does any one know the whole size in the water flow restrictors , on 600 efi 525 s they are made to hold back water to fill header

starboard is .389, port is .406

slightly different thank you

525 : shows .406" for both sides
http://www.mercruiserparts.com/Show_...lpipe+Assembly

600sci shows the same as above:
http://www.mercruiserparts.com/Show_...lpipe+Assembly

The big question is whether to use them or not. I thought there was a Merc. service bulletin that called for them to be removed along with the bypass hoses tying the distribution rails to the tail pipes. On my 47 Fountain with triple 525's, my rear engines have the restrictors in the tails but my center engine does not. None of my headers have the bypass hoses.. sorry if this is a minor hijack but might benefit the OP too..

Hre's the bulletin:
http://www.offshoreonly.com/forums/a...der-update.pdf

That was From this thread:
http://www.offshoreonly.com/forums/g...ulletin-2.html