if i read your post correctly this engine was rebuilt 3 yrs ago and #1 hasn't fired since that time.you also say that there is no valve noise.perhaps it would be a good idea to do a cold leakdown test and see if the valves in #1 are leaking.it is not uncommon after a rebuild to find a lifter stuck or that the spacing shims need to be replaced with smaller ones.if lifter wide open and filled with sludge not allowing valve to close all the way or when head resurfaced old spacer shim too big.[if valves making a little noise at least you know they are closing] good luck david poole european performance dallas tx.