Vertical Cylinder I.C. Rupnow engine

[Brian Rupnow]

-I lay in bed last night thinking about that cylinder head, and it's going to be a real toad-sucker!!! Before I thrust something on you guys that isn't do-able, I think I better build it myself to make sure it can be machined. Today will be cylinder head day, with "step by step' in process pictures.

[Brian Rupnow]

I rooted around in my bin until I found a chunk of 2' aluminum that was "just long enough" and chucked it up in my 3 jaw. Then I faced it, turned the 1" projection on the nose of it, and cut the single groove specified on the drawing. there is about .003" tir on my lathe, so I turned a "skim" off the o.d. of the piece to get everything nice and round.

[Steamer5]

Hi Brian,

   at the ready!

Cheers Kerrin

[Brian Rupnow]

Okay--this is the end of "conventional' machining on the cylinder head. First step was to set it up in the rotary table chuck and center it under the quill. The "parallels" are simply spacers so that when I drill thru I don't hit the hardened chuck jaws with my drill. First order of operation was to put in the slot that the nose of the sparkplug extends into. After having done that, now the cylinder head has taken on "rotational characteristics' which simply means that any bolt holes put in after that have to be a certain distance in X and Y coordinates from the slot. Since there will be no way to see the slot once the cylinder head is flipped over for more operations, I won't be able to see the slot, so I put the thru holes in now while I'm in the same set-up. I will use the holes to align things when I flip the cylinder head over. I will also put the counter-bores in when it is flipped.

[Brian Rupnow]

Hi Brian,

   at the ready!

Cheers Kerrin

Hi Kerrin--Glad you tuned in!!---Brian

[Brian Rupnow]

 I went in to tear down that last set-up, and fortunately I took a look at the drawing first and realized that I had to put in the bores and counterbores for the valve cages while still in that same set-up.  Lucky I looked at the drawing!!!

[cfellows]

Brian, I find this design to be quite elegant.  It's simple yet all the parts are very functional.  I really like the looks of it.  Of course, I've always been a big fan of open frame engines.  I like to have access to all the parts and I enjoy seeing them move when it's running. 

Your engine also looks like it would scale down (or up) nicely.  This may sound trivial, but I've found that I like engines with a 7/8" bore.  They seem to be a little more manageable than their 1" bore counterparts.

Don't know if I have another IC engine build in me or not, but you've got me thinking about one...

Chuck 

[Brian Rupnow]

Here I have flipped the cylinder head over in the chuck on the rotary table, centered it under the quill,  put a .170 dia. drill in the spindle chuck, offset the table 0.760" in the Y axis, then rotated the rotary table until the .0.170 drill will pass freely thru the existing hole. Now I have things located. Then I put a counterbore in the quill chuck and counterbore three of the holes to a depth of 0.164". The two remaining holes, which will end up in the slanted surface of the cyl. head get counterbored  0.476" deep. I have to drill and tap the two #6-32 holes that hold the rocker arm bracket, then the next step is where things start to get hinky.

[Brian Rupnow]

Chuck, You know I would LOVE to have you on board. If you reduce the bore size to 7/8", you will have to do some serious rearranging of the head, because there just isn't enough room to fit everything when using an M10 thread sparkplug. You might have to round the corners on the rod too, so it doesn't hit the bottom of the cylinder bore as the crankshaft rotates.--As a side note--I find that the larger my cylinder bore is, the less trouble I have getting my engines to run well and slowly.

[cfellows]

Yeah, the 7/8" bore with overhead valves pretty much requires scaling down to a 1/4" x 32 TPI spark plug, but I don't find the extra expense to be too burdensome.  And, you're right that as the bore is reduced it gets harder and harder to make the engine run evenly and slowly.  For that reason, I won't normally consider anything smaller than 7/8".

Chuck

[Brian Rupnow]

Okay--I promised you "Hinky"---we got "Hinky"!!! when I finished that very first step in the lathe, I had parted the cylinder head off from the parent stock to exact finished length. I dug around in my scrap bin until I found a short piece of 2" x 3/4" bar and mounted it in my vice. I drilled a shallow 1" clearance hole and drilled/tapped 3 holes that corresponded with the 3 head bolts which were not on the sloping surface. I bolted the head to the bar, and tilted my vice the required number of degrees to finish the sloping face and put in the sparkplug hole and counterbore. Don't worry if you don't have a tilting vice like mine---Just set it up  at 90 degrees to what I did so you can tilt it up the required number of degrees in a fixed base vice. So--the head is finished. I'm sure it is the hardest part of this engine. If I can do it, so can you.

[Art K]

Brian,
I find your builds fascinating so I will be following along as well.
Art

[Brian Rupnow]

Hi Art--Glad to have you along. I didn't really plan on starting to build this until fall, but winter is just starting in Australia and some of the boys over there are looking for project work right now. Anything that looks a bit fishy like this engines cylinder head, I want to be sure that it can actually be built before I lead someone down the garden path.---Brian

[Brian Rupnow]

I ordered a set of Tecumseh points and condenser at Ideal Supply, and they will be in tomorrow. Also, looking at the solid model of this engine, I see a perfect set up for a small cooling fan driven by a friction wheel which is turned by the flywheel.

[Brian Rupnow]

More fiddly bits---and yes, I know--I spelled vertical wrong.--so shoot me!!!