Schrader valve for fuel pressure

I'd like to add a schrader valve to my fuel rail so I can check fuel pressure easily. Where the heck can I fnd an appropriate valve?

McMaster-Carr?

I don't know whether there are any differences in materials between a schrader valve for air vs. one for fuel...

Looks like there may be a seal material difference, but the good news is that perhaps you can get a fuel-compatible core from any auto parts store and use it to replace the one in the fitting from McMaster?

You did better than me. That's the first place I thought of but couldn't find them. Anyone know if you need something special for fuel?

I think I just used a 1/8 NPT deal from Edelbrock or Holley from the local parts store.

In reply to Ranger50:

You mean for a fitting the valve goes in? I need the actual valve though.

I think ebay may be the answer. Weird that I can't turn it up anywhere else. This look okay?

http://cgi.ebay.com/ebaymotors/Schrader-valve-w-cap-nut-7-16-heavy-duty-bulk-avail-/250653068695?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a5c164d97

GM used to have screw in (welded now) pressure taps on their fuel rails back in the 80's. They had some special pressure gauge service tool that they recommended. It was the same thread as R12 A/C fittings which IIRC is AN-3. I went to the u-pull-it and found a couple and added it to the fuel rail on my Megasquirt. I have a set of old R12 gauges and use that to check it.

The Race Place also sells them with different threads. http://www.trplace.us/

Scott

Scott_H wrote: GM used to have screw in (welded now) pressure taps on their fuel rails back in the 80's.

This is what I've used in the past. Been awhile, but they were either easier to pull from V6s or I couldn't find them on anything but V6s at the junkyard. I tapped/drilled a banjo bolt, screwed it in, and voila:

I also seem to recall that there might've been a metal cap that screwed on??

The run-of-the-mill pressure gauge I bought from a chain autoparts store fits fine...

Why not permanently mount a gauge?

porksboy wrote: Why not permanently mount a gauge?

Most mechanical pressure gauges use a brass bourdon tube that flexes as pressure goes up. If that tube leaks or fractures over time you will have a heck of a problem on your hands.

You are adding in some failure points with a huge downside when you really don't need to.

Scott_H wrote:

porksboy wrote: Why not permanently mount a gauge?

Most mechanical pressure gauges use a brass bourdon tube that flexes as pressure goes up. If that tube leaks or fractures over time you will have a heck of a problem on your hands. You are adding in some failure points with a huge downside when you really don't need to.

Fair enough. I didnt think about the Bourdon tube.

GM standard is the same as AN-4, but you need to figure out how to put the Schrader valve in there if you don't trust just using a $6 AN cap.

I've been known to weld up custom fuel rails from Ford or Chrysler steel units. Smart scavenging will get one with a test port on it. Ford's different from GM, or rather, GM is different from everyone else.

Of course McMaster-Carr has Shrader valves wi/ pipe threads on the bottom!

In reply to motomoron:

Yeah, they do, but they specifically say they're "air fill" valves. I don't know enough to say if it's a problem or not, so I just felt better with something that said it was for this application. I ordered the one from ebay. I'll look it over real good when it gets here. I have several fuel rails for this car so I can give it a shot and not be out anything if it doesn't work out.

Thanks for all the posts here. Learning a lot.