Siphon Pump Line Diameter
 

Anybody know what size the tubes going to and from the Siphon Jet pump are? I've made my own orifice restrictor setup and just need to know what suze fuel line to AN adapters to get. My 3/8 adapter seemed to large so Im guessing 5/16 or even 1/4?

Any help is appreciated.

5/16" according to my notes. What's the story on this custom orifice? I couldn't find any info on the stock orifice size, but I stopped worrying about it since I've been running 3 bar fuel pressure for about 10,000 miles with no tank transfer issues.

Here are instructions from RSI on how to make your own venturi.

Buy a -6 AN Y adapter. Tap one of the legs and install a set screw in it. Drill a small (5/64) hole through the middle

The plumbing is fairly basic. You have 2 feed ports on the hanger and 2 return ports. Just make sure you know which ones are which before installing it into the car.

You come out of the hanger with -6 AN lines. You install your Y block in one of the feel lines and the restricted leg of the y will be connected in to the feed line side leading to the passenger tank. This should be the smaller of the hardlines. The other leg of the Y along with the uninterrupted -6 feed line will go to feed you fuel rails. Plumb one of the return ports to the regulator return and plumb the other return port to the return side of the passenger tank.

Thanks Ed. I ended up buying a vibrant 4an-1/8npt restrictor with a 4AN to 6AN transition until I get around to designing and machining a billet orifice adapter. The diameter of the lines above the fuel filter is what I needed so I can buy the adapter fittings to mate the new RSI hat to the siphon feed and return hard lines.

the nylon lines are 5/16 (to jet) and 3/8 (return).

Get anywhere with this?

I used a fore innovations Y block that has dual 10ORB-6AN fittings for my feed and siphon line. I tapped one of the 10ORB-6AN fittings with a 1/8 NPT tap and screwed an aluminum 1/8 NPT plug into it and then drilled a 5/64" hole in the plug. 5/64" orifice complete.

You tapped the 6an side of it and just run the plug into the hole?

I bought 2 6an plugs, was going to weld them together and drill straight through them and just have a union on one side to connect to a y or t block, and the hose end to go up to the hardline up top.

I tapped the 10ORB side so that I didn't damage the sealing face of the flare.

Just ordered a y block from fore to do the same lol. I think that will be less cumbersome than what I was going to do as I would have needed a y block anyway

It's very easy and can mount right where the original fuel filter used to be.

Not sure where I will mount it yet. That is not a bad idea though. I plan on running the feed up through the rocker though where the return line already is. I end up doing a 180 back towards the hat and down to the rocker channel.

What is nice is it at least has a hole right through the block for the mounting bolt.

Yup, I just use an M6 socket cap bolt right through there into the original fuel filter location. I run a 180 off the Y block into my fuel filter and then through the rocker up to the engine. It makes it easier to get the siphon line up over the transmission as well.