Gloom, despair, and agony on......you.
It would be of some help to know exactly which Briggs engine you are working on. Model and type numbers please.
As to the relative positions/actions of valve to piston ON A PROPERLY TIMED crank & cam, AND..... while turning the engine in the correct direction of rotation:
Beginning with the onset of the INTAKE stroke, Piston at or slightly past TDC, Exhaust valve is fully seated, or CLOSED (the rocker is not pushing valve down), the Intake valve is beginning to open (the rocker is pushing the valve down).
As the piston moves toward BDC, the Exhaust valve remains closed and the Intake valve remains open.
As the crank passes BDC and the piston begins to rise marks the onset of the COMPRESSION stroke. At this time the Exhaust valve remains closed and the Intake valve begins to close. When the piston moves on to TDC, both valves remain closed.
This TDC point marks the onset of the POWER stroke. As the piston continues on toward BDC, both valves remain closed. As the crank moves further and passes BDC marks the onset of the EXHAUST stroke. The Exhaust valve will begin to open while the Intake valve remains closed. The exhaust valve will remain open and the Intake valve remains closed until the piston nears TDC, at which time a new Intake stroke begins. You also need to correlate the flywheel ignition timing into this process. Because the ignition is timed to the crankshaft, spark is created near TDC on the COMPRESSION stroke and the EXHAUST stroke (wasted spark). Observe the position of ignition magnet on the flywheel with respect to the ignition coil and the valve movements. I hope this is some help.

That helps alot. The engine is a 17.5hp single piston OHV, vertical shaft motor. The numbers on the engine are 31C707 0230 E1C as best as I can read them.

Keith

"I would like to find an adaptor that goes from the flange coming out of the engine into one of those round mufflers with the pipe threads on them. Does anybody make an adaptor for this?"

Yes, I did. There is a short adaptor for these engines that connects to a square muffler just about 1-1/2" straight out.

I am not too sure about your changing coils. I would check the coil that was originally on the 17.5 hp engine and see if it had a square hole punched thru the laminates, maybe 3/16" square. IF so, actually in any case, I would use the original coil and clean it up unless the mice ate thru the spark plug lead. A little rust on the laminates does not affect the magnetic flux which creates the spark

Speaking of spark, the flywheel needs to be turning about 800 rpm when the magnet passes the coil laminates.

Walt Conner

"Is there a way to check to ensure I didn't align the timing gear and camshaft 180 degrees out now that it is all reassembed?. The dots are supposed to be aligned with the piston at tdc but I am now questioning if I did it at bdc instead."

Oh, by the way, SHORT answer is, IF you aligned the timing marks when assembling, it is timed correctly period, otherwise, you are not likely to be able to tell one tooth off, there is no such thing as aligning the timing markes and being off 180 degrees.

Walt Conner

I think I found the adaptor that you are talking about. There are two part numbers. 794661 is 1.75" long and 496002 is 2.25" long. Unfortunatly that's another $25 into this engine to get it running. I'll have to order the parts today.

After I thought about the timing some more, you are correct in that it can only be set one way. I am used to automotive timing where the dots have to line up at TDC. I checked the valves last night and they appear to be working in the correct order. I was very carefull to get the dots lined up. I also set the valve lash at .006, 1/4" beyond TDC on the compression stroke. From what I read I think that is the correct position. Hopefully I should be good to go.

I double checked the coils against each other last night and they appear to be exactly the same. The "bad" coil had the spark plug boot missing and the spark plug end rusted solid to the plug. Thats the reason I chose to switch them.

The only thing on this engine that is still a little funny is the sound it makes when I rotate the crank around. It makes this sound like a goose honking. It isn't anything mechanical. It sounds like air moving within the case. The sound is coming from the breather area. I am guessing it is just because it doesn't have any oil in it at this point and is causing a funny echo. Any thoughts?

Keith

"Unfortunatly that's another $25 into this engine to get it running"

IF you are the least bit handy, you can make your own OR if money is a consideration, as it is with most of us, check the local scrape yard, local small small engine repair shop. Large shops do not want to mess with used parts, may find your muffler there also. A new muffler will be expensive.

I cut out a flange, welded it to a short pipe nipple with threads for one of the cheap screw on mufflers.

Walt Conner

Walt Conner

I found my muffler adapter at the local hardware store. It is what they call a pipe nipple, about 2.5 inches long, and they also sell the large nut, that must be used to keep the nipple tight in the block. And, the little round muffler screws right onto it! RJ

The problem is that it isn't that type of muffler. The block has an open round hole and two screw holes on either side of that for attachment. It is meant to take a flange, not threaded pipe. I could buy some plate and steel tubing and weld up my own but it will still cost me probably $15 in materials and a nights worth of work. Not worth it for $10 in savings. I already have a muffler for it. The 11hp motor that blew up has a muffler that mounted to a flange directly on the block. It was not an overhad valve engine so there was room for the muffler. With the valve cover and spark plug where it is on this 17hp block the muffler has to stick out about 2" to clear everything.

As a side note, the round screw on mufflers sold at home centers for $5 or so will not work with the bigger displacment motors. They are too restrictive and not sized properly for the engine. They are only supposed to be used on motors with 8hp or less.

Keith

Walt, tried to contact you about about a loose valve guide in a Briggs (24hp 446700) head but haven't heard regarding your fix. I had to get that project moving so I ordered a new head ($77) but I'd like to repair the old for a back-up.

e-mail:

stave at warwick dot net (Substitute for 'at' and 'dot') .

"As a side note, the round screw on mufflers sold at home centers for $5 or so will not work with the bigger displacment motors. They are too restrictive and not sized properly for the engine. They are only supposed to be used on motors with 8hp or less."

There are two sizes of these, don't buy at Walmart.

Walt Conner

We'll I got the motor started last night. It started right up in about a half turn of the crank and had plenty of power and a nice idle. Unfortunatly my cheapness beat me again. After running for about 4 or 5 minutes the engine started to smoke like crazy. We shut it off and found that 1) the breather tube became detached from the engine and allowed a bunch of oil to pour down the side and 2) that the majority of the smoke was coming from the muffler. When I did the rebuild I looked the head gasket over and although it wasn't new looking, it seemed to be ok. I re-installed it instead of replacing it. To investigate the smoking I pulled the head and the valves were full of oil. I took another look at the head gasket and found a nice big chunk missing between the push rod chamber and the cylinder. It looks like there was oil pouring right through there and into the hot cylinder causing all my smoke. Off to the parts store yet again for another gasket. Hoepfully this will be it.

Keith