shonny

Your last point is very relevant, but then there is the question of timing. With an electronic ignition system that is taken care of, but, like with ordinary glow engines, it will be a question of when ignition takes place. Too late - reduced power, too soon - knocking. And then there's the temperature . . .

earlwb

Yes that is true. The glow plug is basically fixed ignition timing. But you can control it by making changes to the compression ratio (within limits of course). Also engine heat is important for controlling ignition timing too. The timing automatically advances as the engine heats up. So when cold the timing is retarded and as the engine heats up the timing advances. The timing advance curve usually is quite good too. Even better than the simple two step timing advance that is in many of the CDI ignition units everyone uses. You can see the effect with a glow engine too, as usually they tend to be fairly easy to start when cold. But when hot, it is harder to start them. They tend to kick back quite a bit harder when hot.

prigai

That is true for almost anything, my wife is a great example

spaceworm

I hope you don't have the artist's (formally known as Hobbsy), experience losing valuable parts.

shonny

Hm, you have that ol' limerick in mind:

There once was a girl named Jill
Who used dynamite sticks for thrill
They found her v....
In North Carolina
And bits of her t..... in Brazil

?????

captinjohn

Cool her down with your fire hose !

prigai

This method works better in a colder climate maate,
Sheilas Downunder get Smoking Hot when fire hosed!

Going back to the thread, I've completed the conversion of the Supertigre G3250 engines I got a couple of weeks ago.
I will try one with a G5 plug at the first opportunity, it should work well for any 2 stroke.
Watching the Diesel RC video I'm not sure it will be as good for 4 stroke engines, if one requires onboard battery for reliable idle any old glow plug will do!

shonny

Am waiting for a button die with 1/4"-32 thread from Tower to make a dummy plug same size as the G5 to make sure that the piston doesn't hit the plug. To check the distance from the plug to the pistin I will make a small screw inside the dummy so I can measure the distance to the plug. Also, according to my mate Kenny, it is important to check the compression in the motor as that is much more critical with petrol (gas). And also remember to isolate the carby from the motor to avoid vaporising.

prigai

Just use a discarded glow plug, clean the old filament out and thread with 3mm fit. The G5 is a bit longer than OS 'F' but will fit most engines. You can always use additional glow plug washers. Vaporising can be a real issue, fortunately I always used thermal isolators so never been one of my issues, but many of the original glow conversions ran into trouble as the carb adapter is made of aluminium and will conduct heat if not isolated. One advantage of glow conversions is the front carb configuration that gets all the cooling, on the flip side, the big carb (Walbro, ZAMA) can hide the cylinder head so cooling is not as effective.

shonny

Nah, mate, much more fun making the dedicated one . Also needs a hole up the middle to let the air out. Beauty of being retired is that there is time for such little projects as well.

spaceworm

I have one for motorcycles you can borrow. It has a micrometer so you can precisely time your engine also. It is a little big for RC engines, but could be modified to fit.

Sincerely, Richard

shonny

Thanks for the offer, Richard, but modifying it would really improve it for its intended use? What does it look like anyway?
Cheers, Jonn

spaceworm

It must be 60 years old at least. Used it many times during my MC days.

Sincerely, Richard

earlwb

We used to make the TDC gauges from old spark plugs. One would break off and chip out the ceramic insulator. Then put in a 1/8 inch or 1/4 rod oiled or greased. Then squeeze in some JB Weld epoxy and let it sit until cured. Then you could remove the rod and enlarge the hole if needed, but usually it wasn't a problem. Then you had a TDC gauge. You could file in some tic marks on the rod as needed too.

shonny

Great, Richard. Neat little gadget that belongs in the drawer of especially interesting gizmos. If I were you, others would only be allowed to look at it under close supervision.
Cheers, Jonn

spaceworm

I had a hard enough time finding it after my move. Likely no one else could ever had found it. Thanks for your appreciation of it. It is a small treasure of mine.

Sincerely, Richard

av8tor1977

My Feedback: (6)

I just gutted an old spark plug. My dial gauge was then a nice slip fit into the shell. I added a set screw to retain the dial indicator and, presto, I had a cool new tool.

For a positive stop, I once again gutted a spark plug, but in this one I glued in a piece of tubing with JB Weld. I let the tip of the tubing extend about 1/4" or so beyond the threads on the plug shell. This provided me with a positive stop and the tubing lets the air out while turning the engine over so you don't have to fight compression while using it. Works great and I've been using it for many years. Sorry, but I don't have any pics to share on this computer.

AV8TOR

FlyBoy95

Just to jump directly in the deep end after skimming these forums....

I have been interested in attempting to use one of these plugs in my FS (multi cylinder) engines. I have several of the Seidel / UMS / Evolution 777 engines and have reached a point where the G5 is equivalent to the cost of the OS FS plus (which when i have one go I just replace them all normally.... I replaced them individually and got to the point where id replace one idle and lose another).
I have a Topflight corsair (Giant scale gold) that I am currently modifying the plans and design for (A version that i have seen rarely at model shows, I have all the information on the specific version I want to do including Sqn postings and final resting place).
I have dreamed about putting the 777 into it, but really dont want the fuel cost with the FS (3L per weekend with the old model) and have been considering a petrol conversion.
I was wondering if any of you guys had tried converting a FS from glo' to gas? I see I can use an ignition system on the model.... but at this stage with what I want to do the additions weight (although being marginal) would throw my wing loading over.... as i prefer a light loading so i can maintain characteristics...
Some of the planned weight additions is a scale functional exhaust system, scale tail undercarriage and a scale 3D modeled cockpit (Has been designed and printed, brass shim glues and micro nails for fasteners/ going over board yes).

I am trying to find a throwaway FS that I can experiment on as I am not willing to play with my vintage FS engines that I will not convert due to age and value.
All in all my aim is to get rid of the ridiculous fuel consumption.... The cleaner running with gasoline..... hopefully removing the need for the bulky ignition modules, hall sensors and.............. etc.
All suggestions, ideas, suggestions, experience with this alterations will be appreciated! Thank you in advance