Author Topic: Side Valve i.c. engine from Bar stock (Read 174846 times)

Brian Rupnow · « **Reply #125 on:** September 14, 2014, 08:54:54 AM »

Todays offering to the machining Gods is a piston. Granted, its a rather strange looking piston, and I have never built one like this before, but remember, we are in the wonderful world of prototype here. The top section of the piston extends up beyond the split between the combustion chamber and the cylinder, so we don't want it to contact the wall of the combustion chamber in that area. Additionally, there is more "hogging out" of material in the rod end of the cylinder than is usual. That is to accommodate the 1/4" sealed needle roller bearing, which is the smallest size I was able to buy. I'm not even certain a needle roller bearing is going to give us any great benefit there in terms of reducing friction, because the rod only swings in a small arc, not a full rotation.
I have to contact the manufacturers of the needle bearings on Monday, as I remember reading somewhere that needle bearings are made deliberately oversize, both on the outer diameter and on the inner diameter. They are intended to be press fitted into a housing, with a hard enough press fit to reduce the bore to the correct size.--That could be quite a trick, when they are going into an aluminum rod with only a thin band of material enclosing the bearings.

Brian Rupnow · « **Reply #126 on:** September 15, 2014, 09:07:35 AM »

I was getting ahead of myself!! Before I make the piston I have to lap the cylinder bore. Before I lap the cylinder bore I have to figure out a gasket to go between the cylinder and the combustion chamber and permanently lock them together. Before I do that I might as well make the valve cages and install them. So---These are the valve cages, which act not only as a seat for the valve to close against, but also as a guide for the valve stem. People have made these valve cages from many different materials, but I find that brass seems to work well, and an added advantage is that the brass cage, being softer than the steel valve, will "conform" to the shape of the valve face after the engine has been run for a short period of time, providing an excellent seal for compression.--And--If you do happen to screw up a valve seat, then you only have to replace this small item, not an entire cylinder head or whatever it is pressed into.

Brian Rupnow · « **Reply #127 on:** September 15, 2014, 12:00:03 PM »

Hmmmm---Everything I do has consequences--- I had to go out this morning to buy some brass to make valve cages out of. While I was out and about, I got thinking about the 0.197" diameter on the cages. Started thinking, that if I found out after the fact that the .197" diameter was too large to fit into a spring comfortably, there was no way to change it after it was pressed and Loctited into place. So---I stopped at the tool shop and bought a .197" diameter drill. Then I stopped at my fastener supplier and dug around in his spring collection. I ended up buying a pair of springs "INDUS0615125" They are a tight fit onto a .197" drill. Consequently, I will reduce that diameter on the cage drawing to .193" diameter. In the picture that is a .193" diameter drill setting inside the spring, and it fits well with no binding. The spring is wound from .023" diameter wire, has a pitch of .090 between the coils, and each spring is approximately 2" long, free length, but they will be cut down to a shorter length when I install them.

Brian Rupnow · « **Reply #128 on:** September 15, 2014, 03:05:53 PM »

So now we have a pair of valve cages installed. The first picture shows one of the semi-completed valve cages laying beside the cylinder, with the "pusher tool' that I use in my mechanics vice for pushing the cages into place. The valve seat is not cut yet in that picture, and the hole which lets fuel or exhaust enter/exit from the cages are not yet drilled.

Brian Rupnow · « **Reply #129 on:** September 15, 2014, 03:11:35 PM »

In these two pictures you can see the underside of the valve cages in one shot, and the top of the cylinder and valve cages in the other. In the shot showing the top of the cylinder, you can see my "George Britnell valve seat cutting tool". The seats are cut in that picture, but are hard to see because they are very small. They are cut by hand---no power tool involved.

Brian Rupnow · « **Reply #130 on:** September 15, 2014, 06:37:57 PM »

After letting the Loctite set up for a couple of hours on the pressed in valve cages (.0015" interference fit) I drilled the connecting holes thru from the carburetor and exhaust mounting surface to the center of the valve cages. Now my engine will be able to breath in and breath out-----------

Manxmodder · « **Reply #131 on:** September 15, 2014, 08:31:36 PM »

Looking better as every post you put up appears. I'm really looking forward to seeing you fire her up for the first time......OZ.

awemawson · « **Reply #132 on:** September 16, 2014, 02:12:45 AM »

I thought that loctite required a small clearance fit not an interference fit?

Manxmodder · « **Reply #133 on:** September 16, 2014, 07:01:13 AM »

Andrew, that depends on the surface finish on the component faces treated with loctite.

Years back when I was frequently involved in fitting press fit cylinder liners it was recommended practice to produce a honed crosshatch finish inside the cylinder block or barrel that the liner was being pressed into and use a low viscosity loctite retainer compound.

The loctite film occupied the small troughs in the honed surface......OZ.

Brian Rupnow · « **Reply #134 on:** September 16, 2014, 07:56:14 AM »

Sometime to day I hope to visit one of my suppliers and pick up some suitable head gasket material and some high temp sealing compound for the two bolts that have their heads exposed in the combustion chamber. I don't want to hone/lap the cylinder until after I have permanently locked the cast iron cylinder and the valve body (which I have been mistakenly been referring too as the "combustion chamber") together. In the meantime, I have just rattled off a quick detail of the valve. I see some people make valves out of stainless steel and other exotic materials, however I have always used just plain old garden variety cold rolled steel and never has a valve fail.

Brian Rupnow · « **Reply #135 on:** September 16, 2014, 08:05:03 AM »

And in case you are a bit confused about how this valve business goes together, here is a cross section thru the valves, cages, tappets, cams, etcetera.

Brian Rupnow · « **Reply #136 on:** September 16, 2014, 08:55:41 AM »

Oh Heck--While I'm setting here waiting for a call back about gasket material, I may as well put up a drawing of the valve keeper.

Brian Rupnow · « **Reply #137 on:** September 16, 2014, 02:32:00 PM »

We have valves and valve keepers!!! I had to order some gasket material and some extreme high temperature sealant and it won't be in until tomorrow, so in the interest of keeping things moving, I machined the valves and the keepers today. The valve on the right is open .080" which is the rise on the cam shaft, and the valve on the left is completely closed. Unlike an automobile engine, these valves set up a bit from the flat surface, even when they are closed.

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Brian Rupnow · « **Reply #138 on:** September 17, 2014, 08:33:58 AM »

If you guys remember back to when I made the crankshaft, there is a .563" diameter spacer ring on the back side of the web on each half of the crankshaft. This web is in there to maintain some clearance between the revolving crank web and the inside of the crankcase, as well as to locate the crankshaft so it doesn't float back and forth in the crankcase as the engine is running, making a clatter. Due to accumulated tolerances when machining, the thickness of this spacer ring invariably ends up either too thick or too thin. I have made it a separate piece Loctited into place on the crankshaft and here is why. Since my crankshaft is a two piece and comes apart in the center, I can make up this "setting master" fixture, insert the large end into the cylinder, and let the small end hang down into the crankcase and put the crankshaft "throw" through the 3/8" reamed hole. The small end at 0.531" is exactly the width I want between the webs of the crankshafts. Then a bit of careful measuring done by sliding each end of the crankshaft to its extreme travel in both directions should let me know exactly how thick these spacer rings should be made.

Brian Rupnow · « **Reply #139 on:** September 17, 2014, 09:52:32 AM »

Here is a picture of the Setting Tool in place. The cylinder fits over it and locates into the counterbore in top of the crankcase. I have made it and installed it and the results are about what I expected. Although the design calls for a 1/16" thick spacer on each side of the crankshaft to prevent endplay, in reality there is virtually no endplay in the driving side of the crankshaft, but it is still free to rotate. The other end of the crankshaft, the "follower" end will require a 1/32" spacer. Why the big difference from the design.--Well, mainly because of "stack up" of tolerances. There are a lot of pieces fitting together to give this theoretical 1/16" spacer on each side. Although I could have held all of my tolerances much closer when machining the parts, I doubt that I could ever had everything come out as a perfect match for the drawing. The 0.531" wide setting master will allow for a 1/2" wide connecting rod and a 1/64" brass or teflon spacer on each side of it between the webs.

Brian Rupnow · « **Reply #140 on:** September 17, 2014, 01:20:42 PM »

Today I'm just tidying up loose ends, so decided to machine the starter collar. This bolts onto the brass flywheel and lets me use my variable speed drill as a starter.

Brian Rupnow · « **Reply #141 on:** September 17, 2014, 05:46:41 PM »

So now the engine has a starter ring. If I ever get finished to the point where I want to start it, the ring will be waiting for me.---On to more interesting things like pistons tomorrow. (I hope!!)

Brian Rupnow · « **Reply #142 on:** September 19, 2014, 05:59:43 PM »

Somebody messed up, and my gasket material never got ordered. Now it's ordered and won't be here until Monday or Tuesday. This doesn't cause a huge problem, because I'm up to my armpits in "real" work right now and have no time to play machinist. This drawing is an interesting part. I have made it before. It mounts a set of my favorite Chrysler product ignition points, and clamps onto the extended head of a crankshaft support bushing. By loosening off the clamp bolt, I can manually adjust the ignition timing while the engine is running. This is no big thing once the engine is all set up and running at its optimum timing, but it sure is a nice thing to have when first starting the engine and "setting up". I used this when I built the Odds and Ends hit and miss engine designed by Philip Duclos, and it really is a handy thing to have on the engine.

Brian Rupnow · « **Reply #143 on:** September 19, 2014, 06:16:37 PM »

Now I have enough work to keep me going until the gasket material arrives. There is a big chain of consequence attached to the lack of gasket material. I can not permanently attach what I have been calling the "combustion chamber" to the cast iron cylinder until I have a ring of gasket material to insert between them to prevent loss of compression. I can't hone nor lap the cylinder/combustion chamber until they are permanently attached to each other. I can't make the piston until I am finished the lapping and honing. I'm sure there will be enough work in this con rod and the points mounting bracket to keep me going until the gasket arrives next week.

Brian Rupnow · « **Reply #144 on:** September 19, 2014, 08:02:30 PM »

Here we have the con-rod layout. I don't work to the layout lines, but they let me know if I have turned the dials on my mill one too many times when I am actually machining it. I don't trust my mill vice to hold this perfectly flat while working on it. I will put a sacrificial plate underneath it and use hold down bolts in the tee slots to hold it flat on my mill table while drilling and boring all the holes. Two critical holes for the bearings at each end which will have to be bored, and 4 drilled holes to form the radii where the straight sides blend into the round ends.

Brian Rupnow · « **Reply #145 on:** September 20, 2014, 08:30:53 PM »

That went well!! The machining was pretty straightforward stuff. I did learn one new thing today. When you order this type of bearing, the outer diameter comes in at .0005" to .001" oversize so that they can be pressed into a hole made by a standard reamer. For 49 years now I have been putting a note on machining drawings "Bore for light press fit of .562" nominal o.d. bearing (or bushing).--I never actually realized that there wasn't some magic formulae or set of undersized reamers involved to do this. As you can see in the picture, the 1/4"small end bearing is sealed with rubber seal lips. I was unable to buy a sealed 3/8" i.d. needle bearing----anywhere, for the big end. I guess this means that I will be running some oil in the crankcase after all.

Brian Rupnow · « **Reply #146 on:** September 21, 2014, 03:51:26 PM »

By Golly, Miss Molly---I must be doing something right!!! Along with all the other things I had to do this weekend, I managed to carve out enough time to make the con rod AND the ignition points mounting block. I decided at the last minute not to put the raised boss on that is shown on the drawing. The head of the bushing it clamps to only extends 3/8" past the aluminum backplate, so that is the thickness I finished the points mounting block at. I used a scrap of bronze, just to balance the bronze flywheel aesthetically. The points mount up perfectly, and all it need there now is an ignition cam to finish that bit off. The #5 capscrew sticking out horizontally is where the handle will screw into, to adjust the timing.

Brian Rupnow · « **Reply #147 on:** September 21, 2014, 06:36:53 PM »

Time for one last "Quicky" before I shut down for the day. The all important ignition cam. This cam serves a dual role in life. It opens/closes the ignition points, but also acts as a shaft collar to prevent any axial movement of the driven crankshaft in its bushings.

Brian Rupnow · « **Reply #148 on:** September 22, 2014, 07:37:13 AM »

The ignition cam is machined and installed. For any newbees following these posts, this kind of ignition cam holds the points open most of the time. They only close when the flat, which is about 3/8" long pass under the rubbing block on the ignition points. This gives enough time to charge the primary windings on the ignition coil, and when the points open again as the cam revolves, that is when the spark occurs.---Brian

Brian Rupnow · « **Reply #149 on:** September 23, 2014, 07:55:40 PM »

The cast iron cylinder and the aluminum valve body (which I have been mistakenly calling the combustion chamber) are now permanently and forever locked together with a ring of super duper heat resistant gasket material and some high temperature gasket goo.--That's not to say I couldn't take them apart, but I don't want to. I want to treat the two items as a single component now, hone them together, lap them together, and then make my piston to suit the bore.

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Author Topic: Side Valve i.c. engine from Bar stock (Read 174846 times)