Best glow plug for engines

[Don Fry]

ED, don’t know, you may be right. I only buy plugs from trusted sources, but I might have bought one from a club mate. I thought modern plugs were plated, not solid platinum. One advantage, a copper core is less fragile. Downside the plating wears.

Last coppery one I chucked out had been in a DVII, probably 10 years of use.

[GrumpyGnome]

8 hours ago, Martin Harris - Moderator said:

 

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. 

 

You mean the 'cone' ones?

[Martin Harris - Moderator]

Yes

[Martin Harris - Moderator]

Off topic posts deleted.  Fuel debate, although related to plug life, is best discussed elsewhere. 

[J D 8]

I have used several makes of plug with Tailor, Fireball as well as OS and Enya. All have given good service. Also had good service from Model Technics plugs, an interesting one they do is a two stroke plug for inverted engines. Looks a bit like a four stroke plug, not sure it makes much difference.

   The main thing for plug life is not to over power them. As mentioned before the general use of starter sticks and on board glows has reduced the chances of the plug being driven to brilliant sun orange by the user turning up the power on starter panel trying to get the motor going.

   

[GrumpyGnome]

I know not all will agree, but an onboard glow has transformed my inverted 90FS.  It's ultra reliable and you can almost count the idling revs by eye!

 

It uses a separate LiPo for power and is controlled by my transmitter....

 

Switch up = glow off (no power)

Switch central = low glow power - maintenance mode

Switch down = high glow - starting mode

After 30 seconds on high glow, it automatically switches to low glow

Above 25% throttle, glow switches off

Engine kill reduces throttle and turns glow off.

Edited February 8, 2023 by GrumpyGnome

[Nigel R]

8 hours ago, J D 8 said:

had good service from Model Technics plugs, an interesting one they do is a two stroke plug for inverted engines.

As have I, but they're no longer trading. 

[Paul De Tourtoulon]

7 hours ago, GrumpyGnome said:

I know not all will agree, but an onboard glow has transformed my inverted 90FS.  It's ultra reliable and you can almost count the idling revs by eye!

 

It uses a separate LiPo for power and is controlled by my transmitter....

 

Switch up = glow off (no power)

Switch central = low glow power - maintenance mode

Switch down = high glow - starting mode

After 30 seconds on high glow, it automatically switches to low glow

Above 25% throttle, glow switches off

Engine kill reduces throttle and turns glow off.

I use one when I try a new plane out, with a  new or just bought second hand 4 stroke  rigged up on a switch that  turns it on to start and off at 1/3 throttle it's good insurance till you have got it running properly.

[Paul De Tourtoulon]

I used to use a Graupner 2v 10 amp lead battery with a 1 metre wire, that was indestructible it would not kill any plug, but my glow driver is a real plug killer.

[Jon H]

8 hours ago, GrumpyGnome said:

I know not all will agree, but an onboard glow has transformed my inverted 90FS. 

 

OBG should not be required assuming the engine is tuned correctly and the tank is in the right place. Tank placement is as important with OS or any other brand as it is with Laser and its why i make such a song and dance out of it. Its slow run tuning that usually is the issue and so many of the problems connected with glow engine reliability come down to tank placement and slow run tune. Clearly, tuning is impossible to get right if the tank is in the wrong place so often the whole thing has gone wrong before the model is even finished. 

 

High nitro/high oil fuel can also drown a plug, especially if the tuning is out. My own OS91 was inverted for yonks in an ARC Carosel and was always well behaved. I was 17 back then and know a bit more now, but i have rebuilt the engine after years of abuse and last i ran it the idle was well below 2000. In fact most 4 strokes should idle between 1800 and 2500. 2500rpm for a small one like a 30 or 40, and progressively slower as you get bigger. 2000 should be easy to achieve with no glow on a 91. If not, something is wrong. 

 

In any case, i am not a fan of OBG as they mask problems which are usually best corrected another way. They also tend to introduce reliability issues of their own and can damage plugs as they are powered up for longer than they need to be (admittedly unlikely with your use case) and some OBG units really slap plugs with power making them glow almost white hot. The old temperature sensing ones were not so bad (were they SM services?) but even so, i would save the cost, weight, space, and potential loss of plug life and make sure my installation was 100% from the get go. 

 

The OS91 is a great engine and they run well. Irrespective of any personal preferences glow support should not be needed with that one. 

 

 

[J D 8]

              The type of onboard glow I use is run from a small two cell lipo and gives the right voltage to the plug. Press the button and you have around fifteen/twenty seconds of glow to get the motor going, after that it switches off and does not come on again unless you press the button

      With the Testors and Cox engines one had to be careful, in times gone by we used to cut the end cell off a 12v or 6v lead acid batt which gave you two volts and had to be controled by wire length as with Paul above.

Edited February 8, 2023 by J D 8
spelling

[Paul De Tourtoulon]

My onboard glows are driven by a single sub-c of 2500/3500 mah ni-hm battery.

[Jon H]

54 minutes ago, Paul De Tourtoulon said:

My onboard glows are driven by a single sub-c of 2500/3500 mah ni-hm battery.

 

That should be fine, its the lipo ones that i have seen cause trouble. A friend had one on a nitro car and he was burning through plugs at quite a rate. 

[Peter Christy]

One other point that is often over-looked - especially amongst those who run older engines - is that many were designed to use long reach plugs, which seem to be almost unavailable these days.

 

For example, Webra cross-flows (Blackhead and earlier) and most Super-Tigres. They will run on as OS8, but its less than optimal!

 

Quick tip: Most 4-stroke plugs seem to be long-reach, and seem to work fine in the above mentioned engines. They are also "hotter" plugs, which seems to suit the low or no nitro fuels such engines require.

 

However, do check to make sure the plug doesn't hit the piston at TBC before firing it up! Slowly crank by hand, or better still, take the head off and make sure the plug sits flush in the head.

 

--

Pete

[Jon H]

Very true Pete. The model technics 3d plug was long reach. Not sure if you can find them these days though. The moki 180 and 210 ran well on F plugs if i remember rightly, but i consider them and the engines you mention an exception as they are not especially common these days. 

 

If you arent sure about plug length use a short plug like the OS 8 or you may end up punching a hole through your piston! I know you mentioned it but its worth saying twice! 

Edited February 8, 2023 by Jon - Laser Engines

[GrumpyGnome]

2 hours ago, Jon - Laser Engines said:

 

OBG should not be required assuming the engine is tuned correctly and the tank is in the right place. Tank placement is as important with OS or any other brand as it is with Laser and its why i make such a song and dance out of it. Its slow run tuning that usually is the issue and so many of the problems connected with glow engine reliability come down to tank placement and slow run tune. Clearly, tuning is impossible to get right if the tank is in the wrong place so often the whole thing has gone wrong before the model is even finished. 

 

High nitro/high oil fuel can also drown a plug, especially if the tuning is out. My own OS91 was inverted for yonks in an ARC Carosel and was always well behaved. I was 17 back then and know a bit more now, but i have rebuilt the engine after years of abuse and last i ran it the idle was well below 2000. In fact most 4 strokes should idle between 1800 and 2500. 2500rpm for a small one like a 30 or 40, and progressively slower as you get bigger. 2000 should be easy to achieve with no glow on a 91. If not, something is wrong. 

 

In any case, i am not a fan of OBG as they mask problems which are usually best corrected another way. They also tend to introduce reliability issues of their own and can damage plugs as they are powered up for longer than they need to be (admittedly unlikely with your use case) and some OBG units really slap plugs with power making them glow almost white hot. The old temperature sensing ones were not so bad (were they SM services?) but even so, i would save the cost, weight, space, and potential loss of plug life and make sure my installation was 100% from the get go. 

 

The OS91 is a great engine and they run well. Irrespective of any personal preferences glow support should not be needed with that one. 

 

 

My tank is a little higher than optimal, but I didn't really want to hack around with a new airframe for under 1/4"...

 

Engine is an SC90.

 

Glow plug on the OBG glows the same colour (by eye) as when attached to a glow stick, using a current of 1.4V when it's on high; on low, it's MUCH less bright, with a voltage of 0.8V

 

It uses a separate 2S Lipo to the unit.  

[Jon H]

9 minutes ago, GrumpyGnome said:

My tank is a little higher than optimal, but I didn't really want to hack around with a new airframe for under 1/4"...

 

Engine is an SC90.

 

Glow plug on the OBG glows the same colour (by eye) as when attached to a glow stick, using a current of 1.4V when it's on high; on low, it's MUCH less bright, with a voltage of 0.8V

 

It uses a separate 2S Lipo to the unit.  

 

 

If the top of the tank is 1/4 above the carb that should be ok. SC and asp engines shipped with mega rich slow run needles (over 3 turns!) and their carbs were not always brilliant. I made a new barrel screw for the Sanye (parent companty of SC/ASP etc) carb fitted to my RCV and the performance was much improved.