Using AN Fittings to plumb motor

[BrendellaJet]

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?

[flat broke]

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

[steelcomp]

You don't need -8 for the headers. They don't flow that much water, nor do you want them to, and I wouldn't consider them for part of the dump system AFA volume. Your overboard system should work adequately regardless of header water. I'm learning from these boards that you can't have too big an overboard line, especially if you don't regulate your pressure. I'm going to -10 for my overboard line.
The holes through your motor plates can be 3/8" tapered pipe, and use an AN adapter fitting (3/8 male pipe to -8). Just drill them as close to the center of the passage in the block as possible. The -8 lines will be adequate for inlet. I fill my block from the bottom at the drain plug holes, not the front of the motor. Others will tell you it's not a good idea...I've never had any problems, and my block dosen't fill with sand. I believe it promotes more even block temps. :coffeycup

[BrendellaJet]

Awesome. You guys give me a couple ideas. Ill have to think about it, although the idea of using the adapter w/oring seems like it will be easier on me...As far as block pressure goes, Dave wants me to run a guage. We're pushing the envelope on the compression, so I want to keep an eagle eye on the pressure. thanks guys.

[superdave013]

I like your idea of doing it AN (with O ring) and not pipe threads. Pipe threads are tapered and you will always see some threads on the adapters. If you thread it for the straight AN and kiss it with a counter sink lightly (for the o ring) it will look super sano. The AN adapter will seat all the way to the flange and no ugly theads will be seen.
Plus no one is really doing that with off the shelf water inlets (yet) and yours will look slicker then the dude parked next to ya.
just my 0.02

[BrendellaJet]

Aha! Then its settled. Ill give you a call when Im ready to plumb!

[steelcomp]

Look...no fittings at all!! http://www2.***boat.com/image_center...729bah_eng.jpg

[BOAT ANCHOR]

I like your idea of doing it AN (with O ring) and not pipe threads. Pipe threads are tapered and you will always see some threads on the adapters. If you thread it for the straight AN and kiss it with a counter sink lightly (for the o ring) it will look super sano. The AN adapter will seat all the way to the flange and no ugly theads will be seen.
Plus no one is really doing that with off the shelf water inlets (yet) and yours will look slicker then the dude parked next to ya.
just my 0.02
There is a tool that is designed to machine the O-ring pocket into what ever a straight thread/O-ring AN adapter is going to be used in. It's called a "port tool" and comes in different dash (-2 to -32) sizes. It looks like a spot facing tool, except it has a radiused step ground in it to create the correct sized (diameter and depth) O-ring pocket for the particular AN size it was designed for. The tool also spot faces an area for the hex portion of the AN adapter to seat aginst, and reams the hole, to the correct size that will be threaded, for the AN adapter to thread into. So it spot faces, cuts the O-ring pocket, and reams the hole to correct size for threading, all in one opperation. They are a little spendy if you purchase them new, but they pop up on ebay all the time and usually go from $1.00 - $15.00. Dave is right, a flush fitting AN adapter looks much better than an AN adapter with exposed taper pipe threads and white Teflon tape or sealer.

[Cs19]

Just learn to use a pipe tap and go 3/8 on the plates.Once you learn your taps its a piece a cake.

[BrendellaJet]

Next question- is there a difference in types of taps? Ive got a pretty good collection of them. All apper to be tapered at the tip, not sure if thats the taper you're referring to...If there is a difference, how do I tell the difference between them?
CS-any pointers on using the pipe tap? can you please clarify also-3/8 thick plates, or 3/8 hole (6 AN)???
Sorry for all the rookie questions-thanks for the help!