Or anyone who might know….I did a top end rebuild of my 66 6T ( unit 650 ) and I’m at the point of starting the engine for the first time. I only removed the head and barrels, the crankcases weren’t split so the cam timing wasn’t changed. So With the ignition timing set, valve gaps checked and reset, fuel in the float bowl and spark present, she wont start. I can smell petrol ( no leaks ) and the plugs are dry so it’s not flooding. Every now and again it seems like it’s trying to start but just wont catch fully. I’m wondering about the sequence of the valves opening and closing. the whole suck squeeze bang blow makes perfect sense and I set the valve gaps by the book. Why won’t the fucker start. it was running before the rebuild. I’m stumped.