nitro engines
11-21-2011, 05:48 PM
#2
RE: nitro engines
There are actually 3 lengths of plugs. The left side plug below is a short reach and it's generally only needed in some very small engines. The centre plug is a medium reach and these are only made by OS and Enya although no one has any explanation as to why both these Japanese manufacturers went for that length other than they'll fit all sizes of their engines. The right side is a long plug, obviously 
). Ideally, the correct length plug to use is the one that ends up being flush with the combustion chamber. Instruction sheets usually say what length to use but if in doubt it's just a matter of taking off the head and screwing a plug in to see what fits best.
Ah OK, I can't help adding that there's no such thing as a "nitro" engine. They're called "glow" engines. I have maybe a hundred engines but I don't use nitro in the fuel so I can't possibly have any "nitro" engines .
). Ideally, the correct length plug to use is the one that ends up being flush with the combustion chamber. Instruction sheets usually say what length to use but if in doubt it's just a matter of taking off the head and screwing a plug in to see what fits best.Ah OK, I can't help adding that there's no such thing as a "nitro" engine
. They're called "glow" engines. I have maybe a hundred engines but I don't use nitro in the fuel so I can't possibly have any "nitro" engines .
11-22-2011, 10:07 AM
#3
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RE: nitro engines
Adding to Downunder's always excellent posts...
Long plugs have a tendancy of holding heat better, so they tend to be used on 4 stroke engines, since the engines fires less frequently.
In a two stroke engine a long plug can upset the ignition of fuel...
However long plugs can also be used to cure minor engine problems... e.g. they may protrude slightly into the compression area, which can help with an inverted engine situation, by keeping the glow element lit longer when fuel flows into the inverted head.
They can also help keep the engine running when the engine is running too rich for whatever reason.... but you are best advised to tune the engine properly in this situation.
Long plugs have a tendancy of holding heat better, so they tend to be used on 4 stroke engines, since the engines fires less frequently.
In a two stroke engine a long plug can upset the ignition of fuel...
However long plugs can also be used to cure minor engine problems... e.g. they may protrude slightly into the compression area, which can help with an inverted engine situation, by keeping the glow element lit longer when fuel flows into the inverted head.
They can also help keep the engine running when the engine is running too rich for whatever reason.... but you are best advised to tune the engine properly in this situation.
11-22-2011, 10:55 AM
#4
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RE: nitro engines
I have a good article from a magazine that supports what OP just said. You can use different plugs and heat range to dial in when tuning. Back in the day we used idle bar plugs in engines that were wearing out and ready for a rebuild, four stroke plugs in older engines too.
Just to add to unders statement. All my glow engines are Nitro engines because I don't use FAI fuel.
I hear the term Nitro used for them all the time. Only time I have a term problem is when someone is asking about a glow engine and uses the term Gas.
Just to add to unders statement. All my glow engines are Nitro engines because I don't use FAI fuel.
I hear the term Nitro used for them all the time. Only time I have a term problem is when someone is asking about a glow engine and uses the term Gas.
11-22-2011, 12:23 PM
#6
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RE: nitro engines
The idle bar, was used to prevent fuel from extinguishing the glow coil as it splashed onto the cylinder head.
Modern fuel porting techniques have done away for the need of an idle bar plug... however they sometimes can be used to cure certain problems.
Modern fuel porting techniques have done away for the need of an idle bar plug... however they sometimes can be used to cure certain problems.
11-22-2011, 04:25 PM
#7
RE: nitro engines
Idle bar plugs began when engines started to be throttled and it was soon found out that idling was a problem, mainly because of the too simple carbs that couldn't regulate the idle mix very well. There weren't any mufflers back then either so exhaust baffles were used to help keep some heat inside the cylinder. The idle bar helped to stop any raw drops of fuel which collected in the crankcase at idle (because of the pathetic carbs ) from putting out the fire. Enya overcame the idle mix problem by introducing a carb that had twin needles where one needle tuned the idle mix and the other tuned the high speed but they had to revert to the earlier type carb because modellers thought the twin needle carb to be too complicated so didn't like it. It wasn't until about 10 years later that twin needle carbs began to appear again. Sometimes it doesn't pay to be ahead of the game .
The only engines where you have to be really careful about plug reach is on some of the older (non Schneurle) baffled piston engines. A lot of them had the plug off set to the transfer port side and the plug was located directly above the baffle. Too long a plug would then extend down into the baffle slot in the head and physical contact would be made. Not good. An idle bar plug would only make things even worse. With modern Schneurle port engines this can't happen unless you have a very small engine. My smallest is an OS .10 and I could only get slight contact by using a long reach idle bar plug without the washer fitted.
I must admit I'm surprised that the turbo plugs (as used by a lot of car engines) haven't started to appear on plane engines because they avoid problems with plug length, give a better combustion chamber shape and are now available in a quite a few heat ranges.
) from putting out the fire. Enya overcame the idle mix problem by introducing a carb that had twin needles where one needle tuned the idle mix and the other tuned the high speed but they had to revert to the earlier type carb because modellers thought the twin needle carb to be too complicated so didn't like it. It wasn't until about 10 years later that twin needle carbs began to appear again. Sometimes it doesn't pay to be ahead of the game .The only engines where you have to be really careful about plug reach is on some of the older (non Schneurle) baffled piston engines. A lot of them had the plug off set to the transfer port side and the plug was located directly above the baffle. Too long a plug would then extend down into the baffle slot in the head and physical contact would be made. Not good
. An idle bar plug would only make things even worse. With modern Schneurle port engines this can't happen unless you have a very small engine. My smallest is an OS .10 and I could only get slight contact by using a long reach idle bar plug without the washer fitted.I must admit I'm surprised that the turbo plugs (as used by a lot of car engines) haven't started to appear on plane engines because they avoid problems with plug length, give a better combustion chamber shape and are now available in a quite a few heat ranges.
11-22-2011, 04:52 PM
#8
My Feedback: (-1)
RE: nitro engines
I didn't have a clue it was Enya that developed the twin needle carb. I also haven't seen anyone pull out any idle bar plugs in a long time. I still have a pile of them from days of old. I do know guys that have started to try the plugs that they use in there cars. So far I haven't heard any talk about them in the bull pin.
I'm stuck in a rut, these days I pretty much only use the OS 8 and type F plugs in my engines. I think the smallest engine I have on hand are a few .25s but I haven't used them in years.
I'm stuck in a rut, these days I pretty much only use the OS 8 and type F plugs in my engines. I think the smallest engine I have on hand are a few .25s but I haven't used them in years.
11-23-2011, 05:05 AM
#9
RE: nitro engines
ORIGINAL: downunder
The only engines where you have to be really careful about plug reach is on some of the older (non Schneurle) baffled piston engines. A lot of them had the plug off set to the transfer port side and the plug was located directly above the baffle. Too long a plug would then extend down into the baffle slot in the head and physical contact would be made. Not good. An idle bar plug would only make things even worse. With modern Schneurle port engines this can't happen unless you have a very small engine. My smallest is an OS .10 and I could only get slight contact by using a long reach idle bar plug without the washer fitted.
The only engines where you have to be really careful about plug reach is on some of the older (non Schneurle) baffled piston engines. A lot of them had the plug off set to the transfer port side and the plug was located directly above the baffle. Too long a plug would then extend down into the baffle slot in the head and physical contact would be made. Not good
. An idle bar plug would only make things even worse. With modern Schneurle port engines this can't happen unless you have a very small engine. My smallest is an OS .10 and I could only get slight contact by using a long reach idle bar plug without the washer fitted.
I must admit I'm surprised that the turbo plugs (as used by a lot of car engines) haven't started to appear on plane engines because they avoid problems with plug length, give a better combustion chamber shape and are now available in a quite a few heat ranges.
ORIGINAL: Gray Beard
I'm stuck in a rut, these days I pretty much only use the OS 8 and type F plugs in my engines. I think the smallest engine I have on hand are a few .25s but I haven't used them in years.
I'm stuck in a rut, these days I pretty much only use the OS 8 and type F plugs in my engines. I think the smallest engine I have on hand are a few .25s but I haven't used them in years.
Nothing wrong with that. I use OS 8s in all of my engines.
Admittedly at this point it's just two, an OS 18 CV-RX and an OS 46AX, but still. I've never met an engine that didn't like OS 8s.
11-23-2011, 05:33 AM
#10
RE: nitro engines
ORIGINAL: downunder
Idle bar plugs began when engines started to be throttled and it was soon found out that idling was a problem, mainly because of the too simple carbs that couldn't regulate the idle mix very well. There weren't any mufflers back then either so exhaust baffles were used to help keep some heat inside the cylinder. The idle bar helped to stop any raw drops of fuel which collected in the crankcase at idle (because of the pathetic carbs) from putting out the fire. Enya overcame the idle mix problem by introducing a carb that had twin needles where one needle tuned the idle mix and the other tuned the high speed but they had to revert to the earlier type carb because modellers thought the twin needle carb to be too complicated so didn't like it. It wasn't until about 10 years later that twin needle carbs began to appear again. Sometimes it doesn't pay to be ahead of the game .
The only engines where you have to be really careful about plug reach is on some of the older (non Schneurle) baffled piston engines. A lot of them had the plug off set to the transfer port side and the plug was located directly above the baffle. Too long a plug would then extend down into the baffle slot in the head and physical contact would be made. Not good. An idle bar plug would only make things even worse. With modern Schneurle port engines this can't happen unless you have a very small engine. My smallest is an OS .10 and I could only get slight contact by using a long reach idle bar plug without the washer fitted.
I must admit I'm surprised that the turbo plugs (as used by a lot of car engines) haven't started to appear on plane engines because they avoid problems with plug length, give a better combustion chamber shape and are now available in a quite a few heat ranges.
Idle bar plugs began when engines started to be throttled and it was soon found out that idling was a problem, mainly because of the too simple carbs that couldn't regulate the idle mix very well. There weren't any mufflers back then either so exhaust baffles were used to help keep some heat inside the cylinder. The idle bar helped to stop any raw drops of fuel which collected in the crankcase at idle (because of the pathetic carbs
) from putting out the fire. Enya overcame the idle mix problem by introducing a carb that had twin needles where one needle tuned the idle mix and the other tuned the high speed but they had to revert to the earlier type carb because modellers thought the twin needle carb to be too complicated so didn't like it. It wasn't until about 10 years later that twin needle carbs began to appear again. Sometimes it doesn't pay to be ahead of the game .The only engines where you have to be really careful about plug reach is on some of the older (non Schneurle) baffled piston engines. A lot of them had the plug off set to the transfer port side and the plug was located directly above the baffle. Too long a plug would then extend down into the baffle slot in the head and physical contact would be made. Not good
. An idle bar plug would only make things even worse. With modern Schneurle port engines this can't happen unless you have a very small engine. My smallest is an OS .10 and I could only get slight contact by using a long reach idle bar plug without the washer fitted.I must admit I'm surprised that the turbo plugs (as used by a lot of car engines) haven't started to appear on plane engines because they avoid problems with plug length, give a better combustion chamber shape and are now available in a quite a few heat ranges.
I never had a problem idling the old engines. But I started in the mid 70's when the carbs were good and mufflers were faily common. In fact OS took off in part because they were about the first to include a muffler with every engine. Those engines would idle all day long without the idle bar plug, but would hesitate or quit when throttling up without the idle bar plug. In fact even with an idle bar plug you would have a problem if the idle bar was not perpendicular with the ports. The problem was the fuel flinging off of the piston baffle, especially when the velocity first picks up and throws off wet fuel collected on that baffle. At that time most Enya's were air bleed with midrange trim. ST, OS and others had twin needles, and Perry and HP had rotory idle mixture.
I am a bit dubious of Enya inventing the twin needle carb. Seems to me it was Kavan.
11-23-2011, 06:21 AM
#11
RE: nitro engines
ORIGINAL: Sport_Pilot
I am a bit dubious of Enya inventing the twin needle carb. Seems to me it was Kavan.
I am a bit dubious of Enya inventing the twin needle carb. Seems to me it was Kavan.
11-23-2011, 08:10 AM
#12
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RE: nitro engines
I use the Fox R/C Long glow plug with idle bar as my go-to glow plug for all of my 2-stroke engines (at least .25 cu in or larger, anyway). It's an excellent medium-hot plug that performs well in a wide variety of engine brands.
If the idle bar is no longer necessary, as other posters have suggested, it has also been my observation that idle bars certainly don't hurt anything, either. I've seen a great number of different 2-strokes respond wonderfully to the Fox R/C Long plug.
If the idle bar is no longer necessary, as other posters have suggested, it has also been my observation that idle bars certainly don't hurt anything, either. I've seen a great number of different 2-strokes respond wonderfully to the Fox R/C Long plug.
11-23-2011, 10:10 AM
#13
My Feedback: (-1)
RE: nitro engines
Idle bar plugs work just as well today as they ever did. Just not really needed. We only used them on really worn out engines that wouldn't idle and were blowing out dark gray snot and killing/shorting out plugs. They worked very well for our purpose. I just don't know anyone these days that run there engines to that point. I run 4 strokes for the most part. YS, and I have never met a four stroke that didn't like the OS type F. I have used a number of others but I like the Fs. I only run one two stroke these days and the OS 8s have always worked well. It's just another of those pilots choice deals.
11-23-2011, 12:13 PM
#14
RE: nitro engines
ORIGINAL: Gray Beard
I just don't know anyone these days that run there engines to that point.
I just don't know anyone these days that run there engines to that point.
I would. I don't have 60-80 bucks laying around for a piston and sleeve so I'm going to get every last revolution out of my engines I can. I do it with my 1:1s, too, my pickup's got 280K on the clock and I've got no plans of rebuilding it until it's so low on compression it won't move under it's own power anymore.
It's also why I'll spend the premium on OS, Saito and the like instead of buying Magnum, ASP and whatnot. Not saying those cheaper mills are inherently bad but I know the high-end stuff will last and last and last.
11-28-2011, 08:44 AM
#15
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RE: nitro engines
ORIGINAL: Gray Beard
Just to add to unders statement. All my glow engines are Nitro engines because I don't use FAI fuel. I hear the term Nitro used for them all the time. Only time I have a term problem is when someone is asking about a glow engine and uses the term Gas.
Just to add to unders statement. All my glow engines are Nitro engines because I don't use FAI fuel.
I hear the term Nitro used for them all the time. Only time I have a term problem is when someone is asking about a glow engine and uses the term Gas.
jess
