When checking the spark on my 1978 15 hp seahorse I removed plug #1 and the engine dies, When I do the same to plug #2 there is no visible change in RPMS. When testing both with spark plugs in wires against ground both have good spark. The engine will run on either cylinder if you disconect one of the plug wires. Why would the #1 make a change and cause the engine to die but the #2 does not.... The engine at this time is not running at idile. I have rebuilt the carburator but it made no difference. Any help would be appreciated
