Atkinson frustrations

[Ramoye]

Gordon,

Had some luck today. I adjusted as much as I could with the eccentric crank pin and used the 1 7/16 link arms. The engine actually ran on its own power. I had one 3 minute run and a couple of 2 minute runs, and several runs between 30 seconds and 1 minute. It was awesome to see it run! Still needs more break-in time for longer runs.

After a couple of cylinders, three different lengths of link arms, three sets of rings, two different front and back panels, steel prosthetic tips for broken oscillating arm ends, an eccentric crank pin, two different spark plugs, various fuel/oil mixtures, and a modified crankshaft, it finally ran.

Ray

 

[dsage]

Gordon / Ray:
I appreciate all of the research you guys are going through to figure out the problem with this engine. As I mentioned before, after I finished the 3D CAD model and found something "not right" about it I put it aside and never started the build. I've been playing around with the drawings while following your threads here. Even manipulating the drawings has been frustrating (although much less work I'm sure) and I've had no luck being satisfied that it looks like it would run.
It has been difficult to follow all of the changes you have made to the original design. When you finally get it running to your satisfaction would you be so kind as to detail only what changes need to be made to the drawings in the book to make it work? I'd appreciate it. Then I'll add it back into my "to be built" list. I've always liked this engine.


Thanks

 

[Gordon]

Gordon,

Had some luck today. I adjusted as much as I could with the eccentric crank pin and used the 1 7/16 link arms. The engine actually ran on its own power. I had one 3 minute run and a couple of 2 minute runs, and several runs between 30 seconds and 1 minute. It was awesome to see it run! Still needs more break-in time for longer runs.

After a couple of cylinders, three different lengths of link arms, three sets of rings, two different front and back panels, steel prosthetic tips for broken oscillating arm ends, an eccentric crank pin, two different spark plugs, various fuel/oil mixtures, and a modified crankshaft, it finally ran.

Ray

That is great. I got sidetracked on a couple of other projects so it will be a few days before I get back to the engine.

 

[Ramoye]

Gordon / Ray:
I appreciate all of the research you guys are going through to figure out the problem with this engine. As I mentioned before, after I finished the 3D CAD model and found something "not right" about it I put it aside and never started the build. I've been playing around with the drawings while following your threads here. Even manipulating the drawings has been frustrating (although much less work I'm sure) and I've had no luck being satisfied that it looks like it would run.
It has been difficult to follow all of the changes you have made to the original design. When you finally get it running to your satisfaction would you be so kind as to detail only what changes need to be made to the drawings in the book to make it work? I'd appreciate it. Then I'll add it back into my "to be built" list. I've always liked this engine.


Thanks

Dsage,
I think we are making progress, but still more to do. I will be happy to share what I have learned with others once I get it working consistently. This thing has been a challenge.
Ray

 

[Ramoye]

That is great. I got sidetracked on a couple of other projects so it will be a few days before I get back to the engine.

Gordon,

I ran the engine with assistance from the electric motor for about 1 1/2 hours, hoping to get a longer run under its own power. It did not run as well today as yesterday. The max run time (on its own power) I got out of it was 1 1/2 minutes, just barely turning. Some (more than usual) oil was dripping out the back of the left end of the cylinder. I suspect the top piston ring may be sticking. I had an issue with the sticking ring before and honed it some on a stone. May still need some more honing. I will pull it out and check it tomorrow.

I wish I could have gotten more adjustment from the eccentric crank pin, but was limited by the right oscillating arm going over center. I may make an eccentric pivot shaft for the right oscillating arm. This would allow me to adjust the pivot point of the right oscillating arm, thus giving me more adjustment with the eccentric crank pin for piston position. Before I go to this trouble, I will do some more break-in to see if I can get additional time running on its own power.

One problem I have is some misalignment with the right oscillating arm top brass bushing, causing some binding at a certain point during rotation. I may press the old bushing out and replace it with a new bushing. This misalignment could be just enough to limit the run time (marginal power to overcome the misalignment).

Thanks.

Ray

 

[Gordon]

Gordon,

I ran the engine with assistance from the electric motor for about 1 1/2 hours, hoping to get a longer run under its own power. It did not run as well today as yesterday. The max run time (on its own power) I got out of it was 1 1/2 minutes, just barely turning. Some (more than usual) oil was dripping out the back of the left end of the cylinder. I suspect the top piston ring may be sticking. I had an issue with the sticking ring before and honed it some on a stone. May still need some more honing. I will pull it out and check it tomorrow.

I wish I could have gotten more adjustment from the eccentric crank pin, but was limited by the right oscillating arm going over center. I may make an eccentric pivot shaft for the right oscillating arm. This would allow me to adjust the pivot point of the right oscillating arm, thus giving me more adjustment with the eccentric crank pin for piston position. Before I go to this trouble, I will do some more break-in to see if I can get additional time running on its own power.

One problem I have is some misalignment with the right oscillating arm top brass bushing, causing some binding at a certain point during rotation. I may press the old bushing out and replace it with a new bushing. This misalignment could be just enough to limit the run time (marginal power to overcome the misalignment).

Thanks.

Ray

Ray
Make sure that the oscillating arm or the connecting rod is not hitting on the bottom of the cylinder. I have had that problem. There is not much clearance.

 

[Ramoye]

Ray
Make sure that the oscillating arm or the connecting rod is not hitting on the bottom of the cylinder. I have had that problem. There is not much clearance.

Gordon,
I ran into that problem. I had to chamfer the piston rods for cylinder clearance, and had to use a shorter set screw on the right oscillating arm. Had problems with the set screws working lose, so applied some Locktite threadlocker (blue).
Thanks for the information.
Ray

 

[dsage]

Ray:
I don't want to state the obvious but the way you wrote it, it sounds like you were forcing the engine to run with a solidly connected electric starter motor. The electric motor must be connected with something like a one way clutch (or manually applied) so the engine can run at it's own speed (faster than the starter) once it decides to run. Basically I'm saying the starter motor and the engine cannot be solidly connected. It will never run that way. I questioned this before when you reported that the engine would not run but that it got very hot. Sounds to me like it was actually firing but being held back by the starter.
Excuse me if I've mis-interpreted your post(s).

 

[Ramoye]

Ray:
I don't want to state the obvious but the way you wrote it, it sounds like you were forcing the engine to run with a solidly connected electric starter motor. The electric motor must be connected with something like a one way clutch (or manually applied) so the engine can run at it's own speed (faster than the starter) once it decides to run. Basically I'm saying the starter motor and the engine cannot be solidly connected. It will never run that way. I questioned this before when you reported that the engine would not run but that it got very hot. Sounds to me like it was actually firing but being held back by the starter.
Excuse me if I've mis-interpreted your post(s).

Dsage,
I have wondered about that. I have a belt from the electric motor to the flywheel of the engine. Gingery did it this way in his book, but I know what you are saying about the coupling effect. I occasionally remove the belt and try cranking the engine by turning the flywheel. A clutch would be nice. I could make something and save my arm from trying to crank the motor. Today was a repeat of yesterday. The engine would run some on its own power (really get with it), then I would hear what sounded like a faint backfire or two, then the engine would wind down until it stopped. Not sure why. I tried playing with the ignition timing some. I will try again tomorrow.
Thanks.
Ray

 

[Gordon]

Gordon,
I ran into that problem. I had to chamfer the piston rods for cylinder clearance, and had to use a shorter set screw on the right oscillating arm. Had problems with the set screws working lose, so applied some Locktite threadlocker (blue).
Thanks for the information.
Ray

I added set screws on the top of each side of the connecting rod instead of at the bottom of the arm. That works much better.

I played around with the engine again a little bit on Saturday and I tried another RC carburetor which seemed to work much better. I actually got firing instead of backfiring. I am convinced that the problem is proper atomizing of the fuel mixture. It is constantly flooding. It seem to fire when you first start and then it quits and if you take out the spark plug the chamber is completely flooded. Clear it and it runs again for a short period until it floods again. I also have the problem with spitting back through the carburetor. I think that the problem may be that the intake valve is not seating properly. I am thinking a stronger spring on the intake and a weaker spring on the exhaust. It is always going to put pressure on the intake valve before the exhaust valve because it reaches the intake valve port on the power/exhaust stroke before the exhaust port is open. I will try some playing around with the springs.

I also tried a Jan Ridder vapor carburetor but that just spit fuel back through the vent hole because of the pressure at the intake port before it got to the exhaust port.

When I put the engine back together with the new cylinder and new rings I had good compression. After some running the compression is back down to about 15#.

Gordon

 

[dsage]

I also tried a Jan Ridder vapor carburetor but that just spit fuel back through the vent hole because of the pressure at the intake port before it got to the exhaust port.

If Sounds like your intake valve is defective. PRESSURE in the cylinder should be holding the intake valve closed and sealing it - spring or no spring. Also you'll want a fairly LIGHT intake spring so vacuum in the cylinder (on the intake stroke) can pull it open.

 

[Gordon]

If Sounds like your intake valve is defective. PRESSURE in the cylinder should be holding the intake valve closed and sealing it - spring or no spring. Also you'll want a fairly LIGHT intake spring so vacuum in the cylinder (on the intake stroke) can pull it open.

Due to the design the valve would be held open without a spring due to gravity. It is vertical head down. Perhaps it should have been mounted head up but it is too late for that. I have tried lapping it and it seals but apparently not well enough.

 

[dsage]

Understood. What I was trying to emphasize is that ANY intake valve should be held closed sufficiently to seal by air pressure. Only minimal spring pressure is required especially on an atmospheric intake engine. (in this case enough to overcome gravity plus a bit to seal).
Maybe try a bit of air pressure on the exhaust port. You'll need to make some sort of good sealing hose adapter to the exhaust port. Hold the exhaust valve open (it should be forced open by pressure anyway). Remove the spark plug. Apply pressure then see where you have leaks. If you hear air from the carb you have intake valve leak. If you hear it from the cylinder (open end and spark plug end) you have ring leak.

Keep at it. Thanks

 

[Ramoye]

I added set screws on the top of each side of the connecting rod instead of at the bottom of the arm. That works much better.

I played around with the engine again a little bit on Saturday and I tried another RC carburetor which seemed to work much better. I actually got firing instead of backfiring. I am convinced that the problem is proper atomizing of the fuel mixture. It is constantly flooding. It seem to fire when you first start and then it quits and if you take out the spark plug the chamber is completely flooded. Clear it and it runs again for a short period until it floods again. I also have the problem with spitting back through the carburetor. I think that the problem may be that the intake valve is not seating properly. I am thinking a stronger spring on the intake and a weaker spring on the exhaust. It is always going to put pressure on the intake valve before the exhaust valve because it reaches the intake valve port on the power/exhaust stroke before the exhaust port is open. I will try some playing around with the springs.

I also tried a Jan Ridder vapor carburetor but that just spit fuel back through the vent hole because of the pressure at the intake port before it got to the exhaust port.

When I put the engine back together with the new cylinder and new rings I had good compression. After some running the compression is back down to about 15#.

Gordon

Hi Gordon,
I believe you are right about the intake. I also have problems with plug fouling with too rich a mixture. Constantly cleaning the spark plug. Have not had much luck like I did the other day. It will turn over and occasionally run for a few seconds.

I have been experimenting today with an eccentric oscillating arm shaft on the right side to change the pivot point, but no real change in performance yet. Seems to be getting good firing when running with the electric motor, but only runs a little under its own power. Frequent plug fowling. When it does run a little, it acts like fuel starvation then quits. My carb. is really crude and that may be part of the problem. I need to take some time to correct my linkage misalignment, it is causing friction at certain points of the rotation. If the engine had enough power, the little friction should not be an issue, but this thing is very marginal on the power. My compression is running close to what you are measuring, maybe a couple of pounds less.

 

[Ramoye]

I added set screws on the top of each side of the connecting rod instead of at the bottom of the arm. That works much better.

I played around with the engine again a little bit on Saturday and I tried another RC carburetor which seemed to work much better. I actually got firing instead of backfiring. I am convinced that the problem is proper atomizing of the fuel mixture. It is constantly flooding. It seem to fire when you first start and then it quits and if you take out the spark plug the chamber is completely flooded. Clear it and it runs again for a short period until it floods again. I also have the problem with spitting back through the carburetor. I think that the problem may be that the intake valve is not seating properly. I am thinking a stronger spring on the intake and a weaker spring on the exhaust. It is always going to put pressure on the intake valve before the exhaust valve because it reaches the intake valve port on the power/exhaust stroke before the exhaust port is open. I will try some playing around with the springs.

I also tried a Jan Ridder vapor carburetor but that just spit fuel back through the vent hole because of the pressure at the intake port before it got to the exhaust port.

When I put the engine back together with the new cylinder and new rings I had good compression. After some running the compression is back down to about 15#.

Gordon

Hi Gordon,

Hope you had a great Thanksgiving.

I was able to get four 10 minute runs on the engine today on its own power. Seems to be getting better every day. Still getting plug fouling, and when it does quit it, is after hearing what sounds like some backfiring. To start the engine, it requires a squirt of heavy oil into the carb. and choking it until it starts running. I lengthened the venturi on the carb, which seemed to help some. I ordered a Poulan chainsaw carb. to try out. I will have to make an adapter to go from the Poulan carb to the engine intake. It will be several weeks before I get the new carb. (coming from Hong Kong, cost 6 bucks). Meanwhile, I will keep running the engine to see if I get even more improvement.

I fixed my misalignment issue with the right oscillating arm by replacing the bronze bushing. Unfortunately, the oscillating arm casting cracked when I pressed the new bushing in, requiring me to braze the crack (never performed aluminum brazing before, so I learned something).

How things going on your end?

Ray

 

[Gordon]

Hi Gordon,

Hope you had a great Thanksgiving.

I was able to get four 10 minute runs on the engine today on its own power. Seems to be getting better every day. Still getting plug fouling, and when it does quit it, is after hearing what sounds like some backfiring. To start the engine, it requires a squirt of heavy oil into the carb. and choking it until it starts running. I lengthened the venturi on the carb, which seemed to help some. I ordered a Poulan chainsaw carb. to try out. I will have to make an adapter to go from the Poulan carb to the engine intake. It will be several weeks before I get the new carb. (coming from Hong Kong, cost 6 bucks). Meanwhile, I will keep running the engine to see if I get even more improvement.

I fixed my misalignment issue with the right oscillating arm by replacing the bronze bushing. Unfortunately, the oscillating arm casting cracked when I pressed the new bushing in, requiring me to braze the crack (never performed aluminum brazing before, so I learned something).

How things going on your end?

Ray

Ray: Still not much progress but I have been mostly sidetracked the last week or so. I find it interesting that you refer to backfiring because that seems to be what I get most of the time, Only once did I have a run with the electric motor where I thought that the engine was firing instead of backfiring. After running a few minutes with the electric motor if I remove the spark plug it is completely soaked in fuel or oil and not too likely to run. I have been using Coleman fuel with just a little Marvel Mystery oil. I think that the carburetor is a big part of the problem. It is interesting because the Gingery plans show a very simple carburetor. I have been using a carburetor I had. Perhaps I should take another look at the Gingery carburetor.

I do not know about the Poulan carb but I would thing that it is probably too big. The problem seems to be too much fuel, not too little.

Gordon

 

[Ramoye]

Ray: Still not much progress but I have been mostly sidetracked the last week or so. I find it interesting that you refer to backfiring because that seems to be what I get most of the time, Only once did I have a run with the electric motor where I thought that the engine was firing instead of backfiring. After running a few minutes with the electric motor if I remove the spark plug it is completely soaked in fuel or oil and not too likely to run. I have been using Coleman fuel with just a little Marvel Mystery oil. I think that the carburetor is a big part of the problem. It is interesting because the Gingery plans show a very simple carburetor. I have been using a carburetor I had. Perhaps I should take another look at the Gingery carburetor.

I do not know about the Poulan carb but I would thing that it is probably too big. The problem seems to be too much fuel, not too little.

Gordon

Hi Gordon,

I agree that the carb is a big part of the problem, too much liquid fuel getting into the cylinder (not getting enough atomization). It helped some by extending the venturi to get the jet and needle closer to the low pressure area. The jet and needle really should align with the choke area of the venturi for lowest pressure point. I think the backfiring is coming when the plug gets saturated in liquid gas, delaying the combustion.

I don't know if the Walbro chainsaw carb. is too big, it may be. The carb is self regulating, so it may just take what fuel it needs based on the engine vacuum. It has both a low speed and high speed adjustment, so may be able to control the fuel intake some. For six bucks, worth a try. Not sure how the combination of pressure pulse and vacuum will affect the carb. performance, guess I will find out?

I had a 29 minute run today with the engine running on its own power. Then I had a 6 minute run. Plug was fouling, but cylinder temp. may have been affecting it some too (was getting hot). I have a small 12V fan I plan on incorporating at some point to help keep the cylinder cool. I am using two 1 1/2 link arms and the Gingery carb. with an extended venturi. I am having to squirt some heavy oil in the carb. to get the engine to start running. I am using aviation gas with some 2 cycle oil mixed in.

Good luck Gordon.

Ray

 

[dsage]

Have you guys considered propane? Sometimes (that's Sometimes with a BIG S) you can just hook propane up to the carb where the gasoline normally connects. BUT of course you'll need a regulator. I've used a barbeque regulator thus: (Plumbing torch tank with shutoff - brass fittings to the barbecue regulator input - hose from regulator output to engine). The barbecue regulator only puts out ounces (or less) of pressure so your carb needle will control it. The caveat is whether your needle is large enough because normally you need much more propane than gasoline. But it sounds like you are getting too much gasoline now so it might be ok as is. My Parcell and Weed engine does not have a carb or needle valve. Propane flows directly into the intake valve. It was meant to run on lamp gas back in 1902. So for this engine I added an additional homemade needle valve between the regulator and the engine to control the free flow. As mentioned your needle valve might be ok as is.
Parcell and Weed engine here:
http://davesage.ca/parcell and weed.html

 

[Ramoye]

Ray: Still not much progress but I have been mostly sidetracked the last week or so. I find it interesting that you refer to backfiring because that seems to be what I get most of the time, Only once did I have a run with the electric motor where I thought that the engine was firing instead of backfiring. After running a few minutes with the electric motor if I remove the spark plug it is completely soaked in fuel or oil and not too likely to run. I have been using Coleman fuel with just a little Marvel Mystery oil. I think that the carburetor is a big part of the problem. It is interesting because the Gingery plans show a very simple carburetor. I have been using a carburetor I had. Perhaps I should take another look at the Gingery carburetor.

I do not know about the Poulan carb but I would thing that it is probably too big. The problem seems to be too much fuel, not too little.

Gordon

Gordon,

The engine is starting to run consistent for a few minutes if I squirt heavy oil into the carb. My theory is that the oil is doing two things. 1) There is some leakage on the left piston when the piston is all the way back on the left side. The oil is helping to seal it. When the piston moves to the right just a little, it completely seals and holds 90 psi. I attribute this to a side load on the piston at the far left position. I believe the left oscillating arm to piston rod connection needs to go down a little to eliminate the piston side load (move oscillating pivot point down may be the solution). Also, moving the cylinder to the left may help, but changes port location relative to the cylinders. 2) The oil is helping to regulate the fuel intake, until the gas washes it away, allowing gas flooding of the engine. A new carb. might eliminate this problem (has better gas regulation). Could be the fuel jet diameter is too big in the Gingery carb., and the oil compensates for it by partially blocking some of the fuel. It seems carb. settings change on any given day (may be due to atmospheric changes).

I got a 13 minute run on the engine. Mostly though, I got a lot of 3 to 5 minute runs, repeatable with a squirt of heavy oil into the carb. Plug fouls often, but looks like gas fouling, not seeing much heavy oil in the plug (I believe the heavy oil is burning off, because I see smoke exiting the exhaust muffler).

Ray

 

[dsage]

Another thought on the propane. If you find it works and your happy with it you will need to build a "demand" regulator because, as I think more about it, propane will free flow out of your carb air intake when the engine is not running. A demand regulator will supply propane only when the engine "sucks" air in (like it does for gasoline from a tank below the carb).
So to test the engine on propane initially you should probably turn the engine over and then slowly supply the propane with the needle until it runs and shut the propane off at the tank to stop the engine.