One thing here is that both valves are closed twice once in the exhaust stroke and the other in the power stroke both times at the top of piston ,You have to keep an eye on the intake valve and when that starts to close and go TDC that is the TDC mark You need to time off of , many guys put the dis. in 180 degrees off because they are timing off the wrong piston TDC and You have to turn engine in the same direction it runs . Hope this helps.
Pete
