly.

Chuck
 

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The crank is likely different to attach the drive shaft and pto clutch.
Not sure how different the wireing is from points to electronic ignition.
 

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Discussion Starter #7
After going through the manual that Chuck V posted I've come to the conclusion that there really isn't anyway to make the swap. About the only thing that seems to share the same part numbers is the connecting rods. Everything else seems to be different. It's a shame, as it would have been very nice to put that generator engine to work. I appreciate the help very much guys. It's fascinating how much knowledge you guys all have with John Deere's and there engines.
 

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It's fascinating how much knowledge you guys all have with John Deere's and there engines.
Like the saying goes: "you ain't seen nothing yet."

Stay tuned and keep asking questions
 
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Discussion Starter #10
Quick update and question on this engine again.
So I tore down the B43 that was on my 318 and after cleaning the block i noticed it had punched a crack into the aluminum, so the block has now become scrap, I have started taking apart my BGE engine that has been sitting forever and everything inside still looks like brand new. The only obvious difference I can see between the two motors is the crankshaft. Would I be able to simply swap a B43 crankshaft into this BGE onan and be okay? The main crank journals seem to mic out exactly the same as a B43, the Bore is also identical. The cam looks like its identical as well as the valves. so do you guys think I could get away with simply changing out the crank?
 

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bigblock
you need to compare cast # from the rods and camshaft
on both engines.
the 170-3140 cam is the one you want to use.

rods; 170-2916 170-3439 and 170-4444 are all for 2 5/8 stroke.
they MUST be used in matching pairs.

there may also be issues in the # of balls in the governor.

thank you. boomer ( the used onan engine parts guy, also NOS and new )
 

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Discussion Starter #12 (Edited)
Hi Boomer,
Quick question. I have a pair of brand new 112-0163 pistons, not sure why I have them or where they came from, but can I use those? I will be getting in contact with you next week for a set of rods.

Also, the cam shaft from the new block I want to use has skinnier valves, and camshaft number 170-4100 with 10 governor balls, Can I simply take out 5 governor balls, thus converting it to a 3600 rpm cam and governor? after taking the mic to both the old cam and new, It looks like the new cam has slightly higher lobes then the old one, or its just that the old one is that worn out.
 

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Discussion Starter #13
Changing the governor from 10 steel balls to 5 was actually pretty easy. If I would have went with the older cam, the cam lobes would not have been hitting the tappets like they should, they would have been hitting on the side.
 

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Discussion Starter #15 (Edited)
Hi Boomer,
The casting number from the new cam is 170-4100,
The casting number from my original cam is 170-2871


The block number from the new block is 170-4183 The pistons from the new block are also marked
112-0163
Which seems to be a P218G block, but what doesn't make any sense is the fact that it has points. So I"m wondering if this was one of the later blocks right before they switched over to electronic ignition?
This block was originally a onan emerald 4000 watt generator that was removed from a 1998 Motorhome.

I'm changing out the crank to a B48 crank I purchased off a JD420, and after researching if I am not mistaken I can use the rods from the generator which are 170-4105C, along with the pistons which are 112-0163, and the carb off a 420 as well to convert the engine to a 20hp. At this point my only real doubt is the camshaft that I will be using which was also off the generator "casting number
170-4100" that I took apart and converted to 3600RPM by removing 5 of the 10 steel balls.

Everything seems to be identical to a B43, with the exception of smaller diameter valves, meaning the valve stems are smaller in diameter but the valve head is the same diameter
The bore is measuring 3.250 which is also the same as the standard bore of my b43.




$_1.JPG
This isn't my engine but it is exactly what my generator engine looks like, only mine is using points. It has the same round boss toward the timing cover side of the block but not drilled through or machined to except whatever part that is on a P218G block.


And you stated that there is two different versions of the 112-0163 pistons, is there a simple way to tell which version I have? Because I will be ordering new Rings from you next week, along with cam and main bearings.

And lastly, would I need to use the heads from a B48 to fully convert to a 20hp? Or could I simply have my buddy at the machine shop mill the heads to get the compression up a bit? We mill the heads on big block chevys all the time, along with porting and polishing to get those extra hps out of the engine's, but is the HP gain from milling on a little engine like this even noticeable? I appreciate all your time answering what I consider dumb question's on this onan engine. Sadly this is out of the realm of my normal line of work.
Thanks, Big Block
 

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bigblock
the 170-2871 cam was used by the B 43E,( J.D. 316 )
and the 4.0 gen sets.
the cam is a piece of crap.

the 170-4100 is for P 216/218 and is MUCH
better than the 170-2871.

BUT, IF you want the 20 H.P. you need to use the 170-3140 cam, ( B43/48G )
or even better the P 220 cam. ( 170-4101 )

as to the heads,
the P 216,218 and 220 are all the same.
i would use them OVER the B 43/48G heads,better air flow
to the piston.

the 2 versions of the 0163 piston
both used the same ring set.

thank you. boomer
 
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