wanted 18.5hp Briggs opposed twin

goodO1boydws

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Ive got a very high hour 1997 18.5hp Briggs opposed twin that I'd like to replace with the same KIND of engine, the opposed twin, rather than changing to an OHV engine if at all possible. The current one is using a lot of oil, evidently from cylinder wear mostly in one cylinder as the valves in both heads check out ok, and are set properly. That plug
is never as clean as the other one, and I've swapped them back and forth to double check for an ignition-related issue. I run narrow wire plugs that resist fouling better. I recently replaced the carb, and that helped with starting, but didn't change the oil consumption.

Its an I/C Twin II, specifically a 42D-777, type 128101, in a Poulan 46" 3-blade deck lawn tractor with the full length steel frame, and 23" rear tires
This chassis uses the symmetrical 2-hole muffler, the one that bolts directly to the frame,

I'm not married to it being an 18.5hp, as long as its AT LEAST 18.5hp, as I do a lot off hill mowing, use wheel weights and chains on wider tires and do considerable trailer hauling with it.

PLEASE let me know if you have something suitable.

thanks , Don
 

Tinkerer200

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Where do you live? You obviously had the heads off, what did the cylinder walls look like? I know where there is probably one in Robinson, IL but I don't think widow would ship, I wouldn't either. Pistons and rings for that are the same as for 28 series "L" head singles.
Walt Conner
 

goodO1boydws

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Thanks for the reply Tinkerer.

This is the original 1997 engine in a Poulan garden tractor, to which I added the ground-engaging-implement assembly. It gets in excess of 100 hours a year now, so that alone would be about 2500 hours. The first 10 years or so it was likely getting about double that as it was being used much more for things in addition to ordinary mowing like rough-cut mowing, hauling gravel, tilling, rock raking, and sweeping cut grass for composting and mulch. I even did a little garden soil plowing with it, but didn't have the right tires to do much of that-and it was only capable of doing shallow work. due to belt slippage and not enough weight. So my best guess (without an hour meter, one of which I have on the shelf but never got around to installing) is that it has something like 3500 hours on it.

I've worn through one mowing deck until, despite painting, coating, recoating, sandblasting and painting, coating, recoating and patching, it was like tinfoil in places, and replaced just about everything else on this machine at least once-some things multiple times, such as spindle assemblies, pulleys, steering gear assemblies, steering axle assembles, starters, carburetors, magnetos, wheel bearings, (plus tires belts blades, spark plugs, and filters of course), but it still has the original hydro and engine. Although I am using a heavier weight gear oil in the engine and hydro than it started with.

The last time I had the heads off they were carboned up of course, but they cleaned up same as always. (A long time ago I polished the heads inside to make cleaning easier and slow carbon buildup and also installed solid steel threaded spark plug inserts when one stripped.) There's been no significant difference in the valve or valve seats recently-with no evidence of overheating or cracks on the valves themselves. I've lapped the valves in their seats just a bit with valve grinding compound a couple times over the years to be sure they have decent seating surfaces,
The ridge was more pronounced on one cylinder than the other, with more wear on the bottom/ground facing cylinder sides as would be expected.

I've tried using different weights of single grade oil after having used Briggs 30wyt throughout the warranty period. As soon as the warranty ended I switched to Castrol 15w40 and ran that and an extra length filter until about 3-5 years ago, when oil consumption started to gradually increase. 40wt is consumed at about 1 to 1-12 ounces an hour, 15w40 at about 1-1/2-2 ounces ounces per hour, and 30wt about 2+ ounces per hour. That's if I use a GOOD oil, like Castrol or Rotella (which i use in our diesel tractors). I tried a tractor supply house's own brand of 30wt and that ran through at about 3 ounces per hour. I can deal with the 40wt and one ounce per hour consumption for about 2/3 of the year here but its getting to be a hassle and I think that this engine has earned its retirement. The tractor itself probably has too, but it has a lot of low hour parts on it now so........ .......

I should have included where we live in the first post-its East Tennessee, 37727.
 
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