Headlight Bulbs Blowing

[otis71]

Having trouble keeping bulbs from burning out in a 6v system. I ran a dedicated ground to the front end and current going to the battery isn’t excessive. At first I blamed modern cheaply made bulbs but I sourced nos Westinghouse bulbs and the first one only last a couple hundred miles. The ignition switch does have a flat spot on headlight setting but if it was losing micro contact I would imagine I’d notice it in the engine. Any ideas on anything else to check?

[tfburke3]

I think a check of system voltage at high rpm might help.
Tom