Larry is right. If your timing is off 10 degrees,due to a worn chain,you need to install an offset Woodruff key on the camshaft. I experimented once with a 1967 200D and set the timing off by one chain link-(that's 18 degrees). The valves did not strike the pistons until a speed of about 50MPH. Luckily, no damage was done. I would not do that again. Use offset keys, or replace chain and cam gear.
Bill Lewallen Lexington,Ky.