Checking the distance from the back of my engine mount to the prop washer is about 1/16 to 1/8 inch short of 6 1/2 inches.
The Pitts manual shows them using 2 pieces of ply between the firewall and the engine mount with a US 41, was this just for that setup? It also looked like they had an old style firewall.
Can I use a thin piece of ply to get the prop washer to 6 1/2 and does it affect anything if the distance is more than 6 1/2?

Steve