Briggs 12.5HP engine problems

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I'm stumped....but then this is literally the first engine I've gone into this much depth on.
Background:
Briggs 286707-0441-01 12.5 HP I/C Quiet engine that slept in a flood for a year. I grabbed it, drained the oil and fluids etc....replaced the carb with a chineasium one and it fired up and ran but SMOOOOOOKED like crazy. I also rewired it and new starter solenoid etc....but that's not really an issue with this part.
SOOOOOO
I decided on a learning experiment(I was only into it $200 at this point)
Decided to do rings and in order to do this.....CRACK open the case.

SO....I did. Drained oil, separated the crank case, etc. It was dirty mess in there but cleaning it all out of all the crude made me feel GREAT.

I slipped the piston out, honed the cylinder until 95% of the marks were not noticeable by finger touch. installed the NEW rings on the piston ensuring the ring gaps were 1/3 piston away from each other.

I should say that I removed the governor assembly and the camshaft which had the bottom valves fall out and I didn't catch which was which.....so assembled in revers and matched the little "o" of the Crank and the Camshaft to align timing.

Now after it's ALLLLLL back together I stick it back on the tractor assemble everything and go to fire it....1/4 crank and then stops.....WAAAAAAY to much compression. remove the spark plug, cranks over and over without problem.....spark plug back in....no crank.

I do my research....find out there is a "compression relief" on some Briggs engines.....I POUR over every parts diagram and manual I can find without fining anything associate with a relief on this engine, no little mechanism on the Camshaft at all.

So.....I didn't check the Valve clearance or lash etc as I didn't remove the head from the block.

What am I missing, and this will be the third time I've pulled this engine apart...lol Any help is appreciated as this is an old engine from a Husqvarna LTH-125 tractor.

THANKS!!!
 

Hammermechanicman

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I slipped the piston out, honed the cylinder until 95% of the marks were not noticeable by finger touch. installed the NEW rings on the piston ensuring the ring gaps were 1/3 piston away from each other.

So.....I didn't check the Valve clearance or lash etc as I didn't remove the head from the block.
_______________________________________

What kind of hone? What type of stones? What grit? Did you put a 45 degree crosshatch pattern on the cylinder? Never seen someone hone a cylinder with the head on.
If i were to take a SWAG at the problem i would say you have oil up past the rings causing hydro lock. Take the head off and see if you have oil in it.
 
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it's an L head or flat head, not a OHV engine. I had the head off the cylinder but didn't remove the cylinder from the block only removed the piston from the cylinder and then honed it. I used medium stones on my power drill. Sorry I don't know what the different terminology are for things(head, head cover, valve cover, etc.) I removed the "valve cover" to show the combustion chamber, top of the piston and 2x valve tops).

I hadn't noticed any oil on top of the piston but did add a little to the rings before reassembly. If I were to guess it would be like less then a 1/4 teaspoon total on the cylinder walls and rings.

I have some issue with the compression relief on it I think I just can't figure out what that entails and how to fix it.....I may end up just disassembly and discarding the entire tractor at this rate....it is only a project without any reason lol

I plan on pulling the engine apart again and seeing what I can figure out just wanted to ask here to see what others have encountered.
 

Rivets

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If you removed the crankshaft and the camshaft, you probably dropped the lifters. When you reinstalled them you may have switched them around, changing the valve clearance. No matter what you do you will have to remove the valves and reset the valve clearances. Many DIY mechanics try to just switch the lifters, but 90% of the time they still have to reset the valve clearance.
 

ILENGINE

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Lets start with getting the terminology straight on an L head engines. The head is the part with the spark plug held on by 8-9 bolts. The valve cover is on the side of the engine with two 1/4 or 5/16 headed bolts and should have a rubber hose between it and the air intake side of the engine. You have to remove the valve cover to check the valve clearances and to remove the valve springs to grind the valve stem to set the valve clearances.

As far as compression release this engine may not have a mechanical release. More like a modified cam lobe that holds one of the valves open longer than it should allowing compression to bleed off before firing. This is a constant release happens every other engine revolution
 
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excellent and thank you.
Yes when I pulled the camshaft out the lifters fell out....actually more then once. they appeared to be the same length and size so I didn't really think much of it and just stuck them back in the way they came out. Is it possible that something else was stuck up the hole on the one that keeps the valve slightly open? I remember seeing a little "cap" type thing but couldn't figure out where it came from and it may have been from a different engine or something.

I'll pull it apart again and do the valve clearances......what do you do if you grind them down too far? lol I guess you learn a lesson and replace them.

This being my first foray into the world of small engine rebuilding it's been fun(and aggravating) to deal with a unit that was completely flood damaged. The oil looked like swamp water even after draining it out 2x.

Hopefully I can get it going again, I am having issues with the Hydro drive in it not wanting to do anything after my shitty attempt at a fluid change but that's another problem after the engine runs...lol
 

Rivets

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Grinding valve stems to adjust valve clearance by a DIY can take 15-30 minutes, if he has the patience to do it slowly. Get them to the low end of the tolerance (.004” intake .009” exhaust) and then reinstall with springs. I grind a little, then push down hard with my thumb and measure clearance hold tight as I can. When I reach low end I install. Usually I have to remove and do it again. May take a few try’s but patience is your friend. You must make sure the end is flat and square or your gap will be wrong. This manual may be of some help. https://drive.google.com/file/d/0B6NaqjIxWV1ycG8wd0s3Z2Q2X00/view
 
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thanks all, I'm feeling more and more like I can get this thing running again and well. I've had luck with another tractor rebuild I did and hoping this one goes well too.
 
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