Author Topic: The right glow plug (Read 3459 times)

Gordon Tarbell · « **on:** August 12, 2017, 11:20:26 AM »

The right glow plug makes all the difference in the world. Went to the Chumley trimming clinic with borrowed SV-11 powered by Stalker 61 RE LT pro with 13-6 prop (Zoar maybe). Put up a flight , I flew my usual terrible pattern but had same great engine run that I have been getting in previous weeks. Second flight had a little hicup and ran kinda funny at end and shut off prematurely . Pulled plug and there was a big Ol' tater on that thing. Did not have a merlin 2004 which came out so put some Idle bar plug in that was new in package. Figured no big deal. Wrong, Wrong , Wrong. That thing kicked and spit, and jumped up and down. Brian launched the plane anyway hoping it would calm down. That thing finally cleaned out and ran like its tail was on fire. Not Good! That was my last flight for the day. Since I do mix my own fuel and am not hesitant to question my work first, I went home and double checked my fuel components that I use to mix up with Hydrometer also checked visually for other type contaminants.All check spot on for purity and cleanliness . Couple of days later I call up to order Merlin plugs and tell the owner(forgot his name) about what happened . He asked me if I indexed the Idle bar plug, I said no. He informed me on many engines the Idle bar must be indexed to get benefit. Then suggested I not run that style at all in that engine. Next flying session with new Merlin 2004 hot plug the engine was back to running like a metronome, nice even beat. Glow pugs can make big difference in run quality. Lesson Relearned.

Dennis Toth · « **Reply #1 on:** August 12, 2017, 01:30:46 PM »

Gordon,
When you say "index" the idle bar I assume this means to adjust the final tight position so that it aligns relative to some part of the engine (exhaust port or intake ports?), correct? What part and how did he indicate you could make this adjustment - different thickness plug gaskets? Please explain.

Best, DennisT

Brett Buck · « **Reply #2 on:** August 12, 2017, 02:16:06 PM »

Quote from: Dennis Toth on August 12, 2017, 01:30:46 PM

Gordon,
When you say "index" the idle bar I assume this means to adjust the final tight position so that it aligns relative to some part of the engine (exhaust port or intake ports?), correct? What part and how did he indicate you could make this adjustment - different thickness plug gaskets? Please explain.

Various shims under the glow plug washer to align the bar with the engine somehow. People have told me about doing this for years, and how it made a huge difference. In engines that ran nominally with a particular plug, it didn't seem to matter or even be detectable. For engines that wouldn't run right with a particular plug, changing it seemed to make a difference in how badly it ran, possibly, in some cases.

It was also unclear if the effect was the orientation of the bar WRT the engine or just changing the compression. Many times, turning it just enough to line it up with the baffle (or perpendicular, depending on who you talked to) would have some positive effect. Then, shimming it further, say, 180 degrees from the initial position so the bar wound up in the same random orientation you started with, it worked still better. I figured it was either the plug depth and or the change in the compression due to the varying plug depth, that made the difference, not where the bar ended up.

It was a moderately common tweak back in the Good Old Days(tm) of stunt to adjust the degree and position of the 4-2 break by sticking an extra glow plug washer under the plug, to slightly adjust the compression. Stuff like that is why the Good Old Days(tm) sucked, for the most part.

There's probably something to it, and probably something to where the weld ends up on conventional plug, but the effect appears to be pretty small and if it's that touchy to get it to run properly, it's too touchy to trust day-to-day in a stunt plane. Basically you had better be able to grab a plug out of the package and screw it in without experimenting with the idle bar direction and varying shims to get it lined up a particular way. As far as I can tell, the relationship between where the bar or weld winds up is random with respect to the threads, so its unique to each plug and engine.

Now, I have engines with head buttons so I could orient it in any direction without changing either the plug depth or the compression ratio, but haven't bothered to experiment with that. AND, I use Thunderbolt 4-cycle plugs with no idle bar, so it would be about lining the element weld with the engine somehow. I have managed to find other things to do with my limited field time.

Brett

Gerald Arana · « **Reply #3 on:** August 12, 2017, 03:53:57 PM »

Quote from: Brett Buck on August 12, 2017, 02:16:06 PM

Various shims under the glow plug washer to align the bar with the engine somehow. People have told me about doing this for years, and how it made a huge difference. In engines that ran nominally with a particular plug, it didn't seem to matter or even be detectable. For engines that wouldn't run right with a particular plug, changing it seemed to make a difference in how badly it ran, possibly, in some cases.

It was also unclear if the effect was the orientation of the bar WRT the engine or just changing the compression. Many times, turning it just enough to line it up with the baffle (or perpendicular, depending on who you talked to) would have some positive effect. Then, shimming it further, say, 180 degrees from the initial position so the bar wound up in the same random orientation you started with, it worked still better. I figured it was either the plug depth and or the change in the compression due to the varying plug depth, that made the difference, not where the bar ended up.

It was a moderately common tweak back in the Good Old Days(tm) of stunt to adjust the degree and position of the 4-2 break by sticking an extra glow plug washer under the plug, to slightly adjust the compression. Stuff like that is why the Good Old Days(tm) sucked, for the most part.

There's probably something to it, and probably something to where the weld ends up on conventional plug, but the effect appears to be pretty small and if it's that touchy to get it to run properly, it's too touchy to trust day-to-day in a stunt plane. Basically you had better be able to grab a plug out of the package and screw it in without experimenting with the idle bar direction and varying shims to get it lined up a particular way. As far as I can tell, the relationship between where the bar or weld winds up is random with respect to the threads, so its unique to each plug and engine.

Now, I have engines with head buttons so I could orient it in any direction without changing either the plug depth or the compression ratio, but haven't bothered to experiment with that. AND, I use Thunderbolt 4-cycle plugs with no idle bar, so it would be about lining the element weld with the engine somehow. I have managed to find other things to do with my limited field time.

Brett

Brett,

I think this falls in line with Larry's "Monocoat" jobs.......Golf, snark, giggle!

Jerry

Brett Buck · « **Reply #4 on:** August 12, 2017, 04:49:23 PM »

Quote from: Gerald Arana on August 12, 2017, 03:53:57 PM

Brett,

I think this falls in line with Larry's "Monocoat" jobs.......Golf, snark, giggle!

Jerry

No, this is hardly the first time I have heard this theory, various people have definitely looked at this before, and it at least makes some conceptual sense.

Brett

Peter Nevai · « **Reply #5 on:** August 12, 2017, 05:36:52 PM »

Since we are on the topic of glow plugs, and the average cost of one of these is around 6 to 9 bucks a pop. How does on figure out which brand will work best in their engine? This used to be easier and a whole lot cheaper. Today a dozen plugs can set you back nearly $100. So without tossing a ton of money away experimenting with glow plugs. There used to be reliable standby plugs that almost allways worked on any motor. "GloBee" K&B, Fox. but these are gone now and manufacturers seem to rate them by what RC Car engine you stick them in. Almost non tell you if it is a short or long reach plug. As far as Idle bar plugs are concerned, I have not seen one of them for sale in ages.

Gordon Tarbell · « **Reply #6 on:** August 12, 2017, 06:15:47 PM »

For the record, the Idle bar orientation thing is not my theory, nor did I observe it in my engine. I was made aware of this theory by the glow plug manufacturer as a possible reason for faulty run. I do know that the Idle bar plug I used, for what ever reason, did not produce the engine run I was seeking. The Merlin 2004 hot plug did, of which I now have multiples in my flight box . As has been stated there are far more important things to take up my time than experimenting with glow plugs. I will stick to my original words "The right glow plug makes a difference".

RandySmith · « **Reply #7 on:** August 12, 2017, 06:27:57 PM »

Quote from: Peter Nevai on August 12, 2017, 05:36:52 PM

Since we are on the topic of glow plugs, and the average cost of one of these is around 6 to 9 bucks a pop. How does on figure out which brand will work best in their engine? This used to be easier and a whole lot cheaper. Today a dozen plugs can set you back nearly $100. So without tossing a ton of money away experimenting with glow plugs. There used to be reliable standby plugs that almost allways worked on any motor. "GloBee" K&B, Fox. but these are gone now and manufacturers seem to rate them by what RC Car engine you stick them in. Almost non tell you if it is a short or long reach plug. As far as Idle bar plugs are concerned, I have not seen one of them for sale in ages.

I stock 100s of the Merlin Plugs 2004 and 2005 work great for most stunt engines, both of these are a hot plug and are also a " Big Bore
plug, so they run hotter and that keeps the engine running smooth and clean in maneuvers, I also stock the SIG Rc ilde bar, but the Merlins work every bit as well as the defunct Thunder Bolts did, and the are cheaper, but very well made

Randy

Brett Buck · « **Reply #8 on:** August 12, 2017, 10:05:00 PM »

Quote from: RandySmith on August 12, 2017, 06:27:57 PM

I stock 100s of the Merlin Plugs 2004 and 2005 work great for most stunt engines, both of these are a hot plug and are also a " Big Bore
plug, so they run hotter and that keeps the engine running smooth and clean in maneuvers, I also stock the SIG Rc ilde bar, but the Merlins work every bit as well as the defunct Thunder Bolts did, and the are cheaper, but very well made

Any comment on the "idle bar orientation" thing? I never found it to make any consequential difference unless there was something else already wrong, in which case, rotating it around had at best ambiguous results.

Brett

Lauri Malila · « **Reply #9 on:** August 13, 2017, 02:11:59 PM »

I'm afraid that to find out the truth would require much more systematical testing than just comparing a well-proven barless plug with "some idle-bar plug". The symptons you describe just indicate a bad heat range to me.
And a systematical test means that you should not change the chamber geometry & volume, so shimming the plug up or down is not a good idea. So a head button would be the only good solution.
In my opinion the bar orientation has a homeopathic effect or no effect whatsoever. I haven't really experimented with them but my opinion is based on my work with interaction of highly efficient (stunt)scavenging and asymmetric cylinder heads. Sometimes I, from curiosity or by accident, I tilt the head from the good position (in 1/8 turn steps), and the end result is allways worse. And trend is allways to same direction, it in not possible to for example alter the direction of running symmetry or some systematical hysteresis issues by making these things purposely asymmetric. L

Fredvon4 · « **Reply #10 on:** August 13, 2017, 05:22:38 PM »

I used to clock...index ....spark plugs for V8 racing engines and could easily see on a Dyno the relative gains or losses

For single cylinder stunt glow, at the competition levels of some of the top champs, I suspect there may be some optimum plug orientation ----but it is probably inconsequential.
I think what Brett is telling us is the quality, repeat-ability, and durability, are much more important

If I was in the Racing--- or any other speed type MAX power event format -----I would certainly experiment with "indexing" as well as brand, heat range, format (IE, turbo, nelson) ...I know there are meager gains to be realized

I used to be neighbors with a RC Boat racer... 0.60s if I remember... 65%N, additives, (retrospect probably bad stuff these days) and HE clocked his plugs ----as well as significantly decreased his compression... fun fact.... he used to beg me for the Duke Fox magic dust to break in engines....his belief was, a nearly worn out ---very very loose engine--- could be set to insane RPMs and still win races...and his did

RandySmith · « **Reply #11 on:** August 13, 2017, 07:46:40 PM »

Quote from: Brett Buck on August 12, 2017, 10:05:00 PM

Any comment on the "idle bar orientation" thing? I never found it to make any consequential difference unless there was something else already wrong, in which case, rotating it around had at best ambiguous results.

Brett

Hi Brett
I have tried that many times, to my mind if you have a plug that is so critical that it has to be a a certain place in the rotation, then its one you do not need to use, I have never had any idle bar that I had to turn to different locations, and I tried this a lot with the single and double plug heads I made. I thought I would see a difference in those head buttons, but never did.
AN idle bar would need to be pretty COLD to not run well in any position,
If you think about it the non bar plugs would , or should be susceptible to stumbling .
The best plugs I am seeing for our stunt use , are NON idle bar , BIg BORE . and the Best RC idle bar plugs I have ever used were the OLD Glo BEE with the super wide bar on them, about 3 times wider than one you would typically see .
Bottom line, it much more important to pick the right heat range, for us that is a HOT plug

Randy

Brett Buck · « **Reply #12 on:** August 13, 2017, 07:58:22 PM »

Quote from: RandySmith on August 13, 2017, 07:46:40 PM

Hi Brett
I have tried that many times, to my mind if you have a plug that is so critical that it has to be a a certain place in the rotation, then its one you do not need to use,

That's what I concluded, if its that touchy, use something else or solve it otherwise. I screwed around with the "clocking angle" in different variations on my one problem engine and it made *no* difference in that case, either by shimming the plug or rotating the head to each of the 6 possible positions, ran exactly the same (that is to say, would still quit at random like you flipped a switch).

I haven't used idle bar plugs in many years now, having convinced myself that the function supposedly served by the idle bar ("protecting the element from raw fuel") either didn't matter or didn't work the way it was purported to work if everything else was OK. Having an idle bar doesn't seem to hurt anything, either, so we ran the Thunderbolt 4-cycle for years because it was originally really cheap and it gave marginally more power/allowed marginally richer settings than anything else, the next best choice being the Thunderbolt RC. That was a long time ago, I bought two cards of them at $1.59, and I am coming to the last of that batch now, with a dozen Thunderbolt "Big Bore" that may have been the last thing tossed out the door at Hobby People before they locked it.

Brett

RandySmith · « **Reply #13 on:** August 15, 2017, 12:12:16 PM »

I have many homemade engines , or ones with homemade button heads, and I have played with them a lot, it never made any difference clocking them, maybe it was just because I had very good plugs in them, The big difference is not clocking, but moving the plug up and down in the threaded hole, moving them up seems to make the plugs act colder, moving deeper in the chamber makes them act hotter,
The Eyna 3 for me in not any better of a plug , than the ones I run, I think this is because it is a short plug, if I sink the Enya 3 or 4 deeper into the chamber, its much better, runs cleaner , and doesn't seem to affect the life

Randy

Peter Nevai · « **Reply #14 on:** August 16, 2017, 05:15:15 PM »

It used to be that you could get two types of plugs. Long Reach and Shorts. Engines 35 or bigger needed long reach plugs. I have in the attached photo a couple old plugs, a long and short. Do they no longer come in shorts and longs, if not how do they come now? I know for certain that my FSR40, VF46, And H60 would not take short plugs as they would be buried in the cylinder head. The plug on the left is from a fox 25 and could not take a longer plug

Steve Helmick · « **Reply #15 on:** August 17, 2017, 03:58:50 PM »

Glowplugs still come in short and long reach...but OS appears to only have one length, which is a "medium". Blame it on the metric system. As a general rule, .15 engines and smaller use a short glowplug. I expect that the reason the glowplug on the left doesn't clear the piston on your Fox .25 is simply because of the idlebar. A long glowplug should fit fine without an idle bar.

Like Brett, I have a fair stock of Thunderbolt glowplugs, and that's despite giving away at least a half dozen to folks that were suffering with Fox glowplugs. Every time, the subject engine did an about-face and ran nicely with a Thunderbolt. By the way, K&B and McCoy glowplugs are still available. Ohlsson Corporation makes K&B glowplugs for RJL/Mecoa, which owns K&B, Fox, Johnson, McCoy, Forster, etc., etc. Dunno much about McCoy glowplugs, not having used any since the early '60's. It would not surprise me to find out they're also made by O.C., but I don't know that for fact. I'd like to find out. Also SIG glowplugs. I've only heard good reports on both. When I was a kid, we usually ran OK Cub or Johnson glowplugs, but occasionally O&R's. We knew then that the O&R glowplugs ran better, but were expensive. I remember 49 cent glowplugs.

For myself, I'm a happy camper with O.C. plugs, and strongly dislike Fox and Fireball glowplugs. OS and Enya glowplugs are known to be good stuff, but spendy. Tower sells their own brand, source unknown. Anybody tried them? Considering the bad things that can happen to a difficult to replace stunt engine, I'm really not too interested in trying unknown stuff if I don't need to.

Steve

Brian Hampton · « **Reply #16 on:** August 17, 2017, 08:45:49 PM »

Quote from: Steve Helmick on August 17, 2017, 03:58:50 PM

...OS appears to only have one length, which is a "medium". Blame it on the metric system.

Both OS and Enya plugs have always been a "medium" length but for some reason OS cylinder heads are machined so that neither long or medium plugs fit correctly although long is a better fit. Medium length plugs are an exact fit in my Enya 61's though. I'm not quite sure how the metric system is to blame though

.

Author Topic: The right glow plug (Read 3459 times)

Gordon Tarbell

The right glow plug

Dennis Toth

Re: The right glow plug

Brett Buck

Re: The right glow plug

Gerald Arana

Re: The right glow plug

Brett Buck

Re: The right glow plug

Peter Nevai

Re: The right glow plug

Gordon Tarbell

Re: The right glow plug

RandySmith

Re: The right glow plug

Brett Buck

Re: The right glow plug

Lauri Malila

Re: The right glow plug

Fredvon4

Re: The right glow plug

RandySmith

Re: The right glow plug

Brett Buck

Re: The right glow plug

RandySmith

Re: The right glow plug

Peter Nevai

Re: The right glow plug

Steve Helmick

Re: The right glow plug

Brian Hampton

Re: The right glow plug