Setting Squish on Brand New Engine

[AzMandella]

I have a Nova 21M Keep that is brand new . It is so tight you cannot turn it up to and or over TDC by hand . How would you go about measuring head clearance ?

 

[Danny King]

You should be able to top dead center it assembled and set the clearance to .012-.015” run it till it loosens then set it where you want it.

 

[RaceMechaniX]

Use a heat gun or hair dryer and warm the cylinder up with the piston resting at BDC. Add some oil to the cylinder and turn over till the rod goes over center.

 

[Mark Anderson]

Old pylon trick. Make a 100/1000 shim to fit under the liner. Make all of the measurements with the shim in and subtract the 100. That will put the piston below the pinch point.

 

[SayMikey]

If its the motor you got from me it just needs broken in all the measurements are correct. Hair dryer or heat gun and run it rich on the beach real rich to the point that fuel is the coolant. do this with 2 tanks of fuel then put it on the water slightly rich. Run the boat hard halfway down the straight and slow 3/4s of the lap. Do this a couple times and let her rip///IMHO

 

[AzMandella]

No it is a brand new 21M that I bought from Novarossi Usa . I also have a brand new .21 T21 5M . The 5M can be turned by hand 360 degrees . It is tight at the top but it can relatively easily be turned . The new 21M is nearly impossible to turn over by hand .

 

[BrianNeumann]

A great tip some one told me a while ago when running-in a new engine, & just to prolong its lifespan is set the piston to BDC immediately after you shut it off. To prevent scratching the piston/liner & keep the piston from getting stuck at TDC while the engine cools. I’m sure many others already know this, but at the time it never crossed my mind? So I try to pass that tip along to anyone listening. All 3 new Nova .12 engines I have bought, especially the On-road Car versions were almost impossible to turn over by hand due how tight the tapered fit is initially. I keep a wrench nearby in case the piston sticks at TDC during start up & break-in. If you hear a squeaking noise, it goes away after 5-6 tanks in my experience. Like others already mentioned, preheating the engine, a rich needle while making sure the engine is building good heat is critical. My .12 engines didnt really begin to loosen up until I have burned close to a gallon of fuel through them. Like many others mentioned. And starting the engine with the glow plug loosened up slightly really helps relieve compression and spin easier. then snug it up once it stays running. I always start a cold engine with the plug loose after break-in as well. All of these suggestions and the ones above have really helped me with getting through the break-in period, Good Luck & be patient!
Brian

 

[James Schmidt]

Marvin, I broke in that motor I sold you relatively in the same way as suggested above. Just keep it heat up with a heat gun for the first couple of tanks on the bench. When you put it in the boat run it without cooling run it rich as it won’t get on the pipe you want the fuel to cool the engine the same is on the bench.

Once you get about three or four tanks through it in your boat running on the pond without cooling with a rich setting. start leaning it down so it comes on the pipe on the next 3 tanked but only do wide-open throttle down the backstretch then will do a lap and let it cool. Then down the back stretch wot and do a lap while it cools. Bring it in let it cool always put piston at BDC while engine is cooling off. Now add water cooling. Repeat steps but a little at a time more pro long throttle.

I would suggest you get some 30% with about 23% oil no sense in burning 60% nitro for a break-in it could take a gallon of fuel before it’s ready to go.

Always heat motor up very hot before running. cold is not good

You will find when you run it on the bench that when you heat the motor the pinch slowly loosens up and you can turn it by hand when the motors good and warm

Thanks
Jim