I need help!!!!
I run in Mexico City on an altitude of 9,842 ft above sea level an Inferno GT from Rally Game with 40% nitro, my problem is the glow plug blow up, and I see a lot of carbon deposits in the chamber and head top.
I hear that the head clearance is calculated according to the amount of nitro used, in this forum most of the categories run at sea level and 25% nitro. My question is: The higher the altitude more head clearance?? the more nitro more head clearance?? or Do I have to change the Glow plug?? I use an .21 O.S.Max with an #8 O.S. Max glow plug.
Thank you very much.
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Before I take the first step here, I have to ask. Do you know your engine's numbers (compression ratio, port timing numbers, head volume... etc.)
As to head clearance... Reducing head clearance helps to force combustion into the head bubble, increases squish velocity & can make up lost CR from elevated sleeve port timing. You can reduce head clearance quite a bit as long as you remain mindful of your compression ratio, plug choice & bearing condition. I've run heads with a clearance as low as .006" on mod'ed engines. Engines can be run with a CR in the 11:1 range, but engine longevity will suffer. best to keep the CR at 9.5:1 to 8:1.
If everything with the engine is as it should be (timing & CR) I'd change to a cooler plug, either an O.S. A5(med-cold) or McCoy #9(cold) first off. Depending on how heavy the carbon deposits are, and how many gallons I would move toward running a slightly leaner needle. But without touching the engine, I'm just guessing.