GRT Manifold Pressure Sensor

I'm trying to install a GRT Manifold Pressure Sensor and the instructions show a: vacuum line (7/64"-3/16" ID vacuum line, such as Lifeline Part #301201).

I can't seem to find one. Lifeline is a medical supply house, but no such part. The kit includes a tiny short length of 7/64". The box will go inside the panel, so the transition to 3/16" could probably happen anywhere. The firewall, perhaps? What have others done? Thanks,
John

johngoodman said:

I'm trying to install a GRT Manifold Pressure Sensor and the instructions show a: vacuum line (7/64"-3/16" ID vacuum line, such as Lifeline Part #301201).

I can't seem to find one. Lifeline is a medical supply house, but no such part. The kit includes a tiny short length of 7/64". The box will go inside the panel, so the transition to 3/16" could probably happen anywhere. The firewall, perhaps? What have others done? Thanks,
John

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I used a kit from Vans that included a bulkhead fitting, hose and a fitting that screwed into a port on #3 cylinder. The GRT tubing easily reached from under the panel of my -8 through the baggage compartment to the bulkhead fitting.

I think my manifold sensor from GRT had a couple of feet of tubing with it. How much came with yours?

Don't laugh, but...

I used the black noepreme tubing that comes with the "Mister" irrigation kits that you can buy in the plumbing section on the aircraft aisle at Lowe's. It's pretty stout stuff and after 800 hours it shows no sign of deterioration in the hot cowling environment. And it is dirt cheap!

I think my manifold sensor from GRT had a couple of feet of tubing with it. How much came with yours?

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Mine came with just 12 inches of 7/64" tubing. Sounds like GRT is scrimping a little. With all the GRT EISs out there, I would think that there is a simple transition of some type around. I can't even find adapters in the 7/64" range at McMaster-Carr. My problem is not where to find tubing, it's the transition to a larger size - preferably at the firewall.

John

I ran 1/8" stainless steel tubing from a point near the GRT sensor behind my panel to a convenient point on the motor mount near the manifold pressure tap on the engine. I then ran another short piece of SS tubing with a compression fitting from the engine tap to a point about 6" from the first (longer) piece of SS tubing. I used the short piece of plastic from GRT (only about 1FT for a service loop) to connect the sensor to the first SS line behind the panel. For the FWF plastic line, I bought some small fuel line tubing at a hardware store. Get the kind you'd use for a weedwacker or similar small engine powered yard tool or chainsaw. Just used safety wire wrapped a couple times to clamp the small fuel line hose to the SS tubing. Works great so far...

also have questions

It is interesting how many "timely" threads I have been running into lately. I am also working on trying to connect the GRT Manifold Pressure box but I have an additional problem. I have a Lightspeed Plasma III EI that needs the manifold pressure fed to it also.

My problem is the bulkhead fitting I have coming through the firewall is 1/4 inch while the GRT box and the Plasma III box are smaller (I assume 7/16 as others have posted). So I need to split off of the bulkhead fitting and go to two different locations with the smaller fitting size.

Here is a picture of my sub panel. My GRT manifold pressure box is mounted at the top of the picture (black box with white label). Directly in front of it on the firewall is a bulkhead fitting coming from the engine. That bulkhead fitting is 1/4 in. that has to reduce down to whatever size the GRT box has. As mentioned, I also have to route another line off of that same bulkhead fitting over to the Plasma III. It is barely visible at the bottom of the picture mounted to the backside of the sub panel.



Does anyone have ideas on how I can split off of the bulkhead fitting to the smaller fittings on the two instrument boxes?

Steve - check out Jerry Thorne's website

If I remember correctly I think Jerry had to branch off his line for an electric ignition. I don't remember exactly which pages show it but check his website - http://www.n2prise.org.

Fearless said:

If I remember correctly I think Jerry had to branch off his line for an electric ignition. I don't remember exactly which pages show it but check his website - http://www.n2prise.org.

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Thanks Feerless. The best I can tell he has a picture on page 84 of his firewall forward, wiring and finishing section. However, there is not enough detail to see exactly how he spit things off.

Jerry, if you read this thread could you contact me to discuss how you ran your MP lines? I also would welcome any other comments from others.