Walker machine 4.2
10-17-2010, 01:37 PM
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Walker machine 4.2
Hi Guys I'm new to gas engines. I have a zirolli Texan With a Walker Machine 4.2 in it. my problem is it just seems that it does not have alot of power. It likes to surge at full throttle it have replaced the plug. Tried different to cycle oils at 32-1. It has a C-H ignition in it. as far as timing goes I have no idea how to adjust it. I am swinging a 22-8. Does any one know about these engines? is it worth having? or do I just need to get a G62?
10-17-2010, 01:46 PM
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RE: Walker machine 4.2
First off the prop is too small, get a 24-8 or 10....
The Waller 4.2 is the best of the Sachs conversions and will outlat anything you put it on...
Get a carb diaphragm rebuild kit and have someone check the timing..Look for rpm in the 7000 range without the muffler, less with one...
The Waller 4.2 is the best of the Sachs conversions and will outlat anything you put it on...
Get a carb diaphragm rebuild kit and have someone check the timing..Look for rpm in the 7000 range without the muffler, less with one...
10-17-2010, 01:59 PM
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RE: Walker machine 4.2
Ok Thanks! I'll try the larger prop. But I dont have any one around that knows about the timing. And what would be the best oil to use and at what mixture?
10-17-2010, 02:23 PM
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RE: Walker machine 4.2
+It wa s chaninsaw...Go to Wally World and get a six pack of chainsaw oil, 3.2 oz to a gallon of regular gas....
Timing is easy to check...
turn on the igintiion with the spark plug out and resting on the cylinder slowly turn the crank CCW..When you hear the spark make a pencil line across the hub and crankcase..
Turn igninon off...Measure the diameter of the hub at the pencil line...Multiply by .244...Put the piston at TDC...Measure the distance between the two pencil lines,, it should be the same as you got with the .244 multiplication....If not move the sensor until it is...If there is linkage between the carb and sensor the carb needs to be completely closed when making the adjustment...If not you have a syncro spark, timing is automatic...
Timing is easy to check...
turn on the igintiion with the spark plug out and resting on the cylinder slowly turn the crank CCW..When you hear the spark make a pencil line across the hub and crankcase..
Turn igninon off...Measure the diameter of the hub at the pencil line...Multiply by .244...Put the piston at TDC...Measure the distance between the two pencil lines,, it should be the same as you got with the .244 multiplication....If not move the sensor until it is...If there is linkage between the carb and sensor the carb needs to be completely closed when making the adjustment...If not you have a syncro spark, timing is automatic...
10-17-2010, 02:48 PM
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RE: Walker machine 4.2
Ok Thanks! Will the timing being off cause the surging? I bought the airplane off my local hobby shop he built the plane 16 years ago. He only flew it a couple of times. and it was hanging in his shop for years until I bought it. Should I replumb the gas tank. Could this cause a problem?
10-17-2010, 03:44 PM
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RE: Walker machine 4.2
You will have to get the carb number, all kits are carb specific....
There could be 2 choices, Tillotson or Walbro...Most likely is a Walbro SDC 80 carb, the kit is D10 SDC. About $5 at a small engine shop...
There could be 2 choices, Tillotson or Walbro...Most likely is a Walbro SDC 80 carb, the kit is D10 SDC. About $5 at a small engine shop...
10-18-2010, 12:45 AM
#9
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RE: Walker machine 4.2
ORIGINAL: Antique
First off the prop is too small, get a 24-8 or 10....
The Waller 4.2 is the best of the Sachs conversions and will outlat anything you put it on...
Get a carb diaphragm rebuild kit and have someone check the timing..Look for rpm in the 7000 range without the muffler, less with one...
First off the prop is too small, get a 24-8 or 10....
The Waller 4.2 is the best of the Sachs conversions and will outlat anything you put it on...
Get a carb diaphragm rebuild kit and have someone check the timing..Look for rpm in the 7000 range without the muffler, less with one...
BC
10-18-2010, 02:20 PM
#10
RE: Walker machine 4.2
Hi Ryandl1
I'm the guy that worked at Walker Machine making the Walker Sachs. As for the carburetor issue I think I know what the problem is. Some of the Walker 4.2 engines used carburetors that had governors in them. Most airplane/engine combinations did not ever have any problems with this particular carburetor. Once in a great while the airframe engine combo would resonate at just the right frequency to unseat the governor which would allow more fuel into the engine and hence slow it down. The engine would run fine on the ground but , once in the air and the engine unloaded, the engine would go "rich" and no amount of needle valve adjustment would make the engine run right. The carburetor was used initially because it was the same one Sachs-Dolmar use on the 4.2 in their saws.
A 22 X 8 prop is undersize for the 4.2 engine. 24 x 10 what was normally used on a 4.2 .
I watch these threads from time to time to try and help those who have Walker engines. Some parts may still be available thru Precision Eagle (If they're still around?)as they had bought out the Walker Sachs line when we closed. The Walkers were renamed Precision Eaglets.
BCCHI, I'm sorry to hear about you closing shop. I hope you are able to recover from your medical challenge. Thank you very much for all your help when we were developing The Walker Sachs Engines.
Our Thoughts and Prayers are with you Bill,
Carlos G.
I'm the guy that worked at Walker Machine making the Walker Sachs. As for the carburetor issue I think I know what the problem is. Some of the Walker 4.2 engines used carburetors that had governors in them. Most airplane/engine combinations did not ever have any problems with this particular carburetor. Once in a great while the airframe engine combo would resonate at just the right frequency to unseat the governor which would allow more fuel into the engine and hence slow it down. The engine would run fine on the ground but , once in the air and the engine unloaded, the engine would go "rich" and no amount of needle valve adjustment would make the engine run right. The carburetor was used initially because it was the same one Sachs-Dolmar use on the 4.2 in their saws.
A 22 X 8 prop is undersize for the 4.2 engine. 24 x 10 what was normally used on a 4.2 .
I watch these threads from time to time to try and help those who have Walker engines. Some parts may still be available thru Precision Eagle (If they're still around?)as they had bought out the Walker Sachs line when we closed. The Walkers were renamed Precision Eaglets.
BCCHI, I'm sorry to hear about you closing shop. I hope you are able to recover from your medical challenge. Thank you very much for all your help when we were developing The Walker Sachs Engines.
Our Thoughts and Prayers are with you Bill,
Carlos G.
10-18-2010, 05:09 PM
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RE: Walker machine 4.2
I'm getting ready to go to work now so when I get home in the morning I'll take it off and see what I can find out. Thanks for all your help!
10-18-2010, 11:16 PM
#18
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RE: Walker machine 4.2
ORIGINAL: Carlos G
Hi Ryandl1
I'm the guy that worked at Walker Machine making the Walker Sachs. As for the carburetor issue I think I know what the problem is. Some of the Walker 4.2 engines used carburetors that had governors in them. Most airplane/engine combinations did not ever have any problems with this particular carburetor. Once in a great while the airframe engine combo would resonate at just the right frequency to unseat the governor which would allow more fuel into the engine and hence slow it down. The engine would run fine on the ground but , once in the air and the engine unloaded, the engine would go ''rich'' and no amount of needle valve adjustment would make the engine run right. The carburetor was used initially because it was the same one Sachs-Dolmar use on the 4.2 in their saws.
A 22 X 8 prop is undersize for the 4.2 engine. 24 x 10 what was normally used on a 4.2 .
I watch these threads from time to time to try and help those who have Walker engines. Some parts may still be available thru Precision Eagle (If they're still around?)as they had bought out the Walker Sachs line when we closed. The Walkers were renamed Precision Eaglets.
BCCHI, I'm sorry to hear about you closing shop. I hope you are able to recover from your medical challenge. Thank you very much for all your help when we were developing The Walker Sachs Engines.
Our Thoughts and Prayers are with you Bill,
Carlos G.
Hi Ryandl1
I'm the guy that worked at Walker Machine making the Walker Sachs. As for the carburetor issue I think I know what the problem is. Some of the Walker 4.2 engines used carburetors that had governors in them. Most airplane/engine combinations did not ever have any problems with this particular carburetor. Once in a great while the airframe engine combo would resonate at just the right frequency to unseat the governor which would allow more fuel into the engine and hence slow it down. The engine would run fine on the ground but , once in the air and the engine unloaded, the engine would go ''rich'' and no amount of needle valve adjustment would make the engine run right. The carburetor was used initially because it was the same one Sachs-Dolmar use on the 4.2 in their saws.
A 22 X 8 prop is undersize for the 4.2 engine. 24 x 10 what was normally used on a 4.2 .
I watch these threads from time to time to try and help those who have Walker engines. Some parts may still be available thru Precision Eagle (If they're still around?)as they had bought out the Walker Sachs line when we closed. The Walkers were renamed Precision Eaglets.
BCCHI, I'm sorry to hear about you closing shop. I hope you are able to recover from your medical challenge. Thank you very much for all your help when we were developing The Walker Sachs Engines.
Our Thoughts and Prayers are with you Bill,
Carlos G.
I am getting stronger and the only time I have pain is when I am awake,breathe of cough.My ribs have all came loose in front do not no what they can do about that maybe put in some carbon fibre.
BCCHI
08-08-2020, 11:28 AM
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Hi Ryandl1
I'm the guy that worked at Walker Machine making the Walker Sachs. As for the carburetor issue I think I know what the problem is. Some of the Walker 4.2 engines used carburetors that had governors in them. Most airplane/engine combinations did not ever have any problems with this particular carburetor. Once in a great while the airframe engine combo would resonate at just the right frequency to unseat the governor which would allow more fuel into the engine and hence slow it down. The engine would run fine on the ground but , once in the air and the engine unloaded, the engine would go "rich" and no amount of needle valve adjustment would make the engine run right. The carburetor was used initially because it was the same one Sachs-Dolmar use on the 4.2 in their saws.
A 22 X 8 prop is undersize for the 4.2 engine. 24 x 10 what was normally used on a 4.2 .
I watch these threads from time to time to try and help those who have Walker engines. Some parts may still be available thru Precision Eagle (If they're still around?)as they had bought out the Walker Sachs line when we closed. The Walkers were renamed Precision Eaglets.
BCCHI, I'm sorry to hear about you closing shop. I hope you are able to recover from your medical challenge. Thank you very much for all your help when we were developing The Walker Sachs Engines.
Our Thoughts and Prayers are with you Bill,
Carlos G.
I'm the guy that worked at Walker Machine making the Walker Sachs. As for the carburetor issue I think I know what the problem is. Some of the Walker 4.2 engines used carburetors that had governors in them. Most airplane/engine combinations did not ever have any problems with this particular carburetor. Once in a great while the airframe engine combo would resonate at just the right frequency to unseat the governor which would allow more fuel into the engine and hence slow it down. The engine would run fine on the ground but , once in the air and the engine unloaded, the engine would go "rich" and no amount of needle valve adjustment would make the engine run right. The carburetor was used initially because it was the same one Sachs-Dolmar use on the 4.2 in their saws.
A 22 X 8 prop is undersize for the 4.2 engine. 24 x 10 what was normally used on a 4.2 .
I watch these threads from time to time to try and help those who have Walker engines. Some parts may still be available thru Precision Eagle (If they're still around?)as they had bought out the Walker Sachs line when we closed. The Walkers were renamed Precision Eaglets.
BCCHI, I'm sorry to hear about you closing shop. I hope you are able to recover from your medical challenge. Thank you very much for all your help when we were developing The Walker Sachs Engines.
Our Thoughts and Prayers are with you Bill,
Carlos G.
Hoping you have a solution, Thanks, Ron.
08-08-2020, 06:27 PM
#20
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So I have one of these on a laser that does exactly what you describe here. Runs fine on the ground, goes rich in the air. I've been trying to find an answer to this problem since I've owned it. (about two years) So you know what the problem, how do I fix it?
Hoping you have a solution, Thanks, Ron.
Hoping you have a solution, Thanks, Ron.
08-10-2020, 07:59 AM
#21
I would do exactly as Truckracer has described regarding adding a static vent tube to the diaghram plate. On some planes that also develop pressure in the fuselage it may also be necessary to increase the pop off pressure in the carb by going with a stronger spring under the fulcrum lever. You could also stretch the existing spring a little to see it improves the issue .
08-17-2020, 03:01 PM
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I guess my previous reply did not get posted, so I'll try again, with a few pics to show the setup. I added the velocity stack to see if it would take care of air across the carb., it made no change, but maybe it would not do what is needed. I have also stretched the spring on the needle valve quite a bit, again no change. I was hoping there would be a way to kill governor, if the carb. really has that. Or maybe find a carb. that would work for a replacement. I would really like to fly this thing, but I'm not going to dead stick it in every time. Any help is appreciated. Ron.
P.S. The screw left of the fuel inlet, I've never seen that on a carb, before.
P.S. The screw left of the fuel inlet, I've never seen that on a carb, before.
08-17-2020, 03:47 PM
#24
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What model carb are you running. Most likely a Walbro and if so, what model number is stamped on the side of the carb? The most common carb I've seen on the Sachs based 4.2 is the Walbro SDC80 but some Tillotson carbs were also used in those days.If an SDC 80, the letters SDC will be cast in one of the diaphragm cover plates.