hpi apollo

plug length doesnt matter for nitro, a hotter plug is a thinner element which lights up earlier causing more advanced timing, and vise versa for a colder plug, for 20% nitro an mc-59 should be fine, and there is no need to run 30% nitro in an engin like that, you should only run 30% in race engines, otherwise you are paying more per gallon and not getting that much of a use out of the extra nitro, for higher nitro you need to lower compression by adding a head shim, more nitro needs a cooler plug, and they arent called spark plugs, they dont spark, they are glow plugs (they glow bright orange) also, DONT USE THREADLOCK ON THE ENGINE HEAD, EXPECIALLY RED LOCKTITE!!!!!!!!!!!!!!! never use red locktite on anything on an rc, red is way too strong, you should use locktite on heads anyhow, the screws cook themselves in place, red locktite will make ti so tight you will strip your screws then you will have a big problem on your hand, just use the search button and you will get results quicker, also, next time dont post a thread like this in the fuel forum, post it in the engines forum