Gas-Diesel engine swap question

[Soundguy]

if i replaced with a diesel.. i'd get one near the same specs.

you start dropping rpm and blade tip speed will suffer. on a finish quality lawnmower that ain't good.

hp is important too.. that 50" cut will suck it up.. I don't think you will be happy with a 10hp engine.

I'd look at a robin from the chinese store.. or similar, if I couldn't find a mower with a junked deck behind some mower shop.

soundguy

 

[handirifle]

Thanks for the replies and feedback/concerns. The deck, the body the frame and tires are in very good condition. Decals are shot but I could care less about them.

The HP issue was the main reason for the post. I just wasnt sure how much difference there was in torque. When it ran good this was a powerful motor and i really do not want lower. My 3 acres i mow are at times, suited more for a PTO power level but my ground stays wet too much to run a tractor. If i waited till it was dry enough for that the grass would be 5-6ft tall and CalFire would be all over me. They just passed me with flying colors, but gigged my neighbors.

I never said a diesel swap would be easier, i just thought a 10 hp one would be cheaper but now i know its not enough power.

As for other options, used mowers (which is what this was when i bought it) are a crap shoot i will not do again. I am looking at a min of $2,000 ffor a suitably sized replacement and more like 3K. In my area an apparent good used mower of 20hp or more will bring$ 1500 or more. At leastbwith this ond i know what i have. So will either repower this one or buy new. Have to think.
We are just now at Salem, OR (Amtrak), working our way to Seattle. When i get home i will most likely pull the engine and work on locating a replacement.

 

[Iplayfarmer]

... When i get home i will most likely pull the engine and work on locating a replacement.

If the rest of the machine is in good condition that's a good option. It will be cheaper than a new mower, and the grass will still look as good when you're done.

 

[Soundguy]

when I mentioned used one from behind a mower shop.. I meant to buy a used one with a shelled out deck / frame / running gear that might have a good engine. IE.. buying the parter solely for the engine.

quite common in tractor circles. Usually cheaper to find a machine with a blown engine to rob it's tranny, than it is to buy a tranny outright.. or vs/vs find a machine with a shelled tranny or rear for cheaper than just buying the engine by itself... etc.

soundguy

Thanks for the replies and feedback/concerns. The deck, the body the frame and tires are in very good condition. Decals are shot but I could care less about them.

The HP issue was the main reason for the post. I just wasnt sure how much difference there was in torque. When it ran good this was a powerful motor and i really do not want lower. My 3 acres i mow are at times, suited more for a PTO power level but my ground stays wet too much to run a tractor. If i waited till it was dry enough for that the grass would be 5-6ft tall and CalFire would be all over me. They just passed me with flying colors, but gigged my neighbors.

I never said a diesel swap would be easier, i just thought a 10 hp one would be cheaper but now i know its not enough power.

As for other options, used mowers (which is what this was when i bought it) are a crap shoot i will not do again. I am looking at a min of $2,000 ffor a suitably sized replacement and more like 3K. In my area an apparent good used mower of 20hp or more will bring$ 1500 or more. At leastbwith this ond i know what i have. So will either repower this one or buy new. Have to think.
We are just now at Salem, OR (Amtrak), working our way to Seattle. When i get home i will most likely pull the engine and work on locating a replacement.

 

[Iplayfarmer]

when I mentioned used one from behind a mower shop.. I meant to buy a used one with a shelled out deck / frame / running gear that might have a good engine. IE.. buying the parter solely for the engine.

quite common in tractor circles. Usually cheaper to find a machine with a blown engine to rob it's tranny, than it is to buy a tranny outright.. or vs/vs find a machine with a shelled tranny or rear for cheaper than just buying the engine by itself... etc.

soundguy

My thoughts, too. You'll get a shot mower with a good engine much cheaper and much easier than an engine alone.

 

[Soundguy]

fo sho

my old dodge truck, in it's condition, with it's milage and looks is worth about 300$.. maybee 500$ if bought at night by a blind person.

Or.. I could sell the wheels, still running but worn engine, tranny, rear end and front diffy, sell the bed, and brake controller.. all that parted out for 1200$

just ain't right.

same way with an old tractor.

a ford N is worth about 1200$ to 1500$ in average running condition with no major defects. or you can part it and get over 2000$ ( eventually )

 

[Iplayfarmer]

fo sho

my old dodge truck, in it's condition, with it's milage and looks is worth about 300$.. maybee 500$ if bought at night by a blind person.

Or.. I could sell the wheels, still running but worn engine, tranny, rear end and front diffy, sell the bed, and brake controller.. all that parted out for 1200$

just ain't right.

same way with an old tractor.

a ford N is worth about 1200$ to 1500$ in average running condition with no major defects. or you can part it and get over 2000$ ( eventually )

A guy I work with sold a truck to a parts yard. A few months later he needed a tranny from the same truck to fit one of his farm trucks. The tranny alone cost him more than he got for the truck, and it was HIS truck.

I tinker with old lawn mowers quite a bit. I can buy used mowers with almost no risk because worst case scenario I can part them out on e-bay. I have never lost money on a mower even if it is not repairable. Usually I can get my money back on just a few parts.

 

[IH3444]

21hp Briggs Gas....$570.00
Briggs & Stratton Engine Model: 331877-0036 on sale with free shipping from Tulsa Engine Warehouse!

Help Line....
http://www.tulsaenginewarehouse.com/catalog/repowerguide/repowerguide.htm

 

[handirifle]

As a comparison, the tulsa engine model that was linked is a single cyl, model, that most likely has much less torque. mine is a 750cc twin, and the alternator puts out 16 amps, compared to 9 from the linked motor. Not meaning to cut down the engine, but just to show why the replacements have been so pricey.

I spoke on the phone and through email with a rep from B&S and he didn't think I would be happy with the power from a single. The HP numbers don't give us enough info, sadly.

I assumed you meant for a parts mower, and I would do that IF I could find the right setup. Like I mentioned before, lots of guys here think theirs are gold plated, running or not. The best deals are for the ones that do not run....figures. I cannot even find someone selling an engine for a decent price, if at all.

If the new motor idea doesn't pan out, maybe I can part mine out to recoup my investment, at least partially.

 

[bxn]

Not sure if another reply mentioned it but you can send the old engine to a rebuilder.

I had my 40yo+ kohler k301 engine rebuilt and its still going strong.
If you can get a rebuilt carb all the better and might protect your new investment from cracked rings down the road.

The rebuilder usually restored old car engines and they did a nice job.

It was 500-600bucks for mine and it starts like new.

You can always get a nice new diesel in you next new tractor.
Then you`ll have a spare.

bxn

 

[handirifle]

The only issue with that is the engine is really NOT rebuildable. The valve seats are in the block (flat head engine) and the block is near destroyed where the seat goes. This would cost more than the whole tractor is worth for a machinist to do what I did the first time. That's why it's either some sort of new engine or new tractor.

 

[Soundguy]

The only issue with that is the engine is really NOT rebuildable. The valve seats are in the block (flat head engine) and the block is near destroyed where the seat goes. This would cost more than the whole tractor is worth for a machinist to do what I did the first time. That's why it's either some sort of new engine or new tractor.

aluminum block?

soundguy

 

[thomastractorsvc]

This past winter just did a rebuild on a 1985 John Deere 165 with Kawasaki engine, needed a new intake seat it had come loose and lost compression, cost $100 for the machine work they put an automotive valve seat, and ground the valve to match.

 

[handirifle]

I am on a train somewhere in Oregon, ssouthbound, so i cant access my laptop (using cell phone) anyway i cant post pics but yes it is alum block with steel seat. And the seat and valves are in the block,not the head so it is a MAJOR job to pull it and get it machined. I fixed it once myself (twice actually). First time wasnt too great but second time i thought it might last. I machined the block out and made a steel sleeve and inserted the seat into it. That worked fine for 3 or 4 mowings but of late has been runnning on one lung again. I will pull the head again to assess damage but am sure it will be the same or worse as before.

I will be home tomorrow and taking a look see.

 

[Soundguy]

valve in block is nothing new. flat head designs is what ford N's use..

I am on a train somewhere in Oregon, ssouthbound, so i cant access my laptop (using cell phone) anyway i cant post pics but yes it is alum block with steel seat. And the seat and valves are in the block,not the head so it is a MAJOR job to pull it and get it machined. I fixed it once myself (twice actually). First time wasnt too great but second time i thought it might last. I machined the block out and made a steel sleeve and inserted the seat into it. That worked fine for 3 or 4 mowings but of late has been runnning on one lung again. I will pull the head again to assess damage but am sure it will be the same or worse as before.

I will be home tomorrow and taking a look see.

 

[indianaEPH]

[

OK, that said, I was wondering how much horse power would be necessary in a diesel to replace the 20hp gas. I know it would operate at a slightly lower RPM, but I figure higher torque would offset that some.

[/QUOTE]

I almost hate to say this for fear of the replies it will get but, 20hp gas = 20 hp diesel = 20hp steam engine, albeit all with different operating speeds. If you are power limited on your current engine (that is you do using all of the power much of the time) then you will need 20hp in the new engine. It is likely the Diesel will have a better torque curve so it is more productive when lugging down but you will need to compare torque curves.

 

[Soundguy]

i agree. inasmuch as the funky way that lawnmower engines are rated in the optomYstic catgory the small diesel likely is to. so I wouldn't be shorting any hp to the machine expecting 20.. I would expect better low end torque when you hit a thick wad of grass. a couple percent less hp on the diesel should still net you the same 'work'.. IE.. like a ford 4cyl diesel vs a gasser of the same model.. diesel is a couple hp less, but performs in the same category... again.. a few percent.. perhaps 5.. IE.. I wouldn't use a diesel of less than 19hp in repalcing a 20hp gasser..

soundguy

 

[handirifle]

i agree. inasmuch as the funky way that lawnmower engines are rated in the optomYstic catgory the small diesel likely is to. so I wouldn't be shorting any hp to the machine expecting 20.. I would expect better low end torque when you hit a thick wad of grass. a couple percent less hp on the diesel should still net you the same 'work'.. IE.. like a ford 4cyl diesel vs a gasser of the same model.. diesel is a couple hp less, but performs in the same category... again.. a few percent.. perhaps 5.. IE.. I wouldn't use a diesel of less than 19hp in repalcing a 20hp gasser..

soundguy

Yea that seemed to be the consensus so my hopes (small) of a smaller diesel are out the window.

Soundguy
yea i know the flats are in fact a very old design, but in this case i was mentioning it because many folks think its a matter of taking a head to a machinist for repair. Its not so easy when you are talking about working with the whole block.
B&S informed me they never even made short blocks for this engine and no way would i invest in another used engine of the same type, at least without seeing the block first.

Am hoping when i get home i can do another" fix" till this fall. Otherwise i guess the grass will grow!

 

[Iplayfarmer]

Yea that seemed to be the consensus so my hopes (small) of a smaller diesel are out the window.

Soundguy
yea i know the flats are in fact a very old design, but in this case i was mentioning it because many folks think its a matter of taking a head to a machinist for repair. Its not so easy when you are talking about working with the whole block.
B&S informed me they never even made short blocks for this engine and no way would i invest in another used engine of the same type, at least without seeing the block first.

Am hoping when i get home i can do another" fix" till this fall. Otherwise i guess the grass will grow!

buy a goat

 

[Soundguy]

i'd see what a machinist could do... many of them work miracles with metal..

soundguy