jefx

I just picked up some Odonnell plugs for my Mach .26 and was wondering if any one else has tried them.

They are made by Dynamite and are rated as Medium/Cold heat range for .21-.26 engines. They sound like a perfect match, but I haven't tried them yet.

I have been running O.S. LC3's in my Mach 26, and the engine has been running great. It just keeps getting faster and always runs in the low 200's. I realize that it is a hot plug designed for the Tmaxx, but my LHS has been back-ordered on MC 8's for a long time now. I can blow away a 2.5 Tmaxx even when it has a head start.

I realize that the heat range of a plug determines the timing of the combustion, but what is the real advantage of running a cooler plug in a big block engine? Is it better for the engine to have a slower combustion timing? Right now I don't see how this engine could run any better than it is, but I will try cooler plugs just because people recommed that you should.

So has any one tried this plug? And why should I use a cooler plug in a big block?

ThermalRD

Which o'donnell plug are you referring to? The odonnell 99? Or the new Monster Truck plug. I read in one of these mags here that odonnell has a new plug for monster trucks with larger motors now. Your HOT OS plug should be fine in that Mach .26. I believe the manual recommends the HOT MC59 plug. Colder plugs are usually used for the hotter weather, and higher nitro content.

Matt

jefx

On the plug there is a number "99" engraved on it, so I'd guess that would be the one.
The package says
"O'Donnell 1/8 racing glow plug .21-.26........Medium/Cold heat range.........Dynamite". That's it.


Why is that? Does the higher nitro content have a lower flashpoint which would result in pre-detonation when using a hot plug?

What about the weather? How does that affect the heat range of the plug?

I've read where many people recommend cooler plugs for big blocks all the time, that hot plugs are hard on big blocks. Is that true?

ThermalRD

Jefx, i've always been told to use a cold plug in these larger motors. Recently i've been reading the manufacturers are recommending medium, and even HOT plugs. Like the Mach .26. It seems to me its gonna come down to what runs best, and doesnt over heat. Its funny how Odonnell is releasing a plug for all large motors, that only comes in one heat. This glo plug mystery sorta reminds me of the breakin processes. Years ago i was always told to keep an engine really cool during breakin. Then they said to get them to atleast 180-200 during breakin for proper expansion. Now you'll read some manuals reccomending a wide open throttle breakin. For me, medium to HOT plugs work best in the winter. Without them i can hardly get my truck started at the track in the long winter months. Summer time i find the cold plugs work better, or a medium. I guess you could use a medium all the time. I dont really know why Dynamite says to use the MC59 plug. I will have to try one this weekend and see how it runs.

Matt

Johnny Ripper

My Feedback: (3)

good thread[8D]

HOLMES

I have ran a odonnell 99 and a mc59 in my lst . The manual calls for a 59 but I didn't notice a difference. I did have to retune my engine. And the difference with the engine break in know is the materials that are being used .

greig

Glad to see you approve bashmaster just dont add anything and stuff it up!

I have been running os a5's whith a lot of success, However I'm not sure if this is the ideal plug for the mach 26 it was all I could get hold of here in Tasmania down at the a##hole end of the earth!

Anyone else useing this plug?

jeffx do you know where in the heat range the os a5 compares to the o'donnall you are refering to?

jefx

I believe the O.S. A5 is a cold plug. It's also a short plug.

I don't like using short plugs, because it reduces compression. Since it's shorter, the combustion chamber actually becomes larger. The ODonnell, LC3, MC 59, MC8, and MC 9, are all long plugs.

Since this thread, I actually went back to the LC3 plug. My LHS doesn't carry the ODonnell's, and I didn't really notice much difference in performance from it.

greig

Jefx . My lhs only stocks os plugs , what plug in their range suits the lst, Do you know? Thanks

PeteOz

Greig:

I have run a few different plugs in my Mach 26, but the OS 8 is running SWEET! Stick with it

RC_UK

Im using the Novarossi No. 5 works well for me , but its probably colder over here in the UK

icenutz

I used the OS * also throught the fall weather here in PA. It ran great and the engine tuned great. The MC59 was running way to hot for me.

Eracer76

What fuel are you using? Ive heard that with more nitro, you need a colder plug.
I used 20% Monster HP for about half gallon, breaking it in. Now I switched to 25% Monster HP, still using MC59 plugs and it has been running hot. Its cold here in the Chicago area too! So, I tried putting in a new Duratrax gold plug (short cold plug) that I had in my box (the Savage likes them) and its a little better.
Id just like to find a plug thats the right length, works good and doesnt run hot with 25% fuel.

icenutz

I use the Dynamite Blue Thunder 20% fuel. When I used the MC59 i could not get my temps down and was burning the top of my pistion. I switched to the OS #8 and I have had no problems since. Outside temps when running it were around 50-55 degrees and my engine temps aroung 215 degrees. I have not run my LST since November. I usually do not use them in the cold of winter.

Eracer76

Thanks ice, I think I'll try that OS #8 then!

jefx

I've been using the O.S. LC3 plug. It's a long hot plug, equivelent to the MC 59 (Which Dynamite recommends for this engine). It appears that everyone has their own opinions on this topic, so just use whatever works well for your engine and driving conditions.

greig

What are the engine charachteristics useing a cold plug and for a hot plug?

smashn

Im glad u brought this up jef i had issues with switching plugs!!! I went from a 59 to a mc9 on my last outing (partially due to the mc59's goin out in one tank....could be my old tuning habits???????))) it took forever for me to get the truck to operating speed but when i did it seemd the mc9 was waaaaaayyyyy better even in the colder evening weather!!!! MC59 was running way to hot and would go out at the same settings the mc9 was dead on.......was runnin right at 200 degrees with the mc9 too! jus my observation but i think the colder plug works well nd is a lil more forgiving to newbs.....like me......seems the hotter plug needs closer moderation! I was wandering has anyone had the same results with the 2 plugs?

ringneck

i used the odonnel plugs when i first got my truck and they didnt last very long and they are exspensive so ive been useing os lc3 and its been working good for me. but every motor runs different in different climates and tuning prefrences.