Repowering 8199G

[daugen]

my 1986 Gravely is in good shape having been taken down to the frame by yours truly, but I have not touched the
750 original hour engine. It runs, makes decent power, but the dirty exhaust and chronically sticking points
are a pain. Does anyone here have experience with repowering with the 23hp Vanguard? They used to make a Honda repower
but that seems to have disappeared. I intend to keep this tractor forever, so I don't mind investing in it. It's used constantly for
field slope mowing, cart pulling, moving machinery with its ball hitch and blowing snow.
I have an ignition conversion kit I intend to install this winter when I have time, but that's only a patch.
pic of unit with my homemade rear weight box:
TractorData.com Gravely 8199-G tractor photos information
thanks
Drew

 

[gravelymay]

Hi Drew
The Honda is still a possibility

Honda 690cc GX Series V-Twin OHV Engine — Electric Start, Remote Throttle, Model# GX690RTDW | 601cc - 900cc Honda Horizontal Engines| Northern Tool + Equipment

Briggs are harder to seal off but will work

Call me If I can help 423 716 4611

Bruce g

 

[RichardTX]

I have done a few engine changes but I took the easy way out. I bought Onan 24 hp P224 engines and bolted it on. In essence I turned a 18G into a 24G and a 8129 into a 8249. Since Gravely already made tractors with Onan engines, sourcing an adapter plate was just a matter of patience and persistence.

I have paid anywhere from $300 - $700 for a good P224. Onan adapter plates have cost me anywhere from $15 to $45.

The second most expensive item when putting an engine on is the exhaust system. I think I spent about $175 for my exhaust systems including chrome muffler clamps. I went with stainless for the pipes. They should last almost forever. I could have put water pipe on, but to me that just looks really tacky.


A word of advice. When changing engines always measure the gear extension on the engine that you take off. Be precise and duplicate that amount on the replacement engine. Failure to do so may result in multiple engine removals to get it right.

Here is a picture of my 8249.

Tail pipes are too long and the muffler clamps not chrome, but that has since been rectified.

I am a big fan of Onan engines. I tore down the 3000 hour P224 that is on my 24G because it was starting to smoke. I got out my micrometers and measured everything. Apart from the rings, nothing else was worn. It all met factory specs. I micro-honed the cylinders, put in a new set of rings and put it together. It is now good for another 3000 hours.

 

[daugen]

Bruce and Richard thank you. All of these engines are good, and while I like the "mini-Harley" rump of the Vanguard, the Honda is very smooth, and obviously high quality.
The Onans get bashed for high parts cost, but...if you maintain them, how many parts does one really have to buy?... I love the unique Onan sound. I don't have the skills to do this
but based on availability of those adapter plates, that will likely drive my decision. Of course a nice V4 Wisconsin would be a hoot...but now that's dreaming.
thanks Drew

 

[RichardTX]

The Onans get bashed for high parts cost...

And the fact of the matter is that Onan engine parts are actually cheaper than Kohler. Price out pistons or a crankshaft for a Kohler M20 and compare that to Onan's price on a P224. Kohler wants $800 for a M20 crankshaft. The last Onan crankshafts I bought cost me a whopping $125 each. Briggs is higher than Onan too.

About the only thing that is pricey on the older Onan's is parts for the Marvel carbs and some of the Prestolite electrical parts. Then again, what do you expect from a company that made aircraft carbs? On the later Onan engines, Nikki 6100 carbs were used. New Nikki carbs are about $125. The starters on the later Onans are made by Mitsubishi. I forget what the model number is but they are used in all manner of things.

 

[RichardTX]

If you want to sell the B48 engine on that 8199, let me know. I have a home for it.

 

[daugen]

I'll remember that, thanks
here is a favorite pic of mine during renovation, I call it "fins"

 

[RichardTX]

I'll remember that, thanks
here is a favorite pic of mine during renovation, I call it "fins"

I call it "will overheat" if run that way.

 

[daugen]

of course, this was during renovation. Without the shrouds on, I'd cook it, like you said. The fins were a mess, clogged with mud, almost like the prior owner went mudding with it, which I knew he didn't. Likely caused by oil and dirt, the oil from too much blowby caused by that tiny vent filter being clogged. So I cleaned them out carefully, and repainted sparingly. Love this machine, one of my favorites. I've put the newer model muffler on, which quieted it down a tiny bit, and a nice chrome extension completed the job. I think it sounds better, but likely all in my head. If they had put the points on this machine in a more accessible place, like on the single Kohlers, I would probably live with it. This winter I'm going to install Kirk's electronic conversion and see if that helps. Hate to get rid of an engine that works, but when it won't start with stuck points from sitting for a few weeks, it just drives me nuts.

btw, your Onan looks super. The 24G was always the one I drooled over, didn't they put a Subaru engine in that too? A guy locally, who I bought the snowblower for it from, has a 24G with a Johnny Bucket on front, a very nice setup.

 

[RichardTX]

btw, your Onan looks super. The 24G was always the one I drooled over, didn't they put a Subaru engine in that too? A guy locally, who I bought the snowblower for it from, has a 24G with a Johnny Bucket on front, a very nice setup.

That's no 24G. That is a 8129 that I put a Onan P224 on thus creating a "8249". I have a 24G. I also have a 16G that I turned into a "24GLX" by installing a P224. The LX means Lightweight eXperimental.

I know of no Subaru engines installed on the 4 wheel tractors from the factory.

Stuck points? That is bizarre. I have yet to see that on any engine. I assume they are sticking open. If it were mine I would get another set, make sure that they are lubricated and try that. I would also make sure that the replacement points are OEM and that the point cover is sealed.

 

[daugen]

Richard, I've had to take a wooden dowel and gently tap with a rubber hammer on the points case, and that usually worked. Come to think of it, last time it was serviced they replaced the pushrod along with the points, and I've not had the problem since. Hmmmm.

And....my bad, it was not a 24G I saw with a Subaru V twin, but rather a 20G. Found the picture, too bad I didn't get one from the rear. Sure liked his Johnny Bucket. I bought this guy's snowblower for my 8199G.

btw, I took one ride with the chains on, scratched the heck out of my driveway, took them off, built a weight box with 300 pounds in it, and it ran marvelously.

 

[RichardTX]

Chains will scratch a driveway but when the snow gets deep, nothing beats their traction.

 

[daugen]

well....I may have done myself in here yesterday. Last mow job of the year, cutting down a lady's "wild meadow", i.e. messy weed patch, and I got into a large area of what I think is milkweed. It was like snow all around me, and I didn't think much of it, dumb me, until I started smelling something and shortly thereafter the engine died. To my serious dismay, smoke is pouring out of the engine, everything is clogged tight with the cottony fluff from the plant, and I really overheated the engine. The gasoline in my clear gas filter was boiling...I blew it all clean with my portable blower, and thank goodness nothing lit off. Let it cool down and would not start, though it spun freely. Expect I cooked either the condenser or the coil. Will pull all the engine shrouds and make sure there isn't any junk in there, which there sure wasn't before I started. Feel bad breaking my machine, not its fault but mine, but with the engine out of sight back there, I just didn't see what was going on nor did I expect it to clog that quickly, in under an hour of mowing. Air cleaner clogged too, with a pile of seeds in one corner. But the clogged intake grill was what did me in, no air getting to the engine so no surprise it cooked. Hopefully I didn't screw up the head, but it turned over fine with no strange noises. Going to replace the fuel lines just in case, can't imagine that kind of heat didn't damage the ones right on the engine. Bummer.

 

[hawkeye08]

I've had a couple of coils go out on my Onan engines on my Gravely riders from getting too hot I expect. Not cheap, around $100 IIRC.. I have a Gravely 816S that I replaced the original Onan with a newer P18 several years ago. It was very expensive for a new engine, never heard of craigslist or ebay back then... It died (will not even turn over) this last summer while pulling a sprayer... I did not have time to deal with it so walked home and got one of the other Gravely riders to finish the job. Reading this thread reminded me that I need to have a look at it and figure out what is wrong... I have 3 Gravely riders, I'm going to move some parts around, end up with two that run well, then sell the 3rd one with a loader.

Hope you find out good news on your cooked engine. Perhaps a digital gauge from a racing kart would work for you. I had a kart 20 years ago that had rpm and temp. A single wire wrapped around spark plug wire for RPM, temp was a thermocouple thing that was like a washer under the spark plug or one of the head bolts, I don't remember which...

 

[daugen]

I hope to get the details today, but the dealer called yesterday and said they got it running, after installing Kirk's twin coil and electronic conversion kit, so it must have been, as I sorta expected, an electrical melt down. Not sure if they took the head off, but it appears that some electrical part acted like a thermal fuse and died for my sins, thankfully. When I get the Gravely back, I'll take pics of the conversion and post them here. The coil is shaped totally different so I'm curious, to say the least, how they installed it.

Hawkeye, I've seen, somewhere, the spark plug heat sensor, and wasn't sure it was what I needed. Sure would like something that bolted into the top of the head, but maybe that spot is as good as it's going to get. I do have the tach/hour meter with the wire around the spark plug btw, it works fine, though seems a little slow in reaction time. I am rebuilding an old CC 125 and got the analog tach for that, boy would I like one of those on the Gravely. And a temp gauge right next to it...and yes, an overheat light/buzzer would be smart too.

After this little learning experience, I'm going to try to rig up an open mesh filter that attaches to the rear engine guard, and that hopefully will collect some of the chaff flying around. Not a lot of space in there, but if I removed the stock
screen wiper, I might be able to rig up something helpful. Plus maybe an electric fan too... good winter project.

 

[daugen]

a tardy update. It runs fine with the new ignition system. No backfiring or weirdness, but still rolls at idle.

I've hunted around the internet as much as I can, and have seen two or three engines put on the back of Gravely tractors.
What interests me is the Subaru V twin, 23hp since it seems to be more compact than others. Also, I like Subaru as an engine co.
Honda too, a nice 690 back there would do, but I always see if the US stuff is available first. So here's Kohler's best EFI:
Kohler Engines: Engines: Command PRO EFI

none of which look like they could remotely fit, adapter plate or not, without at least ditching the Donaldson style filter.

but while pondering this page, I wondered...just how much hp could the Gravely take? I have rugged HDAP tires on the back, and they
can put the hp to the ground. I know the riders went up to 24hp. I wonder what the design could reasonably take, understanding that more hp
might reduce clutch life. But the mechanical part seems very robust. As is the rear end. So how high could we go? 26-28-30 hp? I wonder who
has tried...

 

[daugen]

I have a Gravely 816S that I replaced the original Onan with a newer P18 several years ago. It was very expensive for a new engine, never heard of craigslist or ebay back then... It died (will not even turn over) this last summer while pulling a sprayer... I did not have time to deal with it

I would be very interested to know why a low hour Onan conked out on you. Was this a winter project for you? Drew