We have a gravity floor furnace and there was a little cap over the pilot light. This cap is missing and we need to see where we can purchase another one. I assume that we cannot light the furnace with this cap on?

Have you tried lighting,, it will either work or not work

Not sure what cap you are talking about. But am assuming it's the little 1 inch round sight glass cap at the top of the heat exchanger close to the floor grate. That covers the hole in the heat exchanger that allows you to light the furnace pilot light from above. If it is missing you will need to replace it before using the furnace. And you can find it or should be able to order it at your local havc supply house. Or lumber yard might be able to order one.

He said it was over the pilot light, don`t think that would be the sight glass