Best glow plug for engines

[EGB 953]

Hi,

 

Is there a table somewhere or a guide to the ideal glow plug for different engine sizes and combinations? I am running an OS8 on a OS46AF, and was wondering if I would get better performance from a hotter or cooler plug? Does the prop size make a difference to the glow plug to choose? Any advice welcome. 

[Denis Watkins]

https://www.os-engines.co.jp/english/line_up/glowplug/index.html

 

There is a lot of confusion over the use of Hot or Cold plugs

And has more to do with the size of the lump of aluminium that you fly.

A large motor can retain heat more readily than a small motor.

Your plug choice is fine for your motor.

A larger lump of metal like a 90 can use a cooler plug.

A small 46 lump would better on a medium/ hot

21 motors use a hot plug.

One plug does not suit all

Edited February 6, 2023 by Denis Watkins

[Jon H]

As far as i am concerned there are only 2 plugs in the whole world. The OS 8 for all 2 strokes, and the OS F for all 4 strokes. 

 

In theory messing with plugs can offer a performance uplift, but only if you have your engine tuned absolutely perfectly and on a fuel that will take advantage of it. Things like competitive racing, nitro buggies at a competitive level, sure there is performance there so go for it. But for 99% of modellers using a bog stock engine and flying at the weekend its not worth worrying about it. 

 

You are more likely to see a performance uplift by changing propeller than you are anything else. The correct prop can transform the performance of a model. 

[Nigel R]

Enya #3 is also good, and about equivalent to the OS #8.

 

I have a bunch of OS #8, Enya #3, I can't tell the difference.

 

Edited February 6, 2023 by Nigel R

[Solly]

Weston UK have a good range of plugs, 2 stroke and 4 stroke. I’ve used them for years and find them excellent.

[John Lee]

6 hours ago, Jon - Laser Engines said:

As far as i am concerned there are only 2 plugs in the whole world. The OS 8 for all 2 strokes, and the OS F for all 4 strokes. 

 

Agreed.

 

When I disposed of the last of my glow engines & went all electric a decade ago I was left with more than a full card of each in stock. I eventually got around to selling them when there was a bit of a shortage a few years later and they turned out to be a nice little earner!

[EGB 953]

Thanks all for the sound and very consistent advice!

 

[Paul De Tourtoulon]

Any 2 strokes above 5cc an Enya 3 and especially helicopter engines, 4 strokes OS 'F'.

 

 Ps, Rossi N° 4 for planes and N° 5 for helicopters, but they seem rubbish today.

Edited February 6, 2023 by Paul De Tourtoulon

[John Stainforth]

3 hours ago, John Lee said:

 

Agreed.

 

When I disposed of the last of my glow engines & went all electric a decade ago I was left with more than a full card of each in stock. I eventually got around to selling them when there was a bit of a shortage a few years later and they turned out to be a nice little earner!

You may regret that, when you get tired of the electric and go back to i.c.!

[GrumpyGnome]

5 hours ago, Solly said:

Weston UK have a good range of plugs, 2 stroke and 4 stroke. I’ve used them for years and find them excellent.

 

Are they OK for SC, and Thunder Tiger four stroke engines?  The Weston web site says....

 

[Frank Skilbeck]

2 hours ago, GrumpyGnome said:

 

Are they OK for SC, and Thunder Tiger four stroke engines?  The Weston web site says....

 

Note they do both types of plug, for SC and Thunder Tiger you'd want the PP type from Weston. Must admit I've never seen an engine that uses the cone type seal. 

[Martin Harris - Moderator]

More common on high performance car glow engines, I believe.

[GrumpyGnome]

Cheers, I'll remember that.  They're significantly cheaper than the OS F plugs I just treated some of my engines to!

[David Ovenden]

For me it's always OS F for four strokes. Nothing else I've tried is as good as the OS plug.

Enya no 3 and OS no 8 are both good plugs for 2 strokes .

[Nick Somerville]

So how often do people change their plugs? I have been back modelling for four years now and have been running four Laser engines (one a twin) and an OS 120 fs. All have OS F plugs and I have a few spares, but haven’t had cause to use them. Do they get stuffed due to  improper power to them or do they just eventually wear out. If so what is the typical life expectancy? 

[Jon H]

I dont usually change a plug unless the engine starts to misbehave. 

 

All of the models listed below are on their original OS F plugs from when the model was new. First flight dates are shown and all models have flown regularly for the most part. No 4 or 5 year storage screwing the result.  

 

Sea Fury - Dec 2014

Nieuport - August 2013

Hurricane - Sep 2016

 

The Engine in my P39 is on its original plugs and its flown about 6 years in there and maybe another 5 before it in another model? Cant remember. These plugs are starting to show signs of being a bit fed up so i might change them. 

 

All the rest of my models are newer or have plugs of unknown age as i have lost track of where they came from. 

 

Plugs last longer if the engine is correctly tuned (ie, tuned for peak performance not running rich), the engine is not roasted to death in a rubbish cowl, and the throttle is not simply pinned at the top and left there all day. 

 

Oh and fuel makes a difference. Castor kills plugs as they carbon up over time. No castor!

Edited February 7, 2023 by Jon - Laser Engines

[Martin Harris - Moderator]

10 hours ago, Martin Harris - Moderator said:

More common on high performance car glow engines, I believe.

 

1 hour ago, GrumpyGnome said:

Cheers, I'll remember that.  They're significantly cheaper than the OS F plugs I just treated some of my engines to!

Note that they are not suitable as conventional plug replacements - the head seating area is machined for them and they use a different thread size. 

[Don Fry]

Modern plugs do wear out, the platinum plating wears off, and it looks coppery. Or the go matt, too much heat, improper power, esp running at speed with power on.

I lose plugs when I have a problem, change plug is the quick, lazy solution, then I find out what the problem realy was, and don’t store the used plug properly. 
But not abused, they last a very long time. 
 

[J D 8 - Moderator]

       Having operated glow motors for forty plus years [ only diesel before ] I have to say I only change plugs if an engine starts to play up, it is the simple easy thing to do before moving on to checking fuel system ect.

 Have only had a couple of complete fails [ no glow at all ] Those that have gone duff but still sort of work get the heave ho so as not to get mixed with good ones.

[Paul De Tourtoulon]

I shall try an OS 8 in my little OS 30Fs as It cuts out at half throttle on the OS F, ( instructions castor oil only ) maybe my power panel has something to do with it,,,

 

Come on Jon still Castor bashing, My OS 80fs has been run on all sorts of fuel and Never without Caster since I bought

it second hand at the 1990 Avignon model show still on it's original OS 'f', My Laser also runs well with Caster, I have no idea what plug is in it as it just keeps running, I can give you a list of my old planes dating back a while still running well on Castor and Rossi 5 plugs.

[Jon H]

Castor is a dead lubricant. Just accept the fact and move on. 

 

I run a number of OS engines (15fp, FS26, FS40, FS40s, FS52s, FS91sII, FF240, FF320, FT300), some of which stipulate 20% castor in their original 1980's instructions. They all run 15% synthetic. The new 15% oil laser fuel from Optifuel is really good and my FS40 and enya 53 have never performed better. 

 

On your FS30, the correct plug is the F so i would stick with that. Flame out at half throttle is likely a lean cut so i would have a look at the air bleed screw. 

[Martin Harris - Moderator]

Plenty of other discussions on castor in fuels - let’s not get sidetracked please. 

[Jonathan W]

Ref the OS 30FS, I suggest to try running it with and without exhaust pressure feed to the fuel tank, see which suits best. This did solve my issues with a 26FS.

[Paul De Tourtoulon]

19 minutes ago, Jonathan W said:

Ref the OS 30FS, I suggest to try running it with and without exhaust pressure feed to the fuel tank, see which suits best. This did solve my issues with a 26FS.

Thanks, I remember my first 4 stroke that I bought new in 1984 an OS .61 and that only ran without pressure, but at that time no one understood how they worked.

[Engine Doctor]

I can only remember a couple of plugs failing over the years . The main cause was if using a flight box power panel and either pluging in your glow clip in the wrong socket or having the glow feed turned up too high. The advent of glow sticks and decent capacity NiMh solved  that problem/issue  . 

6 hours ago, Don Fry said:

Modern plugs do wear out, the platinum plating wears off, and it looks coppery. Or the go matt, too much heat, improper power, esp running at speed with power on.

 

Don if a plug element  turns a coppery colour then its probably one of the fake one circulating . I haven't bought any plugs for years as i have collected quite a few . There are a few  reports of the fake OS plugs circulating . Identifiable by a poor print quality on the packaging ( look on ebay loads on offer ! ) OS have hi-lighted the problem and I believe there are posts on here about it. These fake plugs  turn a  coppery colour after a few flights and stop  igniting fuel properly.

Plugs were often sold at shows some years at very competitive/bargain prices . After a couple of flights you would notice your engine had no compression then realise that the seal had melted in the "bargain" Plugs.😗 

Genuine OS or Enya are very good as are YS plugs  but I think they are re-packaged OS plugs .  

Edited February 7, 2023 by Engine Doctor