drill, tap hole size for Yamato 302 cooling?

[halestorm]

While I have the power head off my y302 tower, I thought I would add a hole in the back of the tower I've seen people use to facilitate flushing and cooling with a small electric bilge pump. This is where I'd put that hole, right? And what size? It seems someone once told me to use 1/4 NPT but that requires a 7/16 drill -- that's a pretty big hole! The hole I'm meeting up with is about 5/16 in diameter.

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[champ20B]

What you'll need is for the inside diameter of the fitting to be as close as possible to the inside diameter of the cooling tube. A 1/4 NPT fitting is about right I believe. You might want to go all the way with a 1/4"-5/16" bit to the tube, then finish with the bit needed for the fitting not all the way, but enough to thread the nipple/fitting into.

[hydroplay]

We always use 1/4 inch pipe threads with a #6 AN fitting and cap on Yamato stuff. It's quick and easy to remove the cap and attach a cooling hose to test wheel. Best pics I can find quick.

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