The

"McVickerish" Engine

Page Four

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In this installment, we will convert the basic engine to a different form of exhaust valve actuation in order to make the engine more reliable.

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Click on the picture to view in high resolution.

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24 August 2010:

Now that I've decided that the McVicker design has some serious flaws, I've decided to modify the engine but keep the name I've given it because it will still be gearless and camless.

 

I need to make some sketches to see if it will work but, I've got a large 12 volt DC solenoid that I think may have enough force to open the exhaust valve.  That, in addition to some more electronics should at least prove to be an interesting experiment.

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27 August 2010:

Well, after sitting and staring at it for a while, I think I know how I'm gonna do the solenoid conversion.

Solenoid laying there for ideas.

What I plan to do is to use a hunk of 2" X 2" X 0.190" steel angle iron for the mount.  It will also serve to block off both of the valve cylinder ports which won't be used in this iteration.  If the solenoid proves a bit too wimpy to open the valve when the engine is running, I may exhaust the port that is uncovered by the head of the piston in order to relieve some of the overpressure to aid in opening the valve.

Drawing of the solenoid conversion.

 

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2 September 2010:

I got some parts made in the last few days.

   

Solenoid plunger with push-back spring and plunger.                                                  Solenoid with plunger.                           

Since I don't know exactly how hard the solenoid can push against the rocker arm, I gave the plunger more than enough room to move  In order to keep the plunger from hammering, I've made a little brass plunger with a relatively weak spring that will keep the valve lash to zero no matter how the rocker bolt is adjusted.  

 

In the worst case if the solenoid isn't strong enough to open the valve against overpressure, I may want to allow the plunger to go all the way back so it can get some speed up before striking the end of the rocker bolt.  In that case, there would be a really pronounced click when the valve opens.

 

I made the solenoid bracket out of a piece of angle iron that I've milled to be a reasonably accurate 90 degrees on all surfaces.  

 

Because I think I'll need to have the overpressure relieved in order to minimize the opening force on the exhaust valve, I'll use the already drilled exhaust port.  It's not very big but will at least relieve some of the pressure to open the valve.  For this use, I'll route both ports to the exhaust because it's probably not good to leave the ports blocked.  If blocked, they will accumulate all kinds of nasty stuff.  With the ports open to the exhaust, at least the crud will be blown out. 

  

Solenoid bracket, spacer and blocking plate.                                                  Blocking plate in position.                                          

As you can see in the drawing from 27 August, there is a spacer plate between the solenoid flange and the mounting bracket.  This allows the plunger to move back about 0.3", which is more than enough to allow for adjustments for valve opening.  I figure that about 0.150" of opening should be adequate.  I've also slotted the bracket to allow for vertical adjustment of the solenoid to align it with the rocker bolt.

 

Speaking of the rocker bolt, I've decided that, for alignment reasons and the weight of the moving parts, I will make a new rocker bolt that has a slightly spherical shaped face.  That face will match-up with a slightly spherical shaped face on the end piece which will be threaded on the rocker end of the pushrod.  It should work fine (says here in the fine print).

 

As you can see in the above left photo, I've milled slots to allow both of the ports in the cylinder to be routed to where I can connect a length of copper tubing to route the flow to the engine exhaust pipe.  Between the engine and the bracket, there is a plate that seals off the top of the passageway.  The photo on the right shows the top blocking plate in position.  Note that the top blocking plate uses the bracket mounting bolts underneath the cylinder plus it has two additional 6-32 clearance holes for holding it tight to the bracket where it is not squeezed between the bracket and the cylinder.

 

The bottom plate will be held in place by three 6-32 machine screws threaded into the bracket.  I don't use the four bracket mounting bolts on the bottom blocking plate because I don't want to space the bolts any farther away from the bracket than necessary due to clearance issues with the solenoid.  The bottom plate will be held by three 6-32 screws threaded into the bracket.  The single screw beneath the cylinder will be short enough to not extend through the bracket.  The two screws on the outside edge will be long enough to go through the top blocking plate.  Nuts and washers will be used to hold the top blocking plate to the bracket at the outside end. 

 

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9 October 2010:

Well, I finally got back to the project.  Today I got the solenoid mount and exhaust port parts made and put them on the engine.

   

Showing Exhaust Port                                                    Mixer Side                                                             Mixer Side 2

I made a large diameter spherical (convex) end for the pushrod that matches with a similarly spherical (concave) surface on the rocker bolt.

 

Initial tests seem to indicate that the solenoid is capable of opening the valve about 1/4 inch which is fine for this engine.

 

Tomorrow I'll start on the circuitry to control the solenoid.  It looks like I can do it with one dual one-shot (MC14538) and one dual D-type flip-flop (MC14013) integrated circuit.  The plan is to divide the spark sensor signal by two (one flip-flop) so I can have spark when the valve does not open and no spark when it does.  The same flip flop will determine when the exhaust valve opens.

 

One of the one-shots will be to set the dwell of the ignition (about 2 milliseconds) and the other will act as the governor to inhibit spark and hold the exhaust valve open when the engine is above the set speed.

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13 October 2010:

I've been futzing (That's a technical term) with the logic circuit to operate the ignition and exhaust valve solenoid.  So far, it's acting kind of hinky and I think that the few 14538's I had in my stock are bad because they don't time properly.  More are on order.

Working with the rat's nest.

One of the problems with projects like this is the fact that you have a couple of heavy loads switched by the logic using MOSFETs.  Especially with the ignition coil, which is only a couple of Ohms, the current is substantial and when it's turned on and back off (1.2 milliseconds), there is a glitch generated in the ground path that confuses the logic circuits.

 

As I've found from years of experience, all you can do is move grounds and supply lines around and bypass the heck out of the supply lines.  Given enough fiddling, futzing and tweaking, it will work.  This follows the old rule, "Once you've figgered-out what you're a-doin', you're done.".

 

I really want to see how the engine runs with this set-up but there's no sense in trying before all the glitches are worked out.

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1 November 2010:

Yup, it's been a while since I've done anything of note.  In the interim, I dug a big ditch in the front yard and did some painting and caulking.  What fun!

 

I did make some modifications to the circuit so the governor would work right.

Here's the schematic as it is now.  I may have to shunt R4 and R6 because I think they are causing the valve actuation to only work at slow speeds. 

 

Here's the circuitry as of today.

I hooked it all up on the engine and, after a few cranks, it tried to run.  As I said above, the exhaust valve quits working when the RPM goes above about 300.  If I set the governor to below 300 (about as slow as it will run now), it "latches-up" as planned.

 

If I have time tomorrow, I'll shunt the resistors and try it again.

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4 November 2010:

For the last three days, I've fiddled with the engine with only slight improvement.  First, I suspected something wrong in the logic for the exhaust valve solenoid.  To make sure, I put an LED across the solenoid coil and found out that the logic is working just fine.  The problem is that the solenoid is not strong enough to open the exhaust valve on the exhaust stroke following combustion.  It will open the valve after another stroke.  That makes for odd running.

 

I've tried several configurations of the solenoid but it still refuses to lift the valve on the first exhaust stroke.

 

I'm going to see if it's possible to force the valve to lift by using 24 volts on the solenoid.  This means getting into the circuitry and temporarily adding a second battery.  If that works, I may have to change to something like a starter solenoid.  

 

This engine is mounted on the 2009 Algore Edition Hybrid Green Hoyt-Clagwell and I don't like the idea of having a second battery on the tractor although, if I could score a small 24 volt alternator, it would be feasable.  After all, it does have a 24 volt propulsion motor.

 

Of course, if all else fails, I could change it over to something like a gearless Olds.

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6 November 2010:

The last few times I ran the engine, I noticed a periodic knock (it came and went) and decided today to figure out where it was coming from.  I found that the crankshaft had worked loose against the bores of the main bearings.

     

Points of looseness at main bearing bores on crankshaft.

It looks like I've learned another lesson from "The School of Hard Knocks".  NOW, I know I should have used bearing set Loktite at these points so the shaft couldn't work against the hard races of the bearings.

 

I didn't mic it but I decided that the shaft is too far gone to repair.  I'm ordering another length of ground and polished shafting to replace it with.

  

Removed crankshaft.  Note the galling from press fit.

When I used my Chinese "10 Ton Hydraulic Press" to push out the shaft, I wasn't sure it had the Moxie to do the job.  While pushing on the shaft, I learned something else.  The Chinese press cannot develop full force except at the very start of the stroke of the cylinder.  Otherwise, it leaks down faster than I can work the pump handle.  I think the bore swells under high pressure so, since the top end of the bore is stronger than the middle, that part of it must be used for full pressure pushing.  It did take pressure close to the red zone to get the shaft to move and it did so with a bang.

 

When the machine shop pressed the shaft into the crank cheek, they used a 50-ton press and it was straining at the end of the push and they said it was a really tight fit so I wasn't sure that my press could do the job.  It did.  Barely.  Note the galling of the shaft from the pressing.

 

Yesterday, while doing "honeydo" projects, I thought about the valve actuation on the engine.  Since I need the engine to produce ample power to run the alternator on the tractor and I want it to be easily started and more or less reliable, I've decided to dream-up some kind of positive valve actuator and use the solid-state circuit to drive the "governor pawl" to latch it up at governor speed.

 

I'm still thinking gearless but have to cogitate on how I'm going to get the valve to operate at every other stroke.

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8 November 2010:

I did some thinking on the problem and here's how I think I'm going to solve it.  I'll use 1/4" pitch single row roller chain with a 2:1 sprocket ratio to drive the cam and ignition magnet.

 

The head can be rotated 90 degrees so the pushrod will be inline with the crankshaft as shown below.

Engine with head rotated 90 degrees for valve action by cam.

I removed the elbow from the mixer (on the bottom).  I may have an issue with fuel flooding because the jet looks like it's about the same height as the tank.  The solution to this is to just not fill the tank all the way.

 

The exhaust will be run through a couple of 90 degree E.M.T. elbows and then down to the flex pipe to the muffler.

 

I'll still use the ported exhaust (since it's there anyway) and route it to the vertical section of the exhaust pipe.

 

Now, on to CAD to start on the parts to do this.

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13 November 2010:

Well - since our last thrilling episode, I've gotten the design of the hit & miss mechanism worked out and have started making parts.

 

               Engine frame flycut.                                                   New crankshaft with sprockets and camshaft.

After pricing spur gears, the plan evolved into using a #25 (1/4" pitch) roller chain and 2:1 sprocket set.  The cam is the original and superceded exhaust cam for The Homebrew Hvid engine which ended up in the junque box.  It gives a lift of 0.188" which is more than sufficient for this engine.  

 

Here's the camshaft assembly.

The cam bearings are from some deceased machine I parted out.  The sprockets are new purchased items.

 

The camshaft frame, machined out of 1/2" hot rolled plate, will be bolted to the flycut area on the engine frame with slots for adjusting the timing chain slack.  The cam, once the depth has been set, will be cinched down by three setscrews.  If it has a tendency to wander, a bit of Loktite will hold it in place.  Valve timing will be accomplished by rotating the camshaft in the sprocket then cinching-up the setscrews.  The crankshaft sprocket is keyed to the shaft.

 

The ignition trigger magnet will be mounted on the camshaft sprocket and the sensor will be mounted on a slider that is concentric with the camshaft.  Ignition timing can be changed on the fly by rotating the slider to move the sensor.

 

I'll have to tear out the electronics and replace them with a simple ignition/governor circuit.

 

Governor latch-out will be accomplished by raising a pin to hold the cam follower up.  Actuation will be via electromagnet.

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14 November 2010:

I got the flat steel pieces finished today and am well on the way to getting the camshaft frame done.

Camshaft frame welded and squared-up

As you can see, I milled an 0.062" deep slot 1/2" wide as an accurate locator for the center piece of the cam frame.  The center piece was milled on all four edges so it would sit truly perpendicular to the piece it was welded to.  I clamped up the two pieces (lower and vertical pieces in the photo above) and made sure they were in position then welded them together.  After they cooled, I put the frame back into the mill and did a light cut on the surface that bolts the vertical piece to the upper horizontal piece, which also had an 0.062" slot.  The light cut was to correct for the unavoidable slight warpage due to welding.  After it was squared-up, the upper and lower plates were only 0.002" out of parallel.

 

Camshaft frame bolted to engine frame

I removed the outside plate (in the above photo) and milled four slots for the 1/4-28 mounting bolts on the engine side plate.  The slots enable adjustment of the timing chain.

 

Tomorrow, I will start on machining the engine side plate for the camshaft frame.  The camshaft bearing bores will be done with the camshaft frame assembled so they line up correctly.  The design ended-up being a bit complicated but I need the experience anyway.

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16 November 2010:

I'm about finished with the camshaft frame.

Camshaft frame with chain test fitted.

I've still got to make the cam follower and sliders, the outboard bearing cap and the timing assembly but it's coming along.  In the photo, you can see the governor latch pin.  It's shown in the latched position.  It will engage a slot in the cam follower, holding the exhaust valve open about 0.100".  I've still got to work out the actuator magnet for the latch.

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19 November 2010:

It took a while but I've got the cam follower made and fitted.  The time consuming part was the filing and getting it to work smoothly.

The cam follower, showing the governor latching arrangement.

The cam follower slides in the slot as shown above.  There is a slot milled in the bottom edge of the follower that, when the governor latches, engages the pin shown, holding the valve open.  The ball bearing is the cam follower roller.


Valve beginning to open .

Valve fully open.

The cam follower slides on the two brass slippers.  These were also tricky to make, requiring a bit of filing and some very light mill cuts.  It's presently just a tiny bit on the tight side, having a couple of spots where there is some drag but I figure that, once the engine has run a bit, the assembly will "break-in".  The hole you see in the right-hand end of the follower is the socket for the pushrod to fit into. 

 

Cam bearing end plug and ignition timing components.

Next, I made the cam bearing end plug which goes into the outside of the outer frame to hold the cam in position.  To the right are the ignition timing components.  The phenolic ring will be drilled and tapped 6-32 and will be held in place against the inside of the outer frame with the same screws that hold the end plug in position.

 

The phenolic ring has a step diameter just a shade deeper than the arm (the top steel part).  This diameter is a close fit to the hole in the arm.  When assembled, I will put a very slight bend in the steel part so it will turn on the phenolic with some drag.  The Hall-effect transistor ignition sensor will be mounted on the arm and the trigger magnet will be epoxied to the large timing gear.  Note the dimensional changes due to differences in material.

 

At this point, the only part that is still needed is the pushrod.  This should be a trivial job.

 

Once this is finished, I can fit the timing chain and button up the valve gear.

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20 November 2010:

I got the ignition timing setup finished and it should work fine.  


Finished cam frame with ignition trigger.

Side view of ignition trigger.

If you will note, I've added a 10-24 screw and locknut to the cam follower below the pushrod socket.  This is because while fiddling with the governor latch, I wasn't happy with the amount the valve was held open when latched.  Since this is determined by a slot milled in the cam follower, to change it I drilled and tapped a hole that intersected the slot.  Now, moving the screw in or out changes the amount the exhaust valve is held open.  The way it was before with so much slack, it would have been noisy when latched-up.

 

Next, I tackled the governor latch magnet.


Governor latch magnet.

Governor latch magnet in approximate position.

I rooted around in my junk solenoids and relays and found the coil above.  I don't know what it came out of but it must have once energized a now dead contactor.  All I saved was the coil and core.  The coil is rated for 220 volts AC but, with DC, it draws about a half amp at 13 volts and appears to be strong enough to do the job.  Time will tell.

 

The magnetic "circuit" consists of scraps of steel.  In the photo the armature hasn't been mounted and is just sitting in position.  I'm thinking of using the coil spring shown and the left end of the armature could pivot on a couple of pins threaded into the top of the left pole piece.  Alternatively (I had a brainstorm coming in from the shop), I could make a leaf spring to go over that end.  This would serve two purposes.  One would be to keep the armature in position and the other would be to act as the return spring.  I've got some "experienced" steel strapping that should be springy enough to do the job.  Tomorrow, I'll fiddle with it. 

 

The governor latch is designed to be latched ("miss" cycle) when the magnet is de-energized.  Energizing the magnet pulls the armature down and pulls the latch pin down and out of the slot in the cam follower.

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21 November 2010:

Didn't have a whole lot of time today but did get the latch magnet spring worked out.  First, I tried the strapping but what I had was just too stiff.  Then I tried a piece of old clock spring.  It would have worked but I snapped the only piece I had when trying to bend it.  I ended up making a kind of weird spring out of some music wire.


Latch magnet with armature, spring and latch rod.

Latch magnet in position.

I still have to mount the latch magnet and adjust the length of the latch rod but it looks like this ought to work all right.  I'll know for sure when it's all bolted down and I can energize the magnet to see if it can pull the latch rod down.

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22 November 2010:

I got the valve gear and governor latch tweaked and mounted on the engine frame.  The timing chain is in place and the valve timing is set.  I think the latch mechanism is going to work fine but only time will tell if it's robust enough.

 

After moving the partially assembled engine back onto The 2009 Algore Edition Hybrid Green Hoyt-Clagwell (it doesn't weigh too much in this form), I took a look at the piston and rod.  Horrors!  The wrist pin needle bearing was really rough.  I pressed the pin out and found that the wrist pin was brinnelled where the needle rollers bear against the pin.



Failed needle bearing wrist pin.

The rest of the afternoon was taken up pressing out the needle bearing and making a bronze bushing for a new pin.  The majority of the time was spent fitting the bushing to the pin.  It's still tight but I'll go out and work up a sweat once in a while working it until it loosens up enough to finish breaking-in on the engine.

 

Tomorrow, I'm going to make-up a new exhaust port plate.  When I'm done with that, I can start on the electronics.  It should be a simple matter of a day or so but Mr. Murphy has a habit of making the job last longer.

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24 November 2010:

The engine is now mostly back together.  All I have yet to do is to sort out the mixer.  Since it's now located beneath the head, I may have a fuel flow problem because the jet may be below the level of the fuel in the tank when it's full.

Engine going back together.

While I was at it, I made a wooden handle for the crank.  Note the copper line for the exhaust port.  The fitting in the exhaust pipe has been brazed in place.

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29 November 2010:

Well, it's been a long five days.  I got the mixer set-up so fuel fed properly then attacked the electronics.  After a couple of iterations, I had it working the way I wanted it to.  

 

I hooked everything up and cranked 'til I was blue in the face!  It wouldn't hit a lick.  Tried another known good plug but it was so flooded it wouldn't even make smoke.  Since my arm was tired, I hooked-up my variable speed DC motor and belted it to the flywheel.  With the motor turning the engine, I finally got it started by fueling it with naphtha.  

 

Then, I switched it back to gasoline and motored it to run.  It ran right up on the governor and acted about like it was supposed to except for misfiring the first two or three times over compression when unlatched.  A bit of fiddling resulted in putting the spacer back into the intake valve spring and using a slightly stronger exhaust spring.  I noticed that the engine ran fine with the choke fully open so I decided to enlarge the choke opening.

 

Mixer with 1/4" choke opening.                                  Milling choke opening.
 

Mixer with 5/16" choke opening.

It was a simple matter to set the mixer in the mill and run a 5/16" cutter along the opening.  With the choke opened-up, the engine produces more power because more air is allowed to enter the venturi and, to keep the mixture correct, all that needed to be done was to open the needle valve a bit more.  More air + more fuel = more power.

 

This afternoon, I did some tweaking on the speed control and it will idle at around 400 RPM and tops out at about 1,000 RPM.  Although it doesn't seem to be straining to do 1,000, it seems to be happiest at about 800-900 RPM.

 

Driving the tractor around proved that the engine makes significantly more power than it did with either of the previous valve actuator options.  No wonder reduction and cam ended-up being the valve actuation of choice for engines.

 

The 2009 Algore Edition Green Hybrid Hoyt-Clagwell almost ready for prime time.

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1 December 2010:

Now, for all of you Nerdy types, here's the schematic of the circuit I used for the ignition/governor arrangement.  Of course, if you want a clearer image, all you have to do is to click on it.  

 

R5 is the panel speed adjust pot that gives a speed range of from about 350 RPM to 1,000 RPM.  R6 sets the maximum speed of the engine.

 

I had to add C10 right at the sensor because the first Hall-Effect sensor I used went bad after about an hour of running.  I think it died because of an induced spike on the supply line in the cable.  We'll see if that fixes the problem.

Ignition/Governor circuit for The Non-McVickerish Engine.

The circuit has an oddity or two.  First is R8 and C7.  These were added to give the governor some hysteresis.  Also, R5 is an oddball value but I just happened to have an out-of-tolerance pot that was exactly the value I'd calculated for the circuit.  Oh, yes - I just noticed a ground connection dot (beside C7) that is out of position and I ain't a-gonna change it!

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26 December 2012:

After removing the engine from the 2009 Algore Edition Green Hybrid Hoyt-Clagwell in order to install the new 30-60 semi-replica, the Non-McVickerish was set aside along with the circuitry for the ignition and governor.  A few days ago, I dragged it out of exile and mounted it on a skid, provided a cooling tank, revisited the exhaust port and re-mounted the electronics.  It's now going to be a trailer-queen show lady.

Revised exhaust port.

When the engine was originally converted from the McVicker valve actuation, I simply connected the port that drove the valve actuating cylinder to the exhaust pipe.  While converting it to skid mount, the exhaust port block was redesigned with bigger bores and the outlet direction was changed to the other side of the engine.

   

The Non-McVickerish running with new exhaust port.

The engine was run for about a half hour today and, once some spark plug problems were worked out, ran well through it's speed range.  Further improvements will include a bit more "dwell" in the ignition which will result in a hotter spark.  I may also maching some "personality" into the flywheel.

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28 December 2012:

And here is the latest flick:

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5 January 2013:

I've been busy since New Year's.  First, I completely rebuilt the ignition/governor PC board.  Once in a while, it would just take off (run away).  The problem was found to be some not-so smart wire routings on the board.  While I was at it, I added a voltage regulator to the digital part of the circuit.  It's now doing fine.

While testing it a few days ago, I noticed that, even though it ran very steadily with the new circuit board, doing one hit for 18 latchout strokes, the exhaust valve regularly operated twice even though the engine fired only once per cycle.  My theory is that the flywheel was too heavy, causing the engine to speed-up too slowly for the governor to detect the latch speed until the valve has started opening again.  It didn't fire the second time because, by the time it was at the end of the compression stroke, the "spark saver" had engaged.

Because, in addition to lightening it a bit, I wanted to "pretty-up the flywheel some, I took it off and spent some (not-so) quality time with it.

   


   

Machining the flywheel.

As usual, machining the flywheel was the same as machining any flywheel from billet.  The job is a real pain in the patootie if you don't have a big enough lathe.  I made a couple of arbors, one for the rotary table and one for the 7/8" collet in the mill.

The wheel was mounted to the rotary table and a lot of time was consumed in slowly rotating the wheel while milling off 1/8" depth at a time until I had two grooves 1/2" deep.  One of the grooves was for the larger diameter of the "dish" area and the other was for the smaller diameter of the "dish".  The "dish is 1/2" deep so it took four very slow (about 12 minutes each!) 1/8" passes for each of the "rings".  Then, once the depth was finished on both rings, I stepped the cutter in about 0.040" per pass to merge the rings.  This also took a while to do.

After both sides were done, I changed arbors and put the wheel up in the mill spindle and, using the mill vise to hold a cutter, chamfered the three edges on each side of the flywheel.  Needless to say, this is NOT one of my favorite things to spend three days doing!  It does look nice, though.

Tomorrow, I'll roll the engine outside and give it a spin to see if it still cycles the exhaust twice per latch cycle.

Sporting it's new flywheel look.

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10 January 2013:

After a few more iterations of the circuit, I've got the latch to work right.  Under no load, it now unlatches, fires then latches again.  The second exhaust valve opening is eliminated.


What I ended up doing was add a second magnetic sensor to trigger when the exhaust valve is open.  This was the signal to make the decision whether or not to engage the latch.  Since the valve is open, the latch is unblocked and the pin can engage with the cam follower to hold the valve open.


Sensors
   

Cam side                                                                                                Exhaust side

In the left-\hand photo, you can see the arrangement of the sensors.  The camshaft rotates clockwise from this perspective.  At the top, under the projection (the spark timing lever) is the spark sensor.  Clockwise from the spark sensor on the cam sprocket, you can see the magnet that triggers both sensors.  Clockwise from that, attached to the copper tab is the cam sensor.  You will note that the spark sensor and the cam sensor aren't at 180 degrees from one another.  This is because, in order to take the delay in latching (de-energizing) the latch magnet (below the cam assembly with the spring) makes it necessary to trigger the latch several degrees ahead of the cam follower coming off the high point on the cam.  It took a couple of positionings of the cam sensor to get it to work right but now, it latches fine between about 200 RPM and about 1,000 RPM.


While I was at it, I made an exhaust system for it.  I exit the ported exhaust with 1/4" pipe, turn it 90 degrees and engage the 1/4" pipe into a bushing in a piece of 1/2" pipe.  The 1/4" pipe was turned to 1/2" O.D. to fit into the 1/2" bore of the bushing.  This is a slip fit to compensate for expansion and contraction so as not to put a strain on the fittings.  The muffler is one I originally made for the Homebrew Hvid and which proved to be an inadequate silencer.  It works fairly well with this engine, removing the bark from the exhaust.

I think the Non-McVickerish Engine is now ready for prime time.  Here's the last (I think) movie showing it running with the proper valve sequence.

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BOY!  This is fun!

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If you have any questions or comments, please email me at:  [email protected]