Schrader valve thread size
04-05-2011, 09:02 AM
#3
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
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It's a TR-6 Schrader valve, 8mm OD (nominal).
The OD thread is 0.305" x 32tpi, the ID 0.209" x 36tpi.
The metric thread dimensions are often listed as alternatives (7.70mm x 0.794mm pitch, and 5.30mm x 0.706mm pitch)--do not be confused by this, they are just metric conversions of the actual English unit dimensions.
The OD thread is 0.305" x 32tpi, the ID 0.209" x 36tpi.
The metric thread dimensions are often listed as alternatives (7.70mm x 0.794mm pitch, and 5.30mm x 0.706mm pitch)--do not be confused by this, they are just metric conversions of the actual English unit dimensions.
04-05-2011, 09:14 AM
#4
3rd Gear Member
Join Date: Feb 2008
Location: Delaware
Posts: 801
It's a TR-6 Schrader valve, 8mm OD (nominal).
The OD thread is 0.305" x 32tpi, the ID 0.209" x 36tpi.
The metric thread dimensions are often listed as alternatives (7.70mm x 0.794mm pitch, and 5.30mm x 0.706mm pitch)--do not be confused by this, they are just metric conversions of the actual English unit dimensions.
The OD thread is 0.305" x 32tpi, the ID 0.209" x 36tpi.
The metric thread dimensions are often listed as alternatives (7.70mm x 0.794mm pitch, and 5.30mm x 0.706mm pitch)--do not be confused by this, they are just metric conversions of the actual English unit dimensions.
Is the gauge electric or mechanical? If it's electric, you'll need a 1/16npt to 1/8npt adapter to screw the sender on. If it's mechanical, assuming it probably has -4an steel braided line on it, you'll need a 1/16npt to -4an adapter.
04-05-2011, 09:32 AM
#5
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Join Date: Dec 2006
Location: Saint Augustine, FL
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The whole schrader valve and stem come out, and the threads into the rail is 1/16th npt.
Is the gauge electric or mechanical? If it's electric, you'll need a 1/16npt to 1/8npt adapter to screw the sender on. If it's mechanical, assuming it probably has -4an steel braided line on it, you'll need a 1/16npt to -4an adapter.
Is the gauge electric or mechanical? If it's electric, you'll need a 1/16npt to 1/8npt adapter to screw the sender on. If it's mechanical, assuming it probably has -4an steel braided line on it, you'll need a 1/16npt to -4an adapter.
If you are permanently installing the sending unit removing the entire valve and using an adapter as suggested by KillJoy is a better route.
Make sure you get a 1/16" NPTF fitting--the F specifies it as being for fuel system use--anything sold for automotive use will be--Autometer has them for pretty cheap. Some of the brass fittings sold in hardware store will not be NPTF.
You can also get an adapter for the Schrader valve here, scroll down about 2/3rds of the page. This adapter makes for easier reversion.
Last edited by cliffyk; 04-05-2011 at 09:38 AM.
04-05-2011, 11:47 AM
#6
5th Gear Member
Thread Starter
Join Date: Mar 2008
Location: PA
Posts: 2,825
Cool thanks guys, I was just gonna take the cap for the valve to the store to find the right size lol. And its an electric gauge...I was gonna start the wiring today but I can't find the motivation...ha
04-05-2011, 12:05 PM
#7
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A comment as to what you will "see":
The pressure at the fuel rail will always be 39-40psi plus the manifold vacuum (plus because vacuum is negative pressure), except certain conditions when it can reach 50+psi as the PCM increases the pressure to prevent vaporization in the fuel lines and rails (it uses IAT and ECT to guesstimate fuel temperature).
So, when manifold vacuum is high (20inHg, or -9.8psi) the rail pressure will be 28-30psi or so and when vacuum is low is will approach 39-40psi.
This can be disconcerting when you first see it...
The pressure at the fuel rail will always be 39-40psi plus the manifold vacuum (plus because vacuum is negative pressure), except certain conditions when it can reach 50+psi as the PCM increases the pressure to prevent vaporization in the fuel lines and rails (it uses IAT and ECT to guesstimate fuel temperature).
So, when manifold vacuum is high (20inHg, or -9.8psi) the rail pressure will be 28-30psi or so and when vacuum is low is will approach 39-40psi.
This can be disconcerting when you first see it...
04-05-2011, 12:38 PM
#8
3rd Gear Member
Join Date: Feb 2008
Location: Delaware
Posts: 801
Another option would be to get the adapter that you put under the fuel pressure regulator. It has a 1/8 npt port on the side that you can thread the electric sendering into. This would allow you to keep the schrader valve for other testing purposes.
04-05-2011, 01:00 PM
#9
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
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There is no FPR on the returnless systems ('99+), just a pressure sensor--the PCM sends a PWM signal to a fuel pump controller, that regulates voltage to the fuel pump to control the pressure.
My '03 doesn't even have a Schrader valve...
My '03 doesn't even have a Schrader valve...
