yea i painted an engine trans combo up all purty once.....
upon reassembly it wouldnt start unless i added the aux ground strap
i even had to add one from the alt to the v/c
the paint was hindering the grounding,so i always add extra grounds
thats important also if you have electric guages
if the engine isnt grounded good,the guages will read erratic
sometimes you can "see " a bad ground
watch to see if the speedo needle jumps upon cranking
if so its trying to "find" a ground thru the very fragile speedo head
too much of that,and its toast