# Heavier flywheels for the Kerzel hit and miss engine



## Brian Rupnow (Nov 29, 2016)

About 6 or 7 years ago, when I first started machining, the Kerzel engine was the first hit and miss engine I ever built. After many trials and tribulations, I ended up with a successful runner. You can see the lengthy build thread here. http://www.homemodelenginemachinist.com/showthread.php?t=10091--Although this engine worked very well, and went into and out of hit and miss mode as I had hoped for, it never gave that distinctive "pop"---hiss-hiss-hiss "pop"---hiss-hiss-hiss sound that you associate with full size hit and miss engines, or even many of the model Farm-boy engines I have seen built. I decided that this was the result of my using a Viton elastomer ring on the piston instead of a cast iron ring. The Viton ring seals perfectly, but it creates more drag on the piston than a cast iron ring would. I have often wondered over the years, if an increase in flywheel diameter would have a positive effect on the way my engine ran. A recent post on HMEM by a gentleman named Jim, showed that he built a Kerzel a few years ago, and failed to get it running at all until he made a set of oversize flywheels for it. This got me thinking about my own Kerzel again, and prompted me to measure how much clearance  I had between the existing 3 1/2" flywheels and the wooden base. I just have room to slide a 1/4" thick piece of cold rolled flatbar between the brass flywheel and the base. The gas tank can be slid over 1/4" more to the right to clear a larger flywheel.A phone call to my metal supplier determined that he has a piece of DOM tubing, 4" outside diameter and 3" inner diameter, and that he would saw off a couple of 7/8" thick "rings" for me for $5 each. Since I have exhausted my ideas of "nifty things to build" for the moment, I am going to see if increasing the diameter of the flywheels has any effect on how it runs. The picture here shows my kerzel, setting up on it's shelf, and you can see the 1/4" of clearance under the existing flywheel.


----------



## Brian Rupnow (Nov 29, 2016)

This is a video link to the way my Kerzel engine runs now. This is a fairly recent video, taken within the last three months.
[ame]https://www.youtube.com/watch?v=dLkF2nAjOJ8[/ame]


----------



## Brian Rupnow (Nov 29, 2016)

This is the best running Kerzel I have ever seen.
https://video.search.yahoo.com/sear...=80278183de297601e179f80b616b40e3&action=view


----------



## WSMkid (Nov 29, 2016)

Brian,
 The other day I was thinking about these model hit and miss engines and amount of "coasting" they do. Exhaust valve size crossed my mind. 
Would increasing the exhaust valve to the max the bore/head would allow (and ports down stream) for better costing. This thought came to me after planing out bigger valves and some port work on my 450 race four wheeler. 

Being stuck at school for 16 hours a day I haven't had time to do any building but I have added this to my list of things to try after I have a shop set up. 
 Just food for thought. 

I love your recent builds, I will be following this one as well. Always something to learn!

Garrett.


----------



## Brian Rupnow (Nov 29, 2016)

WSMkid --Thank you for stopping by and saying hi. I don't think that there is enough restriction in airflow caused by the current size of the exhaust valve to have much effect on how long the engine coasts between hits. The current valve and port size will flow more air than the engine can pump.---Brian


----------



## Brian Rupnow (Nov 30, 2016)

Yesterday about 10 minutes after I posted about this flywheel upgrade, a walk-in customer showed up at my door with about 6 hours of machining he needed done. I had to go across town to pick up some 304 s.s. for his job, so I picked up my material for the heavier flywheel rims as well. I have no idea why my supplier cut one ring 1/4" thicker than the other, but for $5 I wasn't about to ask him. I will finish off the customer job this morning, and then see what I can do to machine these rings into respectable flywheel "add ons".


----------



## Brian Rupnow (Nov 30, 2016)

I am going to try for this. The new added weight will be attached to the existing assembly with Loctite 638.


----------



## Brian Rupnow (Nov 30, 2016)

Ha!!! That went amazingly well!!! I had to shift the gas tank about 3/8" but other than that the first flywheel slid right into place. Now to turn the i.d. on the second blank.


----------



## Brian Rupnow (Nov 30, 2016)

Yee Hawwww---Lookit the ears on that sucker, Roy!!! I'm not sure what's going to happen with this additional weight on the flywheels, but for $5 and an afternoons work I'm going to find out. I ended up turning the outside diameter of the add-on flywheels to 3.960", just to have a breath of clearance between the flywheels and the wooden base. The only things I had to change were the position of the gas tank and the knob on my Kerzel lever pivot shaft. The gas tank was easy, as it was just Loctited into an aluminum hoop, and the Kerzel lever pivot shaft knob which used to be round is now cylindrical. Everything goes round and round and up and down with no clearance issues, so hopefully tomorrow I'll find out what effect this has on the way the engine goes in and out of hit and miss cycles.


----------



## jimsshop1 (Dec 1, 2016)

Looks great Brian. Kind of like opposite of my Flywheels-brass steel, steel brass, I like the contrast. BTW, do you still have the PUMP JACK plans? I'm an old OIL FIELD guy and always wanted to build one.

Respectfully,

Jim


----------



## Brian Rupnow (Dec 1, 2016)

jimsshop1 said:


> Looks great Brian. Kind of like opposite of my Flywheels-brass steel, steel brass, I like the contrast. BTW, do you still have the PUMP JACK plans? I'm an old OIL FIELD guy and always wanted to build one.
> 
> Respectfully,
> 
> Jim


Jim--send me an email to [email protected] and identify yourself and what you want and I will send you a download link for the plans.---Brian


----------



## Brian Rupnow (Dec 1, 2016)

This is the first run with heavier flywheels. It is somewhat inconclusive at the moment. I think there is a bit of noise "illusion" here, because my muffler points down away from the engine, and you can not clearly hear it when it "hits". I may modify the exhaust pipe and bring it up to the top so "hits" can be heard more clearly. It is still going in and out of hit and miss mode with the heavier flywheels on it, but seems to be running a bit fast. I may add a bit of weight to the counterweights, as this is much simpler than winding different strength springs.
[ame]https://www.youtube.com/watch?v=lBhIjjYzVyE&feature=youtu.be[/ame]


----------



## Brian Rupnow (Dec 1, 2016)

In order to hear more clearly when the engine fires, I have converted to a stack style exhaust. You can see the old muffler setting beside the engine. the new exhaust is a two piece unit., A brass part is machined to screw into the exhaust port on the cylinder head with a 5/16"-18 thread. The stack itself is made from a section of high nickel content automotive brake line. It is pushed into a hole in the brass machined part and held in place by #620 Loctite. The string tied to the stack has a pair of pliers hanging off the other end, to ensure that the exhaust stack is held truly vertical until the Loctite sets up.


----------



## Brian Rupnow (Dec 1, 2016)

I'm finding out interesting things here. The added weight on the flywheels made the engine want to run slower. The fact that the engine was running slower made the governors operate in a different range because of the slower speed, and strangely enough the engine actually ended up running faster!! The cure for this was to add a bit of weight to each governor weight, which made the governor more sensitive and consequently brought the speed back down to an acceptable level. I'm just about where I want to be in terms of speed and hits versus misses, but I have a terrible rattle in the engine. I don't know if this is a result of the needle roller bearings on the crankshaft (they were noisy right from the day I put them in 6 years ago, in an effort to cut down on friction) or just the sound amplification caused by running the engine on my wooden desk. Tomorrow I will try it on the workbench out in my main garage it is any quieter.




[ame]https://www.youtube.com/watch?v=m2QLVUGCB_o&feature=youtu.be[/ame]


----------



## Brian Rupnow (Dec 1, 2016)

I'm pretty sure the noise is in those roller bearings. As I said, they were noisy right from day one. I'm having a new thought here. This is a low rpm engine. There is no real side-load on the bearings, other than the thrust of the connecting rod. I have had similar applications in real life full size engineering projects, where I used type 901 blue nylon. It has a very low coefficient of friction,  it's not affected by oil, and it's tougher than whalebone.  The shaft is loose in the bearings. I can grab a flywheel and move it up and down. Not much, but probably enough to produce the rattle. Tomorrow I am going to call some of the plastics people here in Ontario and ask about this.


----------



## Brian Rupnow (Dec 2, 2016)

Well, in for a penny, in for a pound!! Once I seen that I could grab either flywheel and move it around a bit in the needle roller bearings, it was pretty apparent where the noise was coming from. I pulled the crankshaft this morning. Back when I decided to run needle bearings, I had to make up spacer bushings, as the roller bearings were 3/8" i.d. x 0.5625" o.d., while the hole in the Kerzel frame was 0.625" diameter. I see that I also made the spacer bushings in a "top hat" configuration, so that the flange would act as a spacer facing towards the center of the engine. I have talked to some of the nylon specialties people this morning, and found that there is a specially formulated nylon "Nylatron GS" with molybdenum as part of it's make-up, which is recommended for use in bearings for motors. My local metal supplier has an off-cut of this material, and I am going to make up two new bushings from it and get rid of the needle roller bearings. One of the benefits of these nylon bushings is their noise deadening capacity. It is not a lot of work to make two new nylon bushings, just a huge pain in the butt having to redo the valve timing and ignition timing.


----------



## ShopShoe (Dec 2, 2016)

Regarding the desktop amplification: Try an old mousepad under the engine. I think the clamps should still hold things well enough in that situation.

However, I think you may be right about the bearings being the main source of the rattle. (Would mechanic's stethoscope or piece of tubing help you isolate it?)

I am enjoying the reworking of this engine. I remember when you built it.

--ShopShoe


----------



## Brian Rupnow (Dec 2, 2016)

For what it's worth--I just pulled everything off one end of the crankshaft and miked the area which fits into the bearing. It mikes at .002" undersize. I thought, Hmmmm, that shouldn't have given all the wobble I was seeing. Then I tried the 0.375" shank end of a milling cutter (which is not undersize at all) into the roller bearing and it STILL wiggled around quite a bit.


----------



## Brian Rupnow (Dec 2, 2016)

The other end of the crankshaft measured about .003 to 0.006" undersize at the bearing journal. That is definitely too much too much. This is a built up crankshaft, and I distinctly remember the crank going through a few indignities back when I first built the engine. I am going to put new ends on both ends of the crankshaft while I have everything apart.


----------



## Brian Rupnow (Dec 2, 2016)

The old crankshaft was silver soldered and pinned together, and although it was straight it had suffered a few abuses along the way, not the least of which was being a bit undersize at the area in contact with the bearings, and being fairly chewed up by set-screws at the outer ends. I cut one end off with my bandsaw and chucked the other up in my lathe. After center drilling I drilled thru both webs with a 1/4" drill, then with a 5/16 drill, then with a 11/32" drill. Now there was only a very thin wall of material holding the center portion to the end in the lathe chuck. I then ran thru with a 0.3735" reamer, which separated the center portion completely from the end in the chuck. Note that the reamer is 0.0015 inches less than 3/8". The new crankshaft  pressed into place is a piece of drill rod. Why is that, you may ask?--Because, drill rod comes at a full 0.375". Cold rolled rod comes in at 0.005" undersize, generally about 0.3745". I wanted as much "press" as I could get, so I used drill rod. I don't want to disturb the con rod journal by heating anything up to silver solder the new crankshaft into place, so it is pressed, Loctited, and will be cross-drilled and pinned. Then after 24 hours for the Loctite to fully set, I will cut out the piece remaining between the crankshaft web plates.


----------



## Brian Rupnow (Dec 2, 2016)

And oh yeah--I put a spacer between the outer edges of the throw sideplates opposite of the rod journal before I pressed the new crankshaft into place, so as not to collapse anything.


----------



## Brian Rupnow (Dec 2, 2016)

The crankshaft has been cross-drilled, reamed, and had 3/32" dowel pins Loctited into the reamed cross drilled holes. I ended up with a 1 3/4" diameter piece of super duper molybdenum nylon from my metal supplier. It was a short left over from a job they had done. I have never machined nylon before, but I had read that medium high speed and very sharp tooling was the trick. I ran it at 400 rpm and used a new hss lathe tool and it was beautiful to machine.


----------



## Brian Rupnow (Dec 3, 2016)

HELP!!!---I am getting ready to reassemble this engine, and I can not find anything in my notes, build thread, nor original David Kerzel drawings about the exhaust valve timing. I think it should begin to open at about 50 degrees before bottom dead center on the power stroke but I can't confirm that. Does anybody see or know where Kerzel gives that information.---Brian


----------



## Brian Rupnow (Dec 3, 2016)

Everything is back together again with new crankshaft and Nylatron bushings. Flywheels have gone from being rather "loosy-goosey" to "Oh my gosh, that feels snug"!--A word for any first time builders following this thread--If when you first assemble a crankshaft assembly it spins freely in the engine, odds are about 95% that after the engine has ran for half an hour, everything will be too loose. On the other hand, if everything is too stiff, then you won't be able to get the engine to run to free itself up. This is kind of a moving target, and although experience certainly is a big asset, even after 24 engines I still have to guess at it a bit.


----------



## jimsshop1 (Dec 3, 2016)

I think that's way too soon Brian. If I remember right mine is about 15 degrees BBDC. But maybe not

Jim


----------



## Brian Rupnow (Dec 3, 2016)

As Robbie Burns once said "The best laid plans of mice and men, gang aft agley!!"---and mine seen to have went "agley" today. I hunted around until I confirmed that the exhaust valve on the kerzel should begin to open when the piston is 50 degrees before bottom dead center. I set the ignition timing---In fact I set it many times today. NO JOY---the engine fires like a devil, but I can't get it to keep running. I have tried all of my usual (and some rather unusual) tricks, and I do not have a runner. My wonderful new Nylatron bushings seem to have a great deal of "stiction"---resistance to free rolling of the crankshaft. I have one trick left in my arsenal of "things to try". I may just pull the sparkplug, coat everything that moves liberally with lubricating oil, mount a pulley on one end of the crankshaft and let my 1/2 horsepower electric motor drive things for a couple of hours. If that doesn't loosen up the "grabbiness" of the Nylatron bushings, then we will move on to plan "D". Plan "A" was 660 bronze bushings, which wore out very, very quickly when I first ran the engine 6 years ago. Plan "B" was to use the roller bearings, which worked, but was very noisy. Plan "C" was the Nylatron bushings which are currently installed. Plan "D" will be to pull out the Nylatron bushings and install a set of Oilite bronze bushings. I haven't changed anything on the piston nor the valves, so lack of compression is not a factor here.


----------



## Brian Rupnow (Dec 4, 2016)

Lincoln, Lincoln, I been thinkin'-----If I take this thing apart again to change to yet another set of bushings, I think maybe I will completely forgo bushings and go straight to ball bearings. This involves making a few more parts which bolt directly to the existing base to capture the ball bearing. The ball bearing is the same one as was used in the Rupnow vertical engine, only this time I won't get sealed bearings. Sealed bearings are great if there is a lot of contamination around or if they are hard to access to lubricate. However, the seals do create a small amount of "drag" and in the case of this hit and miss engine they are quite accessible for a squirt of lubricating oil, and there is really no contamination around the bearing. I have about 500 little scraps of aluminum plate kicking around, certainly enough to make the new pieces without buying material. I'm a bit disappointed in the Nylatron bushings, but if you don't try something a bit different sometimes, then you never learn anything new. After playing with the engine for two hours to try and get it started, the Nylatron bushings had loosened up quite a bit. After setting overnight and cooling off, they are all "Grabby" once again this morning.


----------



## Brian Rupnow (Dec 5, 2016)

Oh, my poor old Kerzel. Heavier flywheels I said. Yeah----Which lead to different bushings. which lead to ball bearings instead of bushings---which lead to new bearing support side-plates and caps. And since we have everything apart, we might as well put a new Viton ring on the piston. And put the whole engine in the tank and get 6 years accumulated dirt and grease off it. The new side plates and caps are semi finished---I didn't want to put the mounting holes in the sideplates until I had taken the engine apart to confirm that I actually have the mounting holes in the base where the drawing says they are. I do!! As well as a plethora of other holes that were put in for various reasons back when I first built the engine. Fortunately, when the new ballbearing sideplates are mounted all of the "extra" holes will be covered up.----Sure am glad I enjoy this!!


----------



## jimsshop1 (Dec 6, 2016)

Brian Rupnow said:


> Oh, my poor old Kerzel. Heavier flywheels I said. Yeah----Which lead to different bushings. which lead to ball bearings instead of bushings---which lead to new bearing support side-plates and caps. And since we have everything apart, we might as well put a new Viton ring on the piston. And put the whole engine in the tank and get 6 years accumulated dirt and grease off it. The new side plates and caps are semi finished---I didn't want to put the mounting holes in the sideplates until I had taken the engine apart to confirm that I actually have the mounting holes in the base where the drawing says they are. I do!! As well as a plethora of other holes that were put in for various reasons back when I first built the engine. Fortunately, when the new ballbearing sideplates are mounted all of the "extra" holes will be covered up.----Sure am glad I enjoy this!!



I'm sorry Brian, I feel like I started all this:wall:


----------



## Brian Rupnow (Dec 6, 2016)

Jim---Never waste time being sorry for things you didn't do. If you're like most men, the time would be better spent feeling sorry for things that you DID do (Just ask Mrs. Rupnow.). I have never been totally happy with my Kerzel ever since I built it. Oh, it was a big thrill when it first ran. And an even bigger thrill when I got the hit and miss working. It's just that the hit and miss function has never worked as well as other home built hit and miss engines I have seen on the internet. This has been coming for a long time. I have known for a few years that I was going to do this when the time was right.---Brian


----------



## Brian Rupnow (Dec 7, 2016)

We are getting into the home stretch now. New sideplates and bearing caps have been made and installed, and in this picture I have just counterbored one sideplate for a #1606 ball bearing. The bore is finished, about .002" over so the bearing slips in easily. I now have to flip the engine over, center on the pilot hole that is reamed to 7/16" dia. and bore the other side. I made bolt on bearing caps so that I can take the caps off and lift out the entire crankshaft assembly, bearings and all without disturbing the sideplates. If the fit is good enough on the bored holes, I will lay a piece of 0.015" thick gasket material on top of the bearing and tighten down the caps to lock the outer race in place. I haven't decided yet whether to leave the seals in the bearings to retain grease, or pop the seals out, which gives a lot less friction but requires that the bearings be oiled from a squirt can.


----------



## jimsshop1 (Dec 8, 2016)

Nice job Brian. You will have it back together in no time! I think I may at sometime in the future replace the bronze bearings in mine with ball bearings as I have already replaced them once. Where do you get those ball bearings? BTW I finally got mine to hit- miss regularly but I'm still experimenting with spring tension on the governor weights to get the speed down.

Regards,

Jim


----------



## Brian Rupnow (Dec 8, 2016)

I buy all of my bushings and bearings thru Canadian Bearings in Barrie. They have 1 to 2 day delivery of all the main brands. Congratulations on the hitting and missing. If you want I will post the drawings for the new sideplates and bearing caps that fit the holes in the existing base.


----------



## Brian Rupnow (Dec 9, 2016)

At the very last minute, I decided to pull the seals out of the bearings. There is no contamination around the engine to get into the bearings, and they are readily accessible for a few drops of oil from my squirt can. I went to Hercules O-ring this week and bought a lifetime supply of Viton O-rings for 3/4", 7/8" and 1" bore engines. I have been buying onesies and twosies for 5 years, but the last time I went over I got some flack about it. So--I bought a minimum size pack which contains 25 of each size.  I put a new o-ring on the engine while I had everything apart. I have almost everything back together, and should finish re-assembly sometime this afternoon. It is hard right now to make a judgement call on how much the ball bearings have loosened things up, but I should know by the end of today.


----------



## Brian Rupnow (Dec 9, 2016)

Somehow, today I must be paying for past sins. I have everything back together, good spark, lots of gas , great compression, perfect valve timing---and I still can't get the engine to run. I haven't had to work this hard at getting an engine to run in years. We're having a blizzard outside today and it's been nice not to go out of the house. I worked all week at a factory on the other side of town designing new tooling for spin-forming lathes, so I was looking forward to getting the engine up and running today. I'm not exactly sure what I will try next, but I may put one of my other carburetors on it temporarily.


----------



## Brian Rupnow (Dec 9, 2016)

All I had to do was complain a bit on the internet--and tweak the valve timing a very little bit--and I have a runner!!! tomorrow I will see about hooking up the Kerzel lever to get some hitting and missing happening.


----------



## Cogsy (Dec 9, 2016)

I'm just thinking here Brian, but if the valve timing was stopping you from running, and you only tweaked it a little bit, then I'd guess there is potentially still some power to be had by fine tuning the valve timing further in the direction of your 'tweak'. 

Also, I see you mentioned the exhaust valve opens 50 degrees before BDC, maybe this is a bit much for a slow running hit and miss engine? The idea is to give the cylinder pressure enough time to equalise with atmospheric pressure before the piston begins it's upstroke, so the slower the piston is moving the fewer degrees early the exhaust valve needs to be opened to get rid of the excess pressure. As long as the pressure is equalised by BDC, every extra degree you can keep the exhaust valve closed is extra power.


----------



## Brian Rupnow (Dec 10, 2016)

Cogsy--today I need to research this a bit more. I am having trouble finding good information on it. Last night I got out my "Shop Wisdom of Philip Duclos" and read up on his recommendation on valve timing on a hit and miss engine that he designed, and he too recommends that the valve just begins to feel the cam influence at about 1/8" before the piston reaches bottom dead center. if I can find better information somewhere, and it works for me, I will let you know. The engine is running now, but it seems rather "weak" is the best way I know how to describe it. I have a new piston ring on it, and the valves haven't been changed in any way from when I started this rodeo.


----------



## Brian Rupnow (Dec 10, 2016)

I am finding things out as I tune this hit and miss engine. I initially had the exhaust valve set to begin opening at about 50 degrees before the piston reached bottom dead center. This puts the bottom of the piston skirt about 0.145" away from the end of the cylinder. No joy----Much popping and firing along with the drill motor I use as a starter, but no way it was going to run without the drill motor. I tried various ignition timing, ranging from no advance to 15 degrees advance, and every possible needle valve setting but it wasn't going to run. I did a bunch of internet research on exhaust valve settings for hit and miss engines, but got a lot of conflicting information there, ranging from 50 degrees advance on the exhaust timing to no advance on the exhaust timing. I began to decrease the exhaust valve timing from my original 50 degrees in approximate 10 degree increments, and immediately began getting sustained runs with the engine. at 40 degrees advance, it would run, but had very little "power", just barely enough to keep it turning over. At 30 degrees advance, it ran better.  I got my test indicator out and positioned it so I could tell exactly at what point the exhaust valve began to open, and decreased the valve timing advance even farther. Finally, I reached the point of no valve timing advance at all, and the engine runs quite happily there. I have found that the ignition timing seems to perform best of all when it is set to fire exactly at top dead center with no ignition timing advance at all.  The engine turns very freely with the new ball bearings on the crankshaft. Somehow there has been enough changes in the dynamics of the engine that it is now running too slowly to make the governor engage the Kerzel lever and go into miss mode. I think I will have to add some more weight to the governor weights to increase the governor sensitivity and get it to hit and miss.


----------



## jimsshop1 (Dec 10, 2016)

Hi Brian,

  I have my exhaust set to begin opening at exactly BDC and the points to open at exactly TDC and the engine runs very nice with just a couple flips of the fly wheel to get it started. I made new weaker springs out of .010 wire to get it to slow down as it was racing to fast for my liking, just the opposite of yours. I have to agree with you that the Kerzel is very cantankerous about it's settings but when you get them correct it runs like a top. Right now I am experimenting with the exhaust pipe to get a louder bark out of it and have so far been quite successful. 

You will get it to run well Brian as I have seen that you never give up until something goes your way!

Have a good day,

Jim


----------



## Brian Rupnow (Dec 10, 2016)

Before I go any farther with modifications to this engine, I have to right an old wrong. When I first built this engine 6 years ago, I had only built one engine before it, the Webster. I had a terrible time getting this engine to run at all, and finally, in a rather desperate move, decided that the cam design per Mr. Kerzel must be wrong. So---since I had great experience with the Webster, I decided to make a clone of the Webster cam to run in the Kerzel engine. As you can see from the attached picture, the grey cam (as per Mr. Kerzel) and the blue cam (as a clone of the Webster cam) are very different. Since I am head and shoulders back into this engine, I will make a new cam according to Kerzel's original plan and install it. The dwell on the blue cam, which I am currently running, is about 4 times greater than the cam designed by Kerzel. This has to be having a pretty radical effect on the engines performance, so I will make a new cam and install it before I do anything else.


----------



## Brian Rupnow (Dec 10, 2016)

Jim--What are you doing to give your exhaust a louder bark?


----------



## jimsshop1 (Dec 10, 2016)

Brian Rupnow said:


> Jim--What are you doing to give your exhaust a louder bark?



Brian,

  I found a length of thin wall brass tubing that would just slip over the 1/4" copper exhaust pipe, cut it to about 3" long and cut a V slot about 3/16" down from the top about half way through then soldered a cap on the top. I think this makes the sound hit the top and then bounces out the V slot It does make the POP louder. I haven't soldered this on the original pipe yet so I am going to experiment with different lengths. Sure wish I had a CAD program so I could show how I did the extension but I think my explanation is fairly clear.

BTW I made my cam as per Mr. Kerzel's plans.

Jim


----------



## Brian Rupnow (Dec 10, 2016)

Tomorrow I am going to make a new cam, using the Chuck Fellows method. Chuck doesn't want to take any credit for this, saying he learned it from somebody else, but Chuck is the one with the youtube video showing how it is done. It is a really easy way to make a cam, once you get your head around it. If you Google "chuck fellows cutting cam" you can see a video of him doing it. I used that method on the cam for my oscillating i.c. engine, and it worked great. It gives a nice radius to the cam flanks.


----------



## Brian Rupnow (Dec 11, 2016)

So---Here we have the old cam on the left and the new cam on the right. The new cam has since been installed on the engine. I did use the method that Chuck Fellows shows in his YouTube video, and it works so well that I am going to start a separate thread on setting up a cam in a vertical mill to use that method. It is remarkably fast, and it gives a nice flank radius on the cam, instead of just flat sides. This is the second cam I have made using that method, and a large part of today was spent writing down all the "step by step" procedures in setting it up so that I could dial in the dimensions of the cam and not just take a guess at the flank radius being cut. It took me longer to write everything down than it did to machine the cam.


----------



## Ghosty (Dec 12, 2016)

Brian, been using the same cam cutting myself 
Here is the video from Chuck Fellows
[ame]https://www.youtube.com/watch?v=IEtqETL2LXs[/ame]

Cheers
Andrew


----------



## gbritnell (Dec 12, 2016)

Brian,
The shape of the cam lobe can take on a different profile depending on what type of follower or lifter is being used. In the automotive world you can have a flat tappet cam lobe and a roller tappet cam lobe with the same timing specs but completely different shapes. 
Another thing to consider when setting up the timing on a hit and miss engine is the adjustment of the rocker arm for valve clearance. Most of the hit and miss engines that I have built have a lot of valve to rocker arm clearance, not like regular cam operated I.C. engines. By changing the valve clearance, just like on a regular I.C. engine you can change the valve timing. 
As far as flank radius goes, the purpose is to soften the contact between the lifter and the cam. Instead of the cam banging into a flat side it ever so slowly is accelerated into opening. Personally I have never built a flank radius into my cams and have never had a cam wear out even after hundreds of hours of operation. Here again when machining a cam with a flank radius your timing events are going to change because of when the contact between lifter and lobe occur. 
For timing a hit and miss cam lobe it can be opened anywhere from 30-50 degrees before BDC. By then most of the work of combustion has taken place. For closing I always make it as close to TDC as possible. There's no need to have it close after TDC as in a conventional engine because the intake will only open when there is vacuum being created in the cylinder and the longer the exhaust is open the smaller the amount of intake charge will be created. On a conventional engine valve overlap is used as a way of drawing in the fuel charge by the flow of the exhaust as it evacuates the cylinder. 
gbritnell


----------



## Brian Rupnow (Dec 12, 2016)

Thank you George. I knew most of that, but hearing it from a second source, especially from someone with experience is always a very good thing. Knowing my cam profile exactly, I may try working backwards from "closed at top dead center" to see exactly when I should start opening the exhaust valve.---Brian


----------



## Brian Rupnow (Dec 12, 2016)

Okay guys--stay with me on this. It gets a bit theoretical at times---. this is the cam, as designed by Kerzel. Using some cad magic, I "machined" the cam exactly as Kerzel advises in his original plans for the hit and miss engine. I then matched a circle to the resulting profile, and discovered that Kerzel had done his job very well.--the resulting diameter of the circle is exactly twice the base diameter of 0.6". The radius described by this circle is called the "flank radius". I then did a little more cad magic and see that the angle of "cam influence" is 122 degrees. Since the cam revolves at half the speed of the crankshaft, that 122 degrees actually translates to 244 degrees of "influence" at the crankshaft. As the piston moves from bottom dead center to top dead center, the crankshaft revolves half a turn which is 180 degrees. We want the exhaust valve on a hit and miss engine to close when the piston is  right at top dead center, with no overlap, because the intake valve is operated by atmospheric pressure and will not begin to open until that exhaust valve is fully closed. So---we subtract that 180 degrees from 244 degrees. and this tells us that the exhaust valve should begin to open 64 degrees before the piston reaches bottom dead center on the power stroke. This does not take into account any "valve stem clearance", but that amount is very minimal when set to .005". This seems like an awful lot of "lead" on the exhaust valve timing.


----------



## gbritnell (Dec 13, 2016)

Hi Brian,
That is a lot of lead on the exhaust opening but if the cam is made to the drawing a few 'fudge' factors could be used to reduce that number. One would be to increase the rocker to valve clearance. Now I'm not talking .032 or such but by adding another .005-.007 it will change the timing. Another would be to allow the exhaust to overlap TDC by 10 degrees. I know we talked about it but 10 crank degrees would hardly be noticeable. 
I guess not being a mechanical engineer or never having delved into combustion processes that deeply I don't know how much energy is still in the cylinder at given crank angles. 
Ok let's kind of analyze this as amateurs. Ignition timing is set to burn the fuel mixture and create maximum cylinder pressure just as the piston passes TDC. Fuel burns at a constant rate given octane rating and compression pressures so as the engine rpm increases the ignition advance has to increase to create the maximum pressure at the same point. Now once this pressure is created my question is how much useful pressure remains at say 30, 45 and 60 degrees of crank angle. On a multi cylinder engine the cylinder pressure would be less noticeable because there would be another cylinder creating energy but on a single cylinder engine at some point the cylinder energy would be wasted. Along with loss of work the exhaust would have a nice flame coming out of it due to the still burning fuel mixture. 
I like you grew up with hot rods and engines and am pretty well informed on what a cam does to an engine's operation with changing numbers but like I said I don't know the physics part of the equation. 
gbritnell


----------



## Brian Rupnow (Dec 13, 2016)

George--I am in the world of "try it and see" engineering. I'm sure everything you say is absolutely true. I'm sure that Kerzel was probably "right on" with his cam design, as many people have successfully built and ran this engine using Kerzel's cam design. I am trying to search out the mathematical reasoning behind some of the cam design as it realates to engine performance, and how the actual cam shape is determined, then how do we use our manual machines to best machine the cam and be able to end up with a cam that matches the parameters of the "design on paper". I had a crazy thought in the middle of the night. If I machine a piece of steel with the same thread and shoulder as the sparkplug, with a hollow center, then I can slip a piece of neoprene fuel line over it. Assuming that we want the exhaust valve closed when the piston gets to top dead center, we should be able to blow air thru that tube by mouth and have it escape right up until the moment the exhaust valve closes when turning the engine by hand. I know that both of my valves are sealing perfectly, so it would seem to me that as you turn the crankshaft by hand, you will know the instant that the exhaust valve fully closes, because you won't be able to blow any more. This will give a very good way to know that the exhaust valve is fully closing at the correct time in the cycle.---Brian


----------



## Brian Rupnow (Dec 13, 2016)

Finally, we are up and running again. I ended up with the exhaust valve beginning to open at about 50 degrees before bottom dead center and the timing very slightly advanced. Lord, it's been a struggle. I couldn't do the "blow down the sparkplug hole" trick, because although I have a 1/4-32 tap, I don't have a 1/4-32 die to make a fake sparkplug with.
[ame]https://www.youtube.com/watch?v=pZwJBjGehhs&feature=youtu.be[/ame]


----------



## Brian Rupnow (Dec 14, 2016)

Time to put this thread to bed. The video tells it all!!!
[ame]https://www.youtube.com/watch?v=H4gQ5R1oq94&feature=youtu.be[/ame]


----------



## Ghosty (Dec 14, 2016)

Brian, The video comes up as "This video is private".
Just thought you would like to know.

Cheers 
Andrew


----------



## Brian Rupnow (Dec 15, 2016)

Ghosty said:


> Brian, The video comes up as "This video is private".
> Just thought you would like to know.
> 
> Cheers
> Andrew


I fixed it.---Brian


----------



## Brian Rupnow (Dec 15, 2016)

It's time for the Kerzel to go back up on the shelf, but not until it's had a little work session. These little engines set around all over the place in my office, and the only time they get to pay any of the rent they owe me for the space they take up is when they get a chance to do a little work for me. The Kerzel is now paid up for the foreseeable future. You won't see it missing in this video, because it is working under "load".
[ame]https://www.youtube.com/watch?v=cW74MBUU2ZA&feature=youtu.be[/ame]


----------



## Brian Rupnow (Dec 17, 2016)

The inability to get a real good "hit and miss" action is making me twitchy. This is not a good thing. I have ordered a 1/4"-32 die to make a false hollow spark-plug and try my "blow down the sparkplug hole and see when the exhaust valve closes" trick. Damn, if Dick in Ohio can get his Kerzel running a Viton ring to hit and miss so well, I should be able to too!!! I did take 0.040" off both sides of both flywheels, and although it helped, it didn't help enough to satisfy me.


----------



## Cogsy (Dec 17, 2016)

It's just my thinking and might be totally wrong, but I think it is likely the power of the engine which is the limiting factor of how many 'misses' you can get in a row. Basically, a bigger bang from the power stroke will impart much more energy into the flywheels and take longer to bleed off than a smaller 'bang'. So the problem is not so much storing the energy but making it. Again I could be totally wrong here, but in the videos you showed with your Kerzel running without the hit and miss lever, the RPM didn't seem all that high. I thought without the governor the engine would run extremely fast (like the Rupnow Hit and Miss does without a governor) as each hit makes a heap more power. With a bigger flywheel it takes more energy to accelerate it so a lack of power would mean less misses between hits, just like loading the engine. That's why I wondered about your valve timing initially but potentially it's the carb underperforming?


----------



## Brian Rupnow (Dec 18, 2016)

Al, I am inclined to agree with you. The cylinder is only a 3/4" bore, and it doesn't provide a lot of power when it hits. However, I do have a video of the same engine running a viton o-ring, and working exactly the way I would like mine to work.--Brian
[ame]https://www.youtube.com/watch?v=0mgjPH3B5KE[/ame]


----------



## gbritnell (Dec 18, 2016)

Gentlemen,
Getting a hit and miss engine to run slowly is a balancing act. The more compression the engine has the more inertia it needs from the flywheels to get over the compression stroke. On an engine with good compression when you flip it over by hand it takes a good flip to accomplish this. Once that combination is sorted out then by fine tuning the springs on the governor the speed, or miss time can be adjusted until the compression issue reappears. 
On any engine the power is going to be directly related to the amount of air/fuel that the engine takes in and on a hit and miss engine relying on the engine vacuum to open the intake valve isn't the most efficient means of accomplishing this. Again this is a balancing act of using a valve spring with just enough tension to close the valve effectively but not so light that it can't overcome the friction of the valve guide. 
gbritnell


----------



## Brian Rupnow (Dec 18, 2016)

I can just tell that if all the guys on this forum lived within 25 miles of Barrie, they`d all be over in my shop helping to get this engine hitting and missing properly. Everyone is giving great suggestions, and honest, I have tried them all. I have tried heavier flywheels, I have tried lighter flywheels, I have tried one flywheel, I have changed the valve timing so many times that I had to put new socket head setscrews in the crankshaft gear because the wrench hole edges rounded out on the original set screws. I have tried heavier governor weights, I have tried lighter governor weights, I have tried at least 50 advanced and retarded positions on the ignition timing, I have put in ball bearings with their seals removed  to support the crankshaft, I have made a new cam exactly to Kerzel`s original plans, I have made a new crankshaft. I have moved the flywheel with the governor weights closer to the engine, I have moved it farther from the engine (this affects the hysteresis--the gap between the Kerzel lever and the catch on the push-rod assembly). I have put a lighter spring on the atmospheric intake valve, I have put a new viton ring on the piston just in case the 6 year old ring was worn out. I have set the valve lash a number of times. The only thing I haven`t tried is running my engine in the opposite rotation (which is exactly what the one in the video by Dick from Ohio is doing) and I may yet try that.


----------



## /// (Dec 18, 2016)

Brian Rupnow said:


> The only thing I haven`t tried is running my engine in the opposite rotation (which is exactly what the one in the video by Dick from Ohio is doing) and I may yet try that.



Interesting observation!
You may also note that the video you linked to in post #3 is also running in that rotation.
Also, another video I found, which I think could probably be the best runner yet, rotates the same way:

[ame]https://www.youtube.com/watch?v=F_GUp5UXmxE&feature=youtu.be[/ame]

This one was built by HMEM member 'Weez'


----------



## Brian Rupnow (Dec 18, 2016)

So, after two weeks or more of screwing around with this engine, it seems I am back to about where I started. Excuse the oil splatters--that is actually WD40 sprayed on while running, hoping to free up anything which may have been in the least bit "sticky". The only trick I have left is to try setting the engine up to run in reverse rotation. I have no idea why that would make any difference, but in an effort to "leave no stone unturned" I will probably try that next. 
[ame]https://www.youtube.com/watch?v=7PsXe6_P5yo&feature=youtu.be[/ame]


----------



## gbritnell (Dec 18, 2016)

Brian,
In watching your last video if I had to guess what is going on I would say that your governor springs are too strong. The governor weights pop out just when the engine hits and on the next stroke or two they retract. 
Just my two cents worth.
gbritnell


----------



## Brian Rupnow (Dec 18, 2016)

gbritnell said:


> Brian,
> In watching your last video if I had to guess what is going on I would say that your governor springs are too strong. The governor weights pop out just when the engine hits and on the next stroke or two they retract.
> Just my two cents worth.
> gbritnell


You could be right George. I tried it with only one spring and it ran so slowly it would hardly keep going. I then shortened the one spring and it still ran very, very slowly. then I put the two springs back on.


----------



## Cogsy (Dec 19, 2016)

Brian - I was just out whippersnipping (weedeating I think you guys call it?) the jungle in the backyard as the dog was getting lost and the kangaroos were sneaking up and pinching the chook food, and I found myself thinking about your Kerzel. I seem to remember a video not so long ago (I think when you first got it out after not running for a long time) and if I remember correctly you had to fiddle with the fuel mixture a couple of times in about 1 minute to keep it going into hit and miss. I know these little carbs can be finicky but I'm thinking this one might be playing up. Especially if it runs really slowly with light governor springs - if it was getting a nice big hit it would spin the flywheels nice and fast then the light springs would keep it from hitting again til it had slowed right down. If you're only getting a small change in flywheel velocity it has to mean low power (I've almost convinced myself).

You've tried valve and ignition timing and compression is good (I think you said) so I'd suggest trying it with a known good carb from a similar sized engine to see if you can get more Oompf from each hit.


----------



## Brian Rupnow (Dec 19, 2016)

I do have one of my fabulous "Jag" carburetors here, which has a thru bore of 0.195" as compared to the .125" passage thru the existing Upshur carb currently on the engine, which has a thru bore of 0.125". That is an increase of 243% in cross sectional area. The threads on the jag carb are the same as the threads on the Upshur style carb. It won't cost me any money to switch out the carburetors, just a bit of time. If I can pump twice as much fuel/air mix into the combustion chamber I don't know what the net effect will be. The engine has an atmospheric intake valve and no forced air induction, so maybe nothing will change.--But then again-----


----------



## Brian Rupnow (Dec 19, 2016)

Now, THAT is a carburetor. The original carburetor, which was modelled after the Upshur carb is laying on the wood below the Jag carburetor.


----------



## Jyman (Dec 19, 2016)

Hey Brian, 

do you think the o-ring is making to much drag? If you hold the exhaust valve open and give the flywheels a spin with your hand does it make a couple revolutions, or does it lose it's momentum fast? 

Jonathan


----------



## Brian Rupnow (Dec 19, 2016)

Jyman said:


> Hey Brian,
> 
> do you think the o-ring is making to much drag? If you hold the exhaust valve open and give the flywheels a spin with your hand does it make a couple revolutions, or does it lose it's momentum fast?
> 
> Jonathan


If I hold a valve open and flip the flywheel with my hand I get 2 full rotations of crankshaft, maximum.


----------



## Jyman (Dec 20, 2016)

Brian Rupnow said:


> If I hold a valve open and flip the flywheel with my hand I get 2 full rotations of crankshaft, maximum.




Two full rotations that doesn't seem like a lot to me. That could be where the problem is, if the friction is lower it would free wheel longer. Which would mean that the miss part would take longer to slow down to go back into hit mode. Is there anything you can do to free up some friction to see if that would help?


----------



## Brian Rupnow (Dec 20, 2016)

Jyman said:


> Two full rotations that doesn't seem like a lot to me. That could be where the problem is, if the friction is lower it would free wheel longer. Which would mean that the miss part would take longer to slow down to go back into hit mode. Is there anything you can do to free up some friction to see if that would help?


In short---No, not really. It has ball bearings instead of bushings already.


----------



## Jyman (Dec 20, 2016)

What about replacing your o-ring with Teflon tape, the same stuff pipe fitters use on threaded connections. Just take a couple inches and spin it into a rope. It should glide smooth in the bore.  It might give you a chance to reduce some friction with out doing a lot of work to it. Even if the Teflon only holds up for 10 mins.


----------



## Brian Rupnow (Dec 21, 2016)

Tonight I had the Kerzel running quite elegantly with the larger carburetor on it, and the Kerzel lever removed. I was afraid that the carburetor might be too large for a 3/4" diameter single cylinder engine. As the barrel of the carburetor gets larger, the air flowing thru it slows down, and consequently doesn't create as much of a low pressure area (Venturi effect) in the area where the spray bar for the gasoline pokes into the air stream. Since the low pressure area becomes less, it won't lift gasoline from the tank nearly as well, and the engine starves for fuel. It is very cold outside, and I don't want to gas myself, so I didn't have the engine running for very long. It does seem to be working all right with the larger carb, and is responsive to the opening/closing of the throttle. I will do more testing as time allows, out in my main garage. Once I am convinced that the engine is okay with this larger carb, I will try out the hit and miss function again.


----------



## Brian Rupnow (Dec 21, 2016)

An interesting factoid--I just went back and had a look at the original Kerzel carburetor plans. Kerzel calls for a 3/16" thru hole in the carburetor with a 1/4" counterbore from both ends. For whatever reason, at the time I was unable to make this carburetor, but was able to make a carb from an old set of Upshur plans that I found on an internet site. The Upshur carburetor must have had a 1/8" thru hole because that is what I have measured on the carb I just replaced on the engine. I have always thought that my engine didn't hit as strongly as other Kerzel engines I have seen videos of on the net. It seems that the bore of my Jag carburetor is much closer to what Kerzel originally intended.


----------



## Brian Rupnow (Dec 23, 2016)

Awright!!--We're done here!! Not exactly what I was hoping for, but close enough for me. It does hit, it does miss, and it starts easy.
[ame]https://www.youtube.com/watch?v=swoSgioWTO8&feature=youtu.be[/ame]


----------



## ShopShoe (Dec 24, 2016)

Brian,

I knew you'd get it licked. I like the way it runs and sounds now.

It looks nice, too.

Not many of us like to revisit past projects after passage of time, no matter what we promise: You get the perseverence award for this one.

Gotta get me my ration of Rupnow postings to complete my day.

Thanks

--ShopShoe


----------



## Brian Rupnow (Dec 24, 2016)

Thank you Shopshoe. Other than what I can find on the internet, I live in kind of a vacuum here, as far as model engines go. I have very little to compare my stuff to after I have built it.--Brian


----------



## Jyman (Dec 27, 2016)

Brian, 

It's nice to see that you got it up and running, it's a very nice looking as well as very nice sounding engine. You should be proud. 

Jon


----------



## Brian Rupnow (Dec 27, 2016)

Jyman--I got the engine up and running 6 years ago, as can be seen in post #2 of this thread. All of the things I did over the last month was aimed at possibly getting a better hit and miss action. If you watch the very last video and then watch the video in post # 2, there really isn't a heck of a lot of difference.---Brian


----------



## Jyman (Dec 28, 2016)

Brian, 

I knew you had it up and running before, but taking it all apart and making changes and making it run better is something to be proud of.

Jon


----------

