Technical Thick Spark Plug Washers?

Got some trick aluminum heads for my flathead, but noticed the stock 1/2" reach spark plugs left the gap about 1/8 in the hole. So I got some recommended 3/4 reach plugs, and was rewarded with closed gaps and cracks from valves hitting the longer plugs. Does anyone make a 1/8 gasket for the 14mm thread, 3/4 reach plugs? If not, could one use two 1/16" copper washers?
Thanks for your thoughts
Abe

 

Back when they thought it was important to have the plugs indexed in the cylinders, two copper washers was the normal operating procedure. Gene

 

use two or three gaskets

 

You can still buy indexing kits or washers from your favorite catalog speed shop.