I am about to break in a murnan +12 sct. I use 30% nitro, do I need to shim this engine out. If so, how much?

Since it is not a standard engine, and has been modified by Uriah I think you should ask him.

AFM

Hi Joe. You should add one .1mm shim at least where you are. I believe the engine is still stock. If you only see one .3mm silver shim under the head, you should add a shim. I have ended up running .2mm above stock in Florida.

.1mm shim should be fine.

hey guys
wats a good glow plug for a novarossi race .21 running 25%
the engine came with a RB 6 plug so im after something same as that

thanks
John

for offroad stay with the no. 6......

for onroad go with no.7

its for onroad thank you!

It really depends on the weather for that day of racing. Manufacturers include a plug to get you started with the motor, however it is expected that you change the plug according to geographic location, temp, humidity, etc.

Quick question

For very cold weather...... 6 deg C

Increase head clearance or lower?

Hotter plug or colder??

Cheers

hotter plug.........7C ou 6F for .21 onroad........

and 5 for .12 onroad or .21offroad........

regarding the head clearance, I wouldn't change, anyway theoretically you should increase head clearance due to the higher content of oxygen in the air (lower the temp = higher the density of the air, which means you have a bigger volume of oxygen for a given volume of air compared to higher temps)...

you just need to run the engine rich, and this is why you need a hotter plug, to achieve a complete combustion...........

I think I'll try increasing the head clearance as the air is denser at lower temps so more compression. I'll see how it runs first but deffo on the No5 plug

Cheers

hey guys i got a novarossi based max power .12 sl3 engine, it a awesome engine just the prob is it needs a change of conrod and i cant seem to undo the head, the head bolts are for a flathead screwdriver which is very unusal, has any1 encountered this problem and what did u use other than a screw driver to undo it got me stuffed cheers kosta

all nova based engines uses this philips screw. we all normally changed it to 2.5 socket head screw, as i have a very very bad encounter with this nova screw, as the head of the screw snap off, but luckily, it still show a tiny bit where i can use my fingernails to turn it out, phew, else, need to get a new crankcase.

umm do u mean flat head screw

ALL Novarossi based engines have flathead screws. I don't like them much either. Make sure that you use a GOOD screwdriver with a not too small blade and apply it absolutely vertical to the screw.

Once you got them out, you can change them for hex head screws from Picco /Mega/LRP.