Tuning OS .35
03-09-2005 | 08:56 PM
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From: , BC, CANADA
Tuning OS .35
Hello all... ( i know it's an old engine) but I was wondering if anyone could help in tuning this OS .35 Engine? I am having a hell of a time keeping this engine running. It starts very easily and runs at a nice idle, but after about a minute it will die. Then i spin it again and it fires up right away without any delay. I believe i have the mixture setting dialed in fairly well. If i leave the Glow Igniter on the engine will continue to run without any problems. (it has new fuel and plug)
If anyone has some tips or ideas i would greatly appreciate it!!
THanks,
Pete
If anyone has some tips or ideas i would greatly appreciate it!!
THanks,
Pete
03-09-2005 | 09:58 PM
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From: , BC, CANADA
RE: Tuning OS .35
i'm using #8... when i remove the igniter from the engine it stays running at the same RPM and then after about 30secs or so it just dies. the plug is brand new!
thanks,
pete
thanks,
pete
03-09-2005 | 11:43 PM
#4
My Feedback: (16)
RE: Tuning OS .35
That engine was real popular in the very late 60's and early 70's. I had a half dozen or so.
It has a air bleed type carb.
The idle air bleed screw is on the right front of the carb when standing behind the engine.
To screw it in, the mixture gets richer with fuel. And vice versa.
If you get lost as to where it's at. There is a little hole on the very front of the carb that this screw covered half way up when the engine was new.
A minute is a long time for one of these to idle.
Maybe you should try a idle bar plug in this old loop scavenged engine? That's what they ran in them back in the old days.
Enjoy,
Jim
It has a air bleed type carb.
The idle air bleed screw is on the right front of the carb when standing behind the engine.
To screw it in, the mixture gets richer with fuel. And vice versa.
If you get lost as to where it's at. There is a little hole on the very front of the carb that this screw covered half way up when the engine was new.
A minute is a long time for one of these to idle.
Maybe you should try a idle bar plug in this old loop scavenged engine? That's what they ran in them back in the old days.
Enjoy,
Jim
03-10-2005 | 01:33 AM
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From: , BC, CANADA
RE: Tuning OS .35
ahhhh... thanks Jim....
yes indeed it has that screw on the right side of the carb. so what does the needle do if this screw controls the mixture? i am lost on where it should be set at.?? i'm not sure i follow you on your description of resetting it.
what the heck is an idel bar plug? so these things weren't meant to idle for very long?
thanks for your imput Jim, you've already explained a lot so far. This engine came in an old Buzzard Bombshell 72" damaged plane. Will it be ok for this?
here is another view of the carb.
pete
yes indeed it has that screw on the right side of the carb. so what does the needle do if this screw controls the mixture? i am lost on where it should be set at.?? i'm not sure i follow you on your description of resetting it.
what the heck is an idel bar plug? so these things weren't meant to idle for very long?
thanks for your imput Jim, you've already explained a lot so far. This engine came in an old Buzzard Bombshell 72" damaged plane. Will it be ok for this?
here is another view of the carb.
pete
03-10-2005 | 08:49 AM
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RE: Tuning OS .35
ORIGINAL: swixtt
ahhhh... thanks Jim....
yes indeed it has that screw on the right side of the carb. so what does the needle do if this screw controls the mixture?
>That screw limits how far the barrel inside the carb will open/close.
>It should be adjusted so that it allows the barrel to fully open, but
>when you close it (reduce the engine to idle ) it should be just a
>little beyond where the hole in the barrel disappears.
i am lost on where it should be set at.?? i'm not sure i follow you on your description of resetting it.
what the heck is an idel bar plug? so these things weren't meant to idle for very long?
>An idle bar glow plug has a bar that goes across the opening where
>the heating element is. The older engines often loaded up on fuel
>and the fuel would cool down/shut down the heating element so the
>glow plug would not ignite the fuel. The idle bar prevented/minimized
>the raw fuel from cooling the heating element off. Tower has idle
>bar glo plugs.
>
>The early RC engines were basically converted U/C engines. U/C
>engines were designed to run wide open. Your engine will idle,
>but not as smoothly as the newer engines. The porting in the
>engine makes a great deal of difference. I have an old Webra 61
>that requires an idle bar plug. The engine runs great, just the idle
>needs to be set a little higher to allow it to run smoothly. My
>Webra idles at about 2,100 rpms, where my other engines will
>idle reliably at about 1,800 - 1,900 rpms.
thanks for your imput Jim, you've already explained a lot so far. This engine came in an old Buzzard Bombshell 72" damaged plane. Will it be ok for this?
here is another view of the carb.
pete
ahhhh... thanks Jim....
yes indeed it has that screw on the right side of the carb. so what does the needle do if this screw controls the mixture?
>That screw limits how far the barrel inside the carb will open/close.
>It should be adjusted so that it allows the barrel to fully open, but
>when you close it (reduce the engine to idle ) it should be just a
>little beyond where the hole in the barrel disappears.
i am lost on where it should be set at.?? i'm not sure i follow you on your description of resetting it.
what the heck is an idel bar plug? so these things weren't meant to idle for very long?
>An idle bar glow plug has a bar that goes across the opening where
>the heating element is. The older engines often loaded up on fuel
>and the fuel would cool down/shut down the heating element so the
>glow plug would not ignite the fuel. The idle bar prevented/minimized
>the raw fuel from cooling the heating element off. Tower has idle
>bar glo plugs.
>
>The early RC engines were basically converted U/C engines. U/C
>engines were designed to run wide open. Your engine will idle,
>but not as smoothly as the newer engines. The porting in the
>engine makes a great deal of difference. I have an old Webra 61
>that requires an idle bar plug. The engine runs great, just the idle
>needs to be set a little higher to allow it to run smoothly. My
>Webra idles at about 2,100 rpms, where my other engines will
>idle reliably at about 1,800 - 1,900 rpms.
thanks for your imput Jim, you've already explained a lot so far. This engine came in an old Buzzard Bombshell 72" damaged plane. Will it be ok for this?
here is another view of the carb.
pete
03-10-2005 | 10:22 AM
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From: , BC, CANADA
RE: Tuning OS .35
So Jim...
are we talking about the same screw? i have 2 on this carb... plus the needle. The screw on the top allows for adjustment of the barrel so i can control the idle. (and yes i had to keep it pretty high as well). The needle allows me to control the mixture... and the screw on the other side contols the barrel at 'high speed' or when the barrel is wide open?
i will have to investigate your suggestions about the glo plug and see if i can find one of those?? i am going to dig up the original and see if in fact it is a idle bar plug??
thanks again,
pete
are we talking about the same screw? i have 2 on this carb... plus the needle. The screw on the top allows for adjustment of the barrel so i can control the idle. (and yes i had to keep it pretty high as well). The needle allows me to control the mixture... and the screw on the other side contols the barrel at 'high speed' or when the barrel is wide open?
i will have to investigate your suggestions about the glo plug and see if i can find one of those?? i am going to dig up the original and see if in fact it is a idle bar plug??
thanks again,
pete
03-10-2005 | 12:35 PM
#8
RE: Tuning OS .35
Hi!
Ofcourse your OS .35 can idle for more a minute without problem...! It should be able to idle fine for 5-10 minutes or more and roar to life when you give full trottle.
Have you check the fuelneedle for dirt???
A starting point for the highspeed needle is 2 turns open.
The screw that controls the hole opening at the front of the carb is the idle screw.
The third screw you speak of is the screw pointing straight up and that screw is the screw that holds the throttle drum in place.
The idle screw or low speed needle controls the amount of air coming into the engine at idle/low speed (when the throttle drum is at idle/low speed and only then).
This idle screw should be set so the round opening at the front of the carb is half open.This is the starting point and can of course be changed. More open means more air is coming into the engine. More closed means less air, which also means that the engine runs richer at low speed.
Here it is vital that you know HOW your engine sounds and reacts when you set the idle.
If the engine hesitates and nearly dies when you give full power, then the idle mixture is too lean, if on the other hand the engine hesitates and bluddersand sputters fuel..then the idle needle is set too rich. Remember...there is also some interaction between the highspeed and low sped needle.
Regards!
Jan K
Sweden
Ofcourse your OS .35 can idle for more a minute without problem...! It should be able to idle fine for 5-10 minutes or more and roar to life when you give full trottle.
Have you check the fuelneedle for dirt???
A starting point for the highspeed needle is 2 turns open.
The screw that controls the hole opening at the front of the carb is the idle screw.
The third screw you speak of is the screw pointing straight up and that screw is the screw that holds the throttle drum in place.
The idle screw or low speed needle controls the amount of air coming into the engine at idle/low speed (when the throttle drum is at idle/low speed and only then).
This idle screw should be set so the round opening at the front of the carb is half open.This is the starting point and can of course be changed. More open means more air is coming into the engine. More closed means less air, which also means that the engine runs richer at low speed.
Here it is vital that you know HOW your engine sounds and reacts when you set the idle.
If the engine hesitates and nearly dies when you give full power, then the idle mixture is too lean, if on the other hand the engine hesitates and bluddersand sputters fuel..then the idle needle is set too rich. Remember...there is also some interaction between the highspeed and low sped needle.
Regards!
Jan K
Sweden
03-10-2005 | 03:10 PM
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From: Ludington,
MI
RE: Tuning OS .35
My 2 cents. I have several old max's and they all like idle bar plugs and they will not idle without one. Fox makes an idle bar plug. My money is on the plug.
