vacuum pump line

Will changing from a 12an to a 10an vacuum pump line affect the pull it has on the motor? I need to move to the smaller fiitings due space constraints? The vac is controlled by a moroso relief valve.

Yes, it will effect the amount of air that the pump can flow. The smaller the line the more drag on the pump, but the -10 will probably be fine though it will flow less air. Do you have one or two lines to the motor? The motors size, horsepower level, power adder, ring package, rpm, and fuel type all determine the airflow needed by the pump. How much vacuum do you like to pull and how far open is the relief valve?

c headed 632. q16. low tension rings setup by Jet Boat. no power adders. just one line from a valve cover. might move it to pull from the valley pan on the intake. I adjust it to pull almost 10lbs on the gauge

Most companies will advise you to go to two -10 lines or stay with the -12. With a low tension ring package on that large of an engine you need to be able to evacuate lots of air. Is there anyway to clock the pump differently to keep the large fittings? Just a thought.

May have do a little clearancing. Probably shouldn't change what is working.
Thanks you Mr. whatbumper!