Design and build side shaft hit and miss engine from bar stock

[Brian Rupnow]

Man, I'm livin' large today!!! Finished the face cam this morning, laid down for my old man's nap this afternoon, then got up and made the ignition cam. And just as I finished the ignition cam, goodwife showed up from her part time job at the library and took me out to eat at A & W. Life don't get much better than that!!!

[Brian Rupnow]

It's no fun having an ignition cam if you don't have the rest of the parts that go with it. Today I made the ignition points mounting block and adjusting handle. I keep an old set of Dodge ignition points that I use for "set up" purposes only. Everything fits in behind the flywheel, which has been removed for this picture. My original design of the points mounting block allowed for adjusting the timing while the engine was running. I realized that I couldn't use the same method for this engine, but I redesigned the mounting block and put in two slotted adjustment holes which can be easily accessed thru the holes in the flywheel web--just not while the engine is running.

[Brian Rupnow]

A really good sign this evening!!---I filled the water reservoir with water and nothing appears to be leaking. There are six bolts which break thru into the water reservoir, and they were all coated with clear silicone on the threads before they were installed. The sides from which the cylinder enters and the side where it exits were both sealed with viton O-rings and silicone when the cylinder was installed. I am going to make a very fancy polished top from brass to fit the top of the reservoir, and either Loctite or J.B. weld it into place, and I had to be sure I had no leaks before doing this. I will leave it full of water overnight and hope there are no puddles around the engine when I get up tomorrow.

[Brian Rupnow]

This morning I machined the valve cages from brass. These "cages" have a dual function. They guide the valve by way of the reamed center hole, and they also have the valve seat machined in them using a special tool after the Loctite has set up for 24 hours. They are machined to be very slightly larger than the 0.394" holes thru the cylinder head, and are pressed and loctited into the head. The inside of the holes in the head have been degreased using a q-tip and laquer thinners. No cutting oil was used when the valve cages were machined, so they don't need degreasing. Also in the picture, you will see a piece of cold rolled steel that I use for a "pusher" so that I don't deform the valve cages while pressing them into place in the cylinder head. There will be another hole thru the sides of these cages for the inlet and exhaust ports, but it will be drilled thru both cylinder head and valve guides after the Loctite has "set" for 24 hours.

[Brian Rupnow]

Both valve cages are now pressed into place. At the last minute I decided not to use my arbor press, and just used my bench vise to push the cages into place. The "pusher" didn't get used. The holes in the cylinder head were reamed to 0.394". The valve cages were turned to 0.395" except for the shoulder. I seem to be getting better at this "press fit" business. The recess you see in the top/outside of the valve cages is in there to keep the valve springs centered when they are assembled with the valve which passes thru this guide.

[Art K]

Brian,
Looks like you are making good progress. It's a good thing the sleeve and water jacket don't leak, I could picture that being a pain in the backside.
Art

[Brian Rupnow]

Yes Art, if the reservoir leaks there is a lot of heartbreak in store trying to disassemble everything and seal it up again. When I came down to my shop this morning, there were no puddles anywhere around the engine, which made me feel really good.---Brian

[Craig DeShong]

Look'in GREAT !!! 

[Brian Rupnow]

Today we are going to start the new year off with a valve tutorial. For all of you guys with years of experience, this will be kinda like teaching your grandma how to suck eggs. For all the new-bees following, this method has proven to be "tried and true" for me. There are two critical areas on a valve. The most critical is of course the valve face which seals against the seat in the valve cage. The second critical area is the shank of the valve itself. It must fit into a reamed hole in the valve cage, and "run true" without sticking or being sloppy. In the two attached pictures, you will see one short piece of scrap with a 0.125" hole drilled and reamed thru it. Why??--Because, as the valve is being turned down to be a "good sliding fit" in the valve cage, we need something with a very precise 0.125" diameter hole to
 keep checking the size of the shank we are turning on the valve. This is an area where I have been burned before by taking measurements with a micrometer and trusting them to give me a "good sliding fit". With the 0.125" reamed hole in the piece of scrap, I can exactly replicate the hole in the valve caged which was reamed with the same reamer. I do NOT recommend using the brass valve cage as a checking guide. I have damaged brass valve cages in the past by doing that. The second picture shows a piece of 1/2" cold rolled in the 3 jaw chuck, with a portion of it turnmed to 0.375". Why--because no 3 jaw chuck has 0 runout. my chuck has about .003" total indicated runout, and I want the head of the valve to be perfectly concentric with the shank. Doing it this way ensures concentricity between valve stem and valve head.

[Brian Rupnow]

When I make valves, I cut the valve seats in the valve cages to an included angle of 90 degrees with a special tool I will show in a later post. I like to make my valves with a 92 degrees included angle. This seems to work best for me when it comes to lapping the valves into their seats for an air tight seal.

[Jasonb]

That's a 92 degree included angle as you INCLUDE both angles from the central axis eg 46 +46

[Brian Rupnow]

In order to cut this angle, the topslide is swung around until the protractor is showing 46 degrees. This essentially means turning the top slide almost completely around and locking it in that position. Now with the lathe set up like this, it means I can reduce the shank to the correct diameter, and then use the topslide to cut the 46 degree angle without changing any set-ups.

[Brian Rupnow]

Now we are at the stage where deflection becomes the enemy. Whatever the length of your valve-stem is, divide it by 3 and that becomes the length which you machine. I am using a brand new HSS cutter here, and taking 0.010" depth of cut. My target diameter is 0.135" diameter. When I'm getting close to the finished diameter, I reduce my depth of cut to 0.005", and taking the same cut over two or three times, because at this diameter, the work will spring away from the tool. I am leaving the part 0.010" oversize for a reason.

[Brian Rupnow]

Now we get to the last third of the valve stem. Very much the same as the previous two steps, but when you get down to 0.135" diameter over the full length there is one more thing to do. we have left 0.010" oversize on the full length of the stem. Now you could work it down the rest of the way with 200 grit carborundum cloth, but it would take an awful lot of polishing. I prefer to back the cutting tool all the way out past the end of the valve stem and advance it .002", then take two or three cuts full length at that setting. Then advance it another .002" and take two or three full length cuts at that setting. Measure the portion of stem closest to the chuck, and you should be down to about 0.127". Don't measure out at the unsupported end, because it will have deflected away from the cutter and will give a false reading. And remember--measure very carefully. If we go below 0.125", we have ruined the part. Now is the time to very carefully start polishing with your carborundum paper--and remember--the part will be larger at the unsupported end than the other end. Work the part down and keep trying to slip your test piece with the reamed hole in it over the valve stem. This is a rather ticklish business, and best learned by experience. Just be sure to shut the lathe off and check frequently with your test piece. You don't want to end up with the stem undersize. once you have reached a point where your test piece will slide all the way, you are ready for the next step.

[Brian Rupnow]

Once you have worked the stem down with carborundum paper or emery cloth (This always takes far longer than I thought it would) to a point where your test piece slides all the way up to the end of the stem, you are ready for the next step. (Note that I didn't say the LAST step). Since we already have the topslide set over at the angle we want to cut, we take light machining cuts until we have formed the angled face of the valve. Be careful not to undercut the stem while you are doing this. I would love to say that my valve faces always come out perfectly smooth with a mirror finish,but they don't. That will be taken care of when we are ready to lap the valve into the seat. Do NOT part the valve off from the parent stock at this time. Take it out of the lathe and leave two or three inches of unturned stock to act as a handle while lapping the valve into the valve guide.