Rockerblock I.C.--Something a little different-

[Ian S C]

I'm a bit worried about milling with the Jacobs Chuck, even on little jobs it can drop out if it's on a MT, and if it does not have a draw bar.
That hopper came up well, like others I might have looked at some cheaper way, but I think that the way you did it was in the long run the most economical, and the most pleasing to look at.
Ian S C

[Brian Rupnow]

Jim--My mill is a CX601 from BusyBee.

[Brian Rupnow]

Ian--about the only time I put an endmill in a dedicated holder is for heavy milling on steel. For brass and aluminum it works just fine in the chuck. I have been told numerous times by numerous people how bad this practice is, but it's a pain in the arse changing back and forth between the chuck and dedicated holders all the time. I have never had a cutter come lose or cause a problem doing it this way.---Brian

[Brian Rupnow]

This mornings labours were limited to "Things I can make in the 3 jaw chuck." I wanted to make the muffler from brass, but decided to make it from aluminum, because of the weight savings. The weight wouldn't matter if it screwed straight into the cylinder head, but it doesn't. It screws into a 90 degree elbow which is screwed into the cylinder head, and I am afraid that the weight of a brass muffler would make the 90 degree elbow turn and hang down at some lop-sided angle. I chased down a very short stub of 660 bronze which was left over from something and made the top rocker pin and retainer, as well as the bottom rocker pin from the bronze. I am running out of things to build that will keep me away from the valve train. The ignition cam is made and installed, so all I have really left to do is make up the two 90 degree brass elbows and the oil cup.

[Brian Rupnow]

As often happens, when I first design something from scratch, if I don't have a  clear vision of what is involved in making a part, my imagination runs a bit wild. Then as I work my way thru the build, reality sets in. Such is the case with the cylinder oiler. It started life as a somewhat fanciful "add-on" oil reservoir. Although I could actually build it as "first designed", there is really no provision for keeping it in place on the cylinder. if I used any kind of Loctite to "glue" it in place, then I would never be able to remove the waterjacket if I had to, because of the small tube at the bottom of the oiler that fits into a hole on the top of the cylinder. So--Today I redesigned it as a "bolt on" It can be attached to the front of the waterjacket with two #4 s.s. bolts. I have a length of 1/16" o.d. x 1/32" i.d brass tubing that I bought a few years ago for a carburetor experiment. I will Loctite this tube into a hole in the redesigned oil cup. With this change, it both simplifies the machining of the oil cup, and it is also removeable by removing the two #4 bolts and lifting it straight up away from the cylinder.

[Brian Rupnow]

So---I've got a running start on the two 90 degree elbows for the exhaust/induction. These elbows will be made up from two pieces silver soldered together. That's not a lot of machining, but its all I'm good for today.

[Art K]

Brian just wanted to let you know I'm still following along.

In a situation like this, all you can do is machine everything as closely as possible to the drawing, and have faith in the designer.

Especially when you are the designer! Everything is looking great.
Art

[Brian Rupnow]

Either I'm getting better at silver soldering, or I'm getting luckier--not sure which. The elbows are both finished and I'm very pleased with how they turned out.---Brian

[Brian Rupnow]

Nothing much really accomplished today, as I spent the day working in a factory across town designing spinforming lathes. However--When I got home this afternoon I did one bit of machining that is a bit interesting. I have decided that both of the 90 degree elbows that thread into the cylinder head are going to need locknuts to keep them from "drooping" due to the weight of the carburetor and exhaust. The external threads on both elbows is 5/16" diameter, but a regular 5/16" nut (as seen setting between the two elbows) looked to big and clunky.--So, I took a pair of 1/4" hex nuts, ran a 1/4" drill thru them, and tapped them out to 5/15" u.n.c. Then I set them up in the lathe, and thinned them down to 0.150" thick. The result is a size more pleasing to the eye, and will require a smaller "spot face" on the side of the cylinder where they screw into.

[Brian Rupnow]

Tonight we have an oil cup. Granted, it won't hold much more than a teaspoon full of oil, but I don't plan on doing any long haul trucking with this engine. The only reason I'm putting an oil cup on at all is that I hope to power this engine with propane. If I used my normal gas/oil mix, it wouldn't even need an oil cup. The oil-cup is just setting in place right now, without the 1/16" o.d. x 1/32" i.d. tube Loctited into it. I will wait until I have tapped the waterjacket and bolted it into place before I drill the oil hole in the top of the cylinder and Loctite the tube into the oil cup.

[Brian Rupnow]

This next part is going to be--Ahhh--interesting. It is one of those multi purpose items that does 2 or 3 jobs. First and foremost, it provides a set of guides for the lifters to ride in. It also provides a place for the rocker arms to pivot. It acts as a "bolster" to lend some strength to the cylinder head plate which has a large "window" carved into it to access the cams which operate the valves. It could have been built from aluminum with bronze lifter guides pressed into place, but I opted for bronze because it adds some contrast to the mostly aluminum engine, and doesn't need any inserts in it for lifter guides.

[Brian Rupnow]

I am constantly amazed by the amount of time required to make some of this stuff. I'm not slow at machining. Its just that there are so many steps and set-ups to make a simple part like this. I've just put in a complete 8 hour day making this lifter guide/bolster. It has turned out fine. I decided to make the rocker arm tower out of a separate piece, which will be bolted on. I will make it tomorrow.---Brian

[Brian Rupnow]

This picture shows the finished bolster/lifter guide/rocker arm pivot finished and in place on the engine. The two open holes directly below the rocker pivot tower are where the valve lifters set. The camshaft and (as yet unfinished) cams set directly behind those two holes. (See picture without bolster in place.) The open slots on both sides allow me to get a hex wrench in there to lock the cams to the camshaft in the correct rotational aspect. The two open holes in the "cylinder head" are where the valves will be.

[Brian Rupnow]

This has been a somewhat  hither-thither morning. I made and installed two brass valve cages, dealt with a roofing contractor, and helped good wife sort out a ton of stuff in my garage as she prepares for a Parkinsons Charity yard-sale. The diameter of the valve cages are such that they can't be pressed into place with fingers alone, but slide in very smoothly when coated with #638 Loctite and pressed in with my 1 ton arbor press. I have sorted thru my box of springs and found the spring that will keep my valves in the closed position. The slight recess in the top of the valve cages contains the bottom 0.050" of spring so that it can't slide over and rub on the valves when they are installed. The picture showing the inside of the cylinder head shows up a lot of dirt that I didn't even know was there. The Macro setting on my camera sometimes does that. If I'm not interrupted in the next couple of hours, I may even have some valves made today.

[cfellows]

Coming along nicely.  Let's hope you don't run into any problems getting the valves to seal.  That's pretty much been the bane of all my IC engine builds.

Chuck