I have a 235 straight six. When I bought the truck it had a lot of chatter. So I pulled the head and had it rebuilt and replaced all the pushrods. 6 of them where bent. Bolted all of it back together and I can't get the truck to start. It does have a different carb(no manuel choke) replaced points and condenser, cap, plugs and wires. It does get spark and occaissonal back fire but still won't start.I was wondering if the timing could be out or is it possibly in the carb.