Made a set of motor plates (rail kit) that capture the water pump inlets. Need to drill the hole to allow plumbing of AN fitting. Anything tricky about doing this? How does it seal? Are the threads tapered or is there an o ring involved ? What size is good? Need to have plenty of capacity to keep block cool. I was planning to have 2 8 AN's exiting the block, one for the headers, the other for a dump...Anyone see a problem with this?
The only potential problem you will have is if you run a pipe tap too far down into your hole. Pipe threads are cut on a taper and if you were to run the tap all the way down, you might have sealing issues. If your plate is .375", you don't want to bottom the tap out because you might not be able to get the pipe threads on the AN adapters to snug down. So tap the hole a little ways, then install the fitting and check for a good seal. Once you have a good depth/taper that allows the fitting to seal down good, call it a day.
Ooooor, you can get a straight AN adapter which doesn't have tapered pipe threads but straight cut threads and seals with an O-ring. Going this route you wouldn't have to wory about botching up the hole by going too deep with a pipe tap, but the straight AN adapters are sometimes harder to find. The only negative I could possibly see to going with the Straight AN adapter is that you have the issue of the o-ring to check up on every once in a blue moon.
Either will work, just take your time. As for line sizing, pay attention to your incomming capacity and your outgoing capacity. You don't want to be in a situation where you might be building too much block pressure. Dave will probably want to see something along the lines of around 20 PSI at WOT.
Good luck,
Chris