Hi all,
We've just removed the engine from our 1923 Stanley 740. The bottom half of the engine looks as though it has been renovated fairly recently, as well as all the teeth on the gears. However, the cylinder block is very rusty and we need to remove the cylinder end and valve chest covers so as to check the valves and piston rings as they are suspected to be leaking. How do you remove the covers?
Also, what is the best way to reface the valves? Thanks for any feedback. George.

George, There is a lot to know about rebuilding a Stanley engine that is not covered in books. Also there is a bit too much to cover all of it here in just a few paragraphs. The slide valves have to go back into the same sides that they came out of and with the same side up as how they had been taken out. If they are not already marked for their location, I usually mark them with a die grinder. If they are flat and without scratches, leave them alone. The valve faces should be almost perfectly flat without any scratches across their faces. I reface my slide valves on an large flat surface oil stone. The valve port faces can be cleaned up by different means depending on how bad they are. For slight scratches, I have used a mill file at the first and moving onto emery paper glued on to a false slide valve. The false slide valve is moved evenly used across the whole port area. Next is bluing on the slide valves and the valve ports. Go through the valve movements to see where the high spots are. Address the high spots and repeat the bluing process until even contact covers both faces. From here, I lap the valves with valve lapping compound. Keep at it until there is a complete contact without any high spots on the faces. On reassembly, the valves should float freely on their valve stems without any lost motion. After valve face work, do not use hook up until the valves get lapped in with enough miles on them. With the heads, on reassembly, make sure that you return them to there original locations. The heads are usually marked with #1 or #2. To unscrew the heads, I used a soft driver and about a 16 ounce hammer to drive the heads around to unscrew them. If they will not move, I take a torch to the head and heat it up until color first starts to appear. Let them cool. When cold, they should have shrunk enough to be easily unscrewed. The steam chest cover also comes off the same way. Stuffing box packing is used for head gaskets for all of them. It hides in the last thread against the lip.

Thanks very much Pat, your method worked a treat. George.

Hi all,
Here's another question, when you put the valves back on the stems, how far should you tighten the nut up on the end and how much clearence should there be?
George.

If you are talking about the nut on the front of the valve stem, it should only be tightened enough to prevent lost motion with the slide valve, but still loose enought so that the valve can easily float on the valve stem. No clearance between the valve stem nut and the slide valve. Adjust just tight enough so that the valve can still foat on and off the valve seat. Adjusting the slide valves for proper valve lap is a whole another topic.

George check how wide the ends of the valve are. The 740 might have the more correct valves. If one end is wider than the other it goes toward the crank end. This is normally about 0.010 or a little more.
Rolly

Thanks Rolly and Pat for your replies, they are greatly appreciated. Today we tried to check that gap between the piston and cylinder wall with no rings on. WE found that one piston had 15 thou gap and the other 25 thou. My uncle who is a trained I.C mechanic suggested having the cyliner re-bored but with no liners and fit over size pistons with clupet spiral rings. My question is, is this gap actually tolerable and can we just hone and fit new rings or is a rebore and new piston neccessary? Thanks for any advice and sorry for asking so many questions. George.

Fifteen thousands of an inch piston clearance is still an OK fit. On a low speed Stanley steam engine like this and using the correct step gapped piston rings, it will still function very well. Usually the story doesn't stop here. The condition of the cylinder wall with deep pits, rusted areas, scratches, cylinder taper and out of round are all problems that should be honed out. Small pits can be overlooked. Once honed to a usable cylinder condition, if it is now beyond piston clearance limits, then it is time to make new pistons. A Stanley engine can still run with twenty thousands of an inch oversize clearance in the bore but for best performance, a smaller clearance is much more desirable. Your 25 thousands of an inch piston clearance is in need of attention. With this much clearance, piston slap can be a problem. That makes it tough especially on the piston rod packing. Liners are not an option in a Stanley engine without having to machine out the treads in one end of the bore. After the new liner has been installed, then welding back in the new cast iron and remachining its new threads can get costly. I have been there and done that. In taking the old pistons off of the piston rods, don't forget to first machine off the rivited over ends of the piston rods before unscrewing their pistons.

George

I rebuilt the cylinder end of my 10 hp Stanley engine last spring having rebuilt the crank end 3 years ago when a crank web broke. The main reason for me doing the cylinder end rebuild was to do away with the ball type cross head which can cause the piston rod to snap off where it joins the cross head resulting in a broken cylinder block when the piston hits the cylinder cover. Also the piston rods where a bit pitted and I needed to take up the glands every day on a tour and repack them once in the week. It now has hard chromed rods and bronze guide bars.

As I was fitting new piston rods I couldn’t reuse the old pistons as I would never have got them to run true. My cylinder bores were only 10 thou. out of round but with a Stanley being a horizontal engine all the wear and rust pitting takes place in the bottom of the cylinders. So when I rebored the cylinders I had to make sure they were bored on the original centre line and had to go to plus 40 thou. to get them to clean up.

My point is what are your rods like, could they do with being renewed as now is the time to do it. If you just hone the cylinders you will have difficulty getting them round and you will never get them back on centre, reboring is the only way to correct this.

I can highly recommend Clupet piston rings and they will make them to any size you wish.

Don

Hi Don,
The rods have been hard chromed and teh crank runs on modern roller bearings. The cross-head guides are made of bronze. The engine brace has been moderfied with the fitting of pieces of threaded bar with perforrated nuts so as to keep the cross-head guides parallel, as stanley's did on the model 740 (ours has a replacement 735 engine). The valve rods are also hard chromed although someone has got a pair of molegrips and tried to adjust them, thus scoring them, although the scoring doesn't go as far as the packing, so I've been told that should be alright! George.