More no spark Merc 800 s

" Followup to my 1970 80hp Mer

" Followup to my 1970 80hp Merc/ Thunderbolt ign.

Compression is good on all 4 cyl. It only started with 1&2 not running ( when I was told it was the carb) but now no spark on any cylinder.
I was wondering what the logical path of a spark might be, so I can see where the breakdown is. Kind of like
Key to battery, battery to X, X to Y, Y to Z, Z to sparkplug. If that makes any sense.
I have the Mercury Manual, and the Clymer's manual. Neither one works this way, they just have a bunch of different tests.
Since I suspect more than one problem, I figured if I could track the whole system in order, I could replace all bad parts, instead of doing what the marina did, and fix one part, but not the cause of what made it go bad.

Thanks "

" Are u getting spark to your

" Are u getting spark to your plugs? check that first, then check dissy cap and rotor and clean up the heads with a bit of sand paper, it may just be that they are dirty, spark flows through line of less resistance. then check if you have spark. if not test your plugs and leads from some other source just to make sure that that is not the problem. "