Tell tale question

[2quick4u]

I have a 1988 mercury 90hp 3cyl. The dealer says the tell tale fitting where it connects to the cowl is un available . I was going to machine one on my late like a bulk head fitting. Does the size of the hole make much difference- affect cooling or water pressure? Does anyone have one of these late 80s motors they could check the ID of the tell tale with a drill bit.

[the ol man]

minnow is right size dont matter, you can just run a small hose thru the hole without making a fitting if you dont want 2 go 2 the trouble,, its only on there to show that your watter pump is working, make shur the stream is solid with no bubbles in it or your pump may need attention,, good luck..