Fuelman
Posts: 1039
Joined: 12/31/2001
From: Jordan,
NY, USA
Status: offline
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quote:
need some advice Fuelman. I am breaking in an OS .21 RG in a mayhem. i ran two tanks leaving the buggy on the starter box running very rich but reving the idle up and down. then i leaned it a bit on both screws and drove it around bliping the throttle and progressively loading it harder and harder. each tank i leaned out the high end screw a little more and waiting a bit between tanks to cool down with piston ant BDC. Problem is i cant seem to get the temps up beyond about 150. Ive gt the motor running pretty well now and it simply doesnt want to heat up. I am concerned about leaning it too much. Any info on needle settings on the RG on a broken in engine?
Like 46U mentioned, there is no hard and fast rule for needle settings. When you run it, take it to wide open throttle on a good long stretch and listen! If the engine goes to wide open and then sags or starts to loose power, the high speed needle is too lean. Richen it up until that no longer occurs and then back off a little more for added insurance.
If you are transitioning to wide open and it has a real hard time speeding up and stumbles and never quite comes up on step, it is too rich.
Same thing goes for idle and transition. The low speed needle has mixture influance all the way to 3/4 throttle on most engines, so it is very important to get the low speed needle adjusted so that the off idle transition is crisp and clean. If the engine starts to speed up then fades real quick or dies, it is probably way too lean on the low speed side. If the engine stumbles and stutters and has a hard to clean out and speed up it is too rich. Always adjust the low speed needle in small increments, like 1/8 turn at a time or so.
Whenever changing types of plugs or fuels, both needles can be affected, sometimes a little, sometimes a lot.
Keep in mind, that all this is done without regard to temp, it is done by hearing and "feeling" what your car is doing.
I know in previous posts, I mention target temps, yes, that is for many engines, not all in the car world. Once a temp of 230 or so is reached (at the base of the glow plug) on most ABC type engines, the sleeve has achieved designed fit to the piston where friction begins to be minimized between the piston and sleeve. This design fit range of temp can extend to well over 400 degrees in many engines, of course it all depends on a bunch of variables.
No two engines are going to have the same target temps due to literally dozens of variables. One thing is for sure, if you are only getting 150 at the base of the glow plug after it is tuned for maximum performance, your engine has too much cooling capacity.
I have cut off cooling fins of several heads to make them run hotter (i.e.: closer to normal) because they were over cooled and had very fast wear rates. Remember; heat makes horsepower.
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Fuelman
Cooper Fuels LLC
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RE: Nitro Engine Care And Breaking In/Starting Instru... - 
This will help people who are new and want a good vid.
