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David Kerzel,     Pompano Beach, Florida

Simple 4 cycle vertical, 0.700 bore X 0.700 Stroke

Two years a go I built a series of 3 vertical engines with 1.000 Bore and 1.000 stroke.  The plan was to get a good design and reduce the bore and stroke.  I got distracted but have come back.  This engine has been on my CAD for a year and incorporates what I liked and disliked form the last 3 engines.  I will write more later about each of the previous verticals and what I like and dislike.

I have been working in Solid Works 3D cad for about 2 years.  The last 2 verticals were mostly SolidWorks but this one is 10% Solid Works.  In 3D cad the parts can be mated and checked in detail beyond regular drafting.


I got some rough cut aluminum at work.


The first few hours were spent squaring up and getting the material to size. The basic mounting holes were added.


After a great weekend spent in the shop.  The main crankcase is starting to take shape and is ready to accept the cast iron cylinder liner.  Its been a while since I turned metal ad some tools need replacing. New tools need to get ordered after reading a years worth of building articles and the ideas and better practices that have been discussed. 

As the size of the engine decreases attention to detail becomes more important.



Timing cam, gear and bearing holder

I decided on a 3 part silver soldered crank.



I have been poking at parts since Thanksgiving.  I have decided my 3 in 1 lathe mill does not have the accuracy  need and I have been moving parts to the Sherline for the finishing cuts.  Roundness is better but finishes are better with power feed.

The crank is silver soldered and needs clean up

valve cages. I am going to try to bore the bearing as described in Model Engine Builder Magazine and see if I can get valves to work on the first try.

Blanks to cut the timing gears.  The mandrel used to hold the gear cutters screw stripped and is locked on a slitting saw.  Several other tools seem to have worn out since I last used them.  I ordered some new ones and hope to continue this next weekend.



I finally got the arbor and started cutting the timing gear.  Two teeth after this photo the chuck came loose and the part was grabbed by the cutter, instant junk.  So next week I will try again.



A much better day cutting gears.  I moved back to the larger chuck I had always used before and everything was solid.
Next will be the cam.  I plan to cut the 2 lobes and the shaft as 1 part.  I have always soldered or pinned lobes to a shaft so it will be new but I think it will be simple with this same rotary table set up.


I spent the day making the dual cam and the fixture.  I had planned to mill the cam like I did in the last engine but my notes preferred the turned cams smother surfaces.  It was one of those days, the steel turned like brass perfect finishes, dead on for every dimension.  well when I took the beautiful part off the fixture the lobes were less than the planed 90 degrees.  The turned out to be 10 degrees short, think it is the 5 degrees of full open on the cam times two.


I made 3 new cam blanks for the basic cam that have valves closed at TDC and BDC. A version discussed on the message board with exhaust opening 20 degrees (crank) before BDC exhaust remaining open for 8 degrees after TDC and intake opening 8 degrees (crank) before TDC intake remaining open for 20 degrees after TDC.  I also plane for one in the middle.

As I worked on the drawing I needed to optimize the radius and a new fixture was needed.  I made protractor like dials for each cam.  The green area gets cut in both lobes, The red only areas cuts the outer lobe and the blue only cuts the inner lobe.  To cut the inner lobe I used the parting tool as the cutter.

I was very careful on cam1, Cam 2 I just dialed in the color coded numbers,  I did it again for cam 3 but the color codes were revered so the lobe phase is wrong.

I ended up with the two extremes of cam design.  You can see the wider full lift area and the wider lobe separation on the cam on the left.  I made a extra timing gear and pressed it all together.  It took a while to figure out how to get the lobes aligned with a tooth.



For the last 2 weekends I have been working on the connecting rods.  These ended up being milled.  Sintered bronze big end and brass small end bearing

The crank shaft, bearings. spacers, all together.  The bearing housing needed a slight change because the big timing gear teeth had no clearance.  Some how I lost a cam shaft bearing so I cant fit it yet.



He parts are piling up.


I finished the valve cage parts and the valve parts.  I could find no silver solder flux.

In Model Engine Builder Magazine a few issues back I read where the valve guides should be bored.  Just drilling might not be true or round.  I pressed the guides in the cages and got a carbide boring bar that needed a new holder.   On the first cut it was obvious my guides were not straight and smaller at one end.

the weather is getting too hot and humid to work in the yard so back to this engine.

The project stopped when I could not find the silver solder flux 5 weeks ago.  The new flux has been on the desk almost that long.  Today I got back to it and soldered the valves.  I leave the heads about .010 oversize so A few light cuts will true them up.  The Sherline chuck seems to have problems with hex stock and small smooth hard rods.  The chuck spun open as I was cutting the seat angle and I ended up with an excellent bent nail.  So I made a few new parts and got a second valve made and the assemblies but together.  Those bored bearings  have just the slightest drag along the valve stems length.


I have not had any shop time for weeks.  I figures out where the project was and found the tools I ordered and made the rocker arms.  Those huge nuts are 1/4 hex, I will have to make some smaller brass ones.

I saw a Crestmobile car in a museum in Savannah and I like the Crest engine.  I think it will be the parts form this engine in a fancy crank case and be a 1/3 scale model.  Link to the Crest project




Finally some time to work on this.

I was so glad all the parts and tools were in a small plastic box.

I changed the fin direction on the head to be inline with the crankshaft.  I added the holes for a hall sensor and finally got the push rods in the correct position on the 3D drawing.







I machined the holes and fins on the head. 

I went to press in the valve cages and they went in in too easy.  More than finger force but not much.  The valve cages are the best I have ever made and the head is dead on as well.  I need to pick which one should get remade.  I do not believe LokTite would work with dissimilar metals in a hot area like the head.













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