I like to know what effect prop. dia. has on performance. I have 1959 john 35 hp.I hav a 10 x13 and a 10 1/2 x 13. both fit will either one effect speed.
Both of your props have a 13 pitch which means that under perfect conditions your boat would move 13" for every revolution of either prop. Therefore, the increased diameter would give you more power for say pulling things or getting on plane more quickly, but at the same RPM, no difference in speed.
