Finally going to install my Langdon HEI I bought eons ago for my 55 3200 with a 235. In the instructions it says to set timing at 10-18 degrees BTDC before dropping in distributor. I located the ball bearing and pointer and lined them up for TDC. My question is approximately how far is the bearing offset from the pointer to get the 10-18 degrees ( 1/4" for example) I don't see any degree marks on the flywheel. Any help appreciated.