question on lines for oil pressure gauge

[RacerBill]

I received a nice set of AutoMeter gauges and have a question about the line for the mechanical oil pressure gauge. I remember reading somewhere on this forum not to use the plastic tube that comes with the gauge. But when I went to Jegs to get the AutoMeter braided line, the sales person advised against it, saying that it would cause the meter to read low by about 10 pounds (because of the diameter of the line). He recommended the brass tubing.
Comments and/or advice?

Thanks.

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Bill Stevens
Mbr 103106
BnS Racing
83 ITA Shelby Dodge Charger

[Joe Harlan]

Do not use brass or copper. -3 is about the same diameter as the stock tube that is supplied. I use -4 to because the gauge reacts much quicker. There is no way that larger line can reduce the pressure reading. Pressure is pressure once the line is charged. Larger line allows for a quicker reaction by the gauge which will allow you to catch pressure drop quicker.

[joeg]

Autometer itself sells a braided line alternative to the NYLON line that comes with the gauge. They give no warning about "lower" readings with that braided line, so what you were told is probably an old wive's tale.

I have used the braided lines for ages and the reason you use them is that they are tough and can take a lot of abuse with motor changes and the like.

That being said, there is absolutely nothing wrong with the Nylon line and they are actually used in aircraft. As long as they are secured properly and not subject to abuse, they will work just fine.

Good Luck.

[C. Ludwig]

I use the Autometer braided line with my gauges and the oil pressure is right where it should be for this type of motor versus others I've built that have used a copper line. Wow...that's a run-on sentence if I ever saw one. http://ITForum.ImprovedTouring.com/smile.gif

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Chris Ludwig
08 ITS RX7 CenDiv

[x-ring]

I guessing that sales person failed high school physics.


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Ty Till
#16 ITS
Rocky Mountain Division

[Knestis]

I was thinking the same thing...

I would use plastic for oil pressure without worrying but that's just me. I used barbed fittings and good quality rubber lines for oil coolers for years, too without any problems.

K

[JeffYoung]

Don't oil lines that go into the cockpit have to be steel braided, including the one carrying oil to the pressure gauge?

[MadFrog]

Originally posted by JeffYoung:
Don't oil lines that go into the cockpit have to be steel braided, including the one carrying oil to the pressure gauge?


yes. at least, that's my understanding of the rules.

[x-ring]

Originally posted by JeffYoung:
Don't oil lines that go into the cockpit have to be steel braided, including the one carrying oil to the pressure gauge?

Steel or steel braided. Brass or copper isn't allowed, come to think of it. I don't remember the rule number off the top of my head, but I think it's in the 17.30's.

EDIT: I'm not a rules nerd, yet, but I did work tech last weekend.

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Ty Till
#16 ITS
Rocky Mountain Division

[This message has been edited by x-ring (edited March 29, 2005).]

[RacerBill]

Makes perfect sense to me. Thanks for the advice.


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Bill Stevens
Mbr 103106
BnS Racing
83 ITA Shelby Dodge Charger

[JohnRW]

The cheapest places to purchase pre-assembled -3 and -4 braided hoses are the roundy-round supply houses like Lefthander and Coleman Machine, or the retailers like JEGS or Summit Racing. You can't buy the parts to build a briaded line as cheaply as they'll sell you a completed assembly for...along with any NPT or -# adapters.

(anticipating the question here)

[Dick Elliott]

AFCO Racing has the an lines up to 48" long and cheep.