No
The 3aj does not need battery power to run. If you have a spark, any spark, that should be ok.
Since you just replaced the head, make sure everything is connected and installed allright, valve timing ok, fuel arriving at the carburettor (with the fuel pump this can sometimes be a problem!), idle mixture set correctly, idle speed set correctly etc.
Give some more info, we might be able to help.
Auke
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