Agree, plenty of seasonal racers use/prefer O.S plugs in the Novarossi engines. Plus i have surplus O.S P3 plugs and Zero novarossi plugs.
The noise has stopped, still not 100% sure of what it was as the top of the piston had no evidence of 'Knocking'.

This has been a long standing debate...
The OS plugs have a different taper at the end. THey don't seal tightly in a Nova head button. If you crank on the plug when you install it the head button will distort the head button and Nova plugs (or any other manufacture) will not seal properly. SO no it will not destroy the engine, but it can distroy the head button.

Thanks for the Helpful info will keep a close eye on the seal between the Button head and plug.

Can anyone please confirm that the arrows on the bottom of the cooling fins and button head face forwards or backwards.

And if they were facing the incorrect way could it have been causing that mysterious 'Knocking sound' i was hearing before.

Thanks.

it faces the rear.. not sure it would cause any sound or any performance difference though

I have them both around the wrong way…..

Thanks.

the head doesn't matter much and the arrow on the underside of the cooling head is just an imprint from the button

Keep in mind this ONLY happens if you gorilla-tighten it.
If you tighten the plug up only just perfect, no problems!

The reason I prefer the OS P4 plug rather than the C6tgc nova, is that the OS plug is more consistent. Higher consistency between plugs.
By that I mean you run nova plug, change to new plug, and the tune is wildly different as a result, it's as if the nova plugs have a great variation between one plug and the next.
The OS plugs at least seem much more consistent, and more the same.
Also I find it a lot easier to tune, I am assuming the P4 might be slightly warmer than the C6, so that might be why.

If you want to run an OS plug in your nova, you should run the P4, at least that's what I like best, I think the P3 is too warm.

tight rod

Thats wat i meant no destroy the engine. Think logically b4 saying it was the engine lol

I just noticed this comment and just wanted to say:

Please stop posting misinformation like this.
This discussion has been done to death. Persons seeking to end this string of misinformation actually measured and posted photographic evidence that:
-The angle of the taper is 100% identical
-The length of taper is smaller on OS and bigger on Nova plug
-Therefore the actual taper is the same
-However due to the lesser area available for seal to occur in head button, you must be careful not to overtighten it, since there is a smaller section of taper pushing on the head button material.


So, in conclusion:
PLEASE STOP SPOUTING THIS RUBBISH THAT THE TAPER IS DIFFERENT. The angle of the taper, meaning "THE TAPER", is _THE SAME_, so please stop it with this regurgitation of misinformation.

Hence there is NO REASON, ZERO REASON, why you would destroy the sealing ability of the headbutton as long as you do not severely overtighten.

AS such, I have no problem running OS plugs in my Novas, and everyone else I know do the same.

Thank you.

well in essence the taper is different, one has more surface area than the other, you took what he said as taper being different to mean angle...

Well said, and thanks for clearing that up.


The length of the taper being shorter on the O.S. plug does not mean that the taper is different. It just means that the O.S. plugs are shorter than the Nova plugs, which, in turn, means that when you tighten the plug in the head button, the coil will just sit slightly higher than the coil of a Nova plug.

Does that mean you will replace every head button that gets damaged from your answer ?

At least some are trying to warn people of possible problems.

I would never put a OS plug in my Nova Rossi engine because of the reason mentioned amongst a few others.

Thank you keyboard cowboy...I'm sorry about the misinformation I was spreading, thanks for clearing up all the bad info I have been spouting off.

For what it's worth I'll just keep on running my Nova engines with my Nova plugs tank after tank after tank...do you know why? I'll tell you why, my engines DON"T FLAME OUT! 4 years, 2 engines, only running Nova plugs (mostly C6 plugs), never a flame out and I don't run a safe, fat, gargling tune. But to each his own.

back to our regular scheduled program.

I agree that it is logical to run Nova plugs in a Novarossi engine, but I don't think it's necessary to say that O.S plugs in a Novarossi engine will destroy the head button. I probably would never run an O.S plug in my Novarossi (if I owned a Nova) too, but it wouldn't hurt to use an O.S plug in it temporarily if that's all you've got. I think we're just missing the point of the original debate I in no way meant to start a flame war on thsi thread but it seems the argument was left up to interpretation rather than making the details clear. Carry on