What is the correct procedure for finding TDC on L head engine for valve lapping? Engine is a 130297 model, made in 1983. It's a magnetron too.
Thanks
And by the way here is the engine. My first ever rebuild.
Because the residue lapping compound is going to find its way to the top ring, then the second ring and compression will be lost to a point it won't start. Keep a micrometer handy so when you tear it down you can measure the amount of wear in that approximate 2 hour period and keep in mind the ring grooves may have worn nearly an equal amount.
Stay with just a properly ground stone and forget the lapping compound. I know it "seems" good, but the grit is a factor unless the head is carefully washed and dried and reassembled. Hopefully any stone grit is also removed. Carbon bits are bad enough in scratching the bore. And the major source of "natures own" bore destruction- grit from the air intake.. My Intek air cleaner sealing surfaces are very hard to mate. I use a thin-thin coating of white grease on the (sponge) rubber surfaces and "read them" to be sure of a sealing surface. It has been written that over- zealous hand lapping can actually destroy a good seat/valve grind. Bluing left by a professional grinder is your friend. :2cents:
Senior's advise about ring land wear: Only a certain amount of combustion gas is supposed to get behind the rings and force them into contact with the bore. The oil film there is small. Enlarging the ring lands destroys their efficiency by making the rings too loose, promoting blowby. (citations and corrections welcomed).
Having rebuilt myself or supervised the rebuilding of hundreds of engines, I have never heard of reringing after two hours. It does not matter if it is a Briggs model A or Wisconsin VG4D, if done properly there is no reason to tear it down again. This does mean that you must wash your block after boring, glaze honing and lapping. Block must pass the Kleenex test before reassembly starts. Rubbing every part of the block with an oil dampened Kleenex will tell you if you missed anything. ANY evidence of dirt means rewash. This also teaches you the patience to take your time and do it right. Only time I've had to rebuild the same engine twice was an engine that came back 6 years later, it was a Kohler 341 used on a cement mixer. Doubt it was anything I did wrong or left behind. Motto to my students: "If you don't have time to do it right, you'll have to make time to do it over"
Wow, learned a lot on last 2 quotes. All I know is after I lapped\ground valves and deglazed cylinder wall, I cleaned block with a degreaser and ran block under outside water hose. Did not know anything about a kleenex test or reringning after 2 hours of running time. I will keep u posted on how engine runs. It is off my Troy Bilt pony tiller. Wish me luck!
You may not need rings being you used water. Years ago when lapping was more common it was so problematic that a special detergent was developed to use in conjunction with a scrub brush to clean the parts of residue. Today a car wash would be handy.
It was found that when using solvents of a petroleum nature the compound was not being removed well. I've personally seen it happen in 2 automobiles and several lawn mowers. One of the autos was a pickup I bought pre owned at a ford dealer. It wore the rings and ring grooves so bad the rings actually broke. Top ring in several pieces. That's when I discovered what that strange whistle sound was. I didn't know rings could whistle but they can. The tune is just mono tone and boring.
Here is hoping your cleaner overhaul will make a good engine.
More "cleanliness is next to Godliness"... Rivet's tip on the kleenex wipe reminds me of what I do to gasket surfaces before...e.g. RTV bead . A light colored clean tight weave rag ...spray brake cleaner on rag and rub until no more dark residue is removed. Keep repeating. You might be surprised how many applications it takes to see no more dark stain. (Crime stopper for the day) :laughing:
