What is the distance between connector J8 and J9 in Max 10 board EK-10M08E144

You could refer the measurement at MAX_10_10M08_Eval_Kit_Board_RevA_12Aug14_1_16.5.brd file. This can be download at https://www.intel.com/content/www/us/en/programmable/products/boards_and_kits/dev-kits/altera/kit-max-10-evaluation.html > Table 2. MAX 10 - 10M08 Evaluation Kit Documents Available ( Complete kit document installation )