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David Kerzel, Pompano Beach, Florida david@FloridaAME.org
Simple 4 cycle vertical, 1.00 bore X 1.00 Stroke, Build 2
Last year I built the first in this series of engines. The first one (click here to see it) was designed for construction on a lathe and drill press only. This is a refined design that needs a lathe and mil for construction. I think I removed all extra material and am covering the cylinder with fins for more cooling. There are two versions of this engine, flat head and overhead valve. Since the original was flat head this will be overhead valve.
This engine design is intended to morph into other engines so I will be simultaneously building a 2 cylinder V version. I am going to build them as best I can from my drawings and notes.
A new carburetor, simple barrel design, but with the largest fuel ports and jets I have ever made, 5/64. The first tests ran good but the needle was all the way out in the OS carburetor. This one has similar barrel and the fuel ports are 40% larger. The propane I use is apart of the need for larger ports.
Last weekend I put the end plates on the crankcase and filled it with 1 ounce of oil. Oil comes flying out the push rod holes, what a mess.
Then I put the valve cover on. I had not put the vent check valve in. In about 30 seconds the shop was full of smoke and I was driven out.
I added the vent check valve to crate a negative crankcase pressure. No more exhaust smoke but a fine mist of it sprayed out the vent, then it suddenly stopped.
I ran it for a bout 40 minutes at low and high speeds.
This is the most responsive engine I have built.
It was getting late, so I took it in and drained the oil.
Finally all the parts are done, it has been about 5 months since the first metal was cut.
After putting it all together the compression seemed weak. I made a fitting to fill the cylinder with compressed air. Air rushed out the bottom of the cylinder.
I opened it up and the rings had a few burnish makes on a few points. Holding the cylinder up to the light with the ring inserted I could see the rings were not true round. with a casual look the looked perfect but they are wavy.
I had made 6 sets of rings and started checking them. I found rings for 2 sets that appeared good or only had the slightest imperfection. I also had spare cylinder liners so I used one to lap the ring outer diameter. About 10 stokes with 400 grit lapping compound made a uniform finish on the outside diameter. A final 2 strokes with 1200 grit to get a polished look.
I got compression. I did the air test and there were no audible leaks, valves perfect, rings now sealed.
I hooked up the ignition and propane for fuel with a OS carburetor.
A spin with a drill, suction on the carburetor, pressure at the exhaust, sparks from the top of the spark plug to the head. I assumed these 1/4 inch long sparks were caused by a oil fouled plug. It was clean. I know that compression increases the voltage needed for the park but this seemed like too much. I put a plastic strip around the spark plug, gave it a spin and it started.
I didn't let it run for more than few seconds since the crank case is still open and the engine only has a squirt of oil in it. It responds well to throttle changes. This is the first time one of my engines ran the same day it was assembled.
VIDEO Starting up day 1 (Windows media file).
Another long weekend but not much shop time.
I got the piston and rings fitted and moving good in the cylinder. Valve assemblies were pressed in and finished off.
I have started a secondary project of an ignition coil. Click here to go to that project.
It has been 5 weeks since I spent time in the shop. Family reunion and fishing in Oregon and a lot of catching up at work.
I silver soldered the valves together and made the fishing cuts. A quick lapp with diamond goop followed by Clover 400. The valve assemblies and cylinder liner were pressed into position. Cooling fins were cut into the top half of the engine. Now its time to get parts moving and check valves for leakage.
I started making the valve parts. Silver solder and a light cut to true up the valves is next.
I was working on one of the last drawings and started sketching a alternate design for the V spin off. The plan had been have the cam shaft between the cylinders. now I am thinking the push rods should be between the cylinder and the flywheel. It makes the engine smaller and allows larger cooling fins. Now should I just jump to the 2 cylinder version or make a 1 cylinder version first?
I got most of the machining done on the head, valve cover and cylinder cover. The crank shaft and cam shaft have been fitted.
Cam parts are finished.
The blocks for the cylinder, head, and valve cover are turned to size.
I tried to use a adjustable reamer to true up and remove .002 from
the main bearings. I now understand why adjustable reamers don't
seem to have a big following.
The crankcase main parts are nearly done.
As I continue to work with the 3D CAD I have decided to change this to a overhead valve design.
The 2 cylinder V design will remain flat head. There are issues with crank case oil mist draining that I cant resolve in the V design.
I split the rings, heat treated them and added the holes in the oil control rings. I started the parts for the crankcase.
I make my pistons from square aluminum. It makes it easier to mill out the inside and get the wrist pin perpendicular
I made a expanding mandrel that uses a 1/8 pipe fitting to expand it to hold the raw cut rings while I face them to the exact thickness. This is so much easier that sanding them to the proper thickness.
I have continued with my 3D CAD. I have only found a few missing dimensions and machining descriptions. Doing the 3D has a thought process like making the part. I am not sure this package is the one so I will try another one.
Rings are cast iron. I am making 2 full sets.
Cylinder liners got lapped. I tried diamond lapping compound 240 grit. It cut a lot faster than Clover carbide lapping compound and continues to cut. The final finish is not as smooth a Clover so I did the final few strokes with Clover to get the finish I wanted. Then I started making the cast iron tube to part the ring from.
I have been working on the 3D drawings for the engine, it is interesting and showing me a lot of missed details.
Cylinder liners were roughed out of 1 1/4 cast Iron bars. Lots of gritty chips everywhere, machine, hair. ears, living room...
I am evaluating 3D CAD for work and using parts from this engine in
Split big end bearings. The brass is soldered together and turned on the solder center line
Making connecting rods. I tried to turn the taper but I could not support the small end and even with 0.002 cuts the tool grabbed, jammed the part under the cutter and pulled it out of the chuck. I ended up cutting a series of steps and filing the taper in.
This engine has lots of options, 1 or 2 fly wheels.
The crank shaft is made from solid stock. The taper for the fly wheel is cut when the fly wheel is cut to get exact matching angles.
Copyright 2007, Florida Association of Model Engineers and engine builder as noted above, All rights reserved.