Does size matter?

notjustair · Dec 13, 2016

On an oil sending unit supply line, at least? Here's a picture of the back of the dash on my 35 Chevy. The fuel gauge is the one with the scary wiring (which worked until I saw those wires and cut the supply line!). Under that is the oil pressure line. It appears to be 1/8 inch copper or something. It's way smaller than it appears in that photo. I've been really lucky up until this point but it will leak eventually. If the replacement isn't the exact inside diameter will it affect the gauge reading? I'm thinking with a garden hose you have the same pressure regardless of the hose diameter, but we are talking a really old oiling system that isn't truly pressurized. It has a vane oil pump and rod cap cups to help boost pressure. It runs around 15 pounds but that's clearly a miracle if you've seen the Rube Goldberg contraption producing the oil "pressure".

Greg1959 · Dec 13, 2016

A pound is a pound. LOL

Bob · Dec 13, 2016

I think original line would have been 1/8" steel.

Should be still available, some of the gauge installation kits included copper line, though.

The internal compression nuts are still readily available as well, (if an when it does need replacing) there's no need to change to anything of a different size/different fittings. They are sometimes called "Double Compression (Threaded Sleeve) Fittings".

<img src = "http://cdn3.volusion.com/9wsnr.t9nao/v/vspfiles/photos/A192-1.jpg?1466158023">

On another note, we apparently never did convince you the dippers on the rods simply scoop up oil for the individual rods and DO NOT boost pump pressure???

notjustair · Dec 13, 2016

Gong! Check out the oil pan. The dippers force the oil into tubes at each rod pan. The tubes are all tied together through a fantastic spaghetti of tubing. After they all join together they go up the left side of the oil pan where that line meets up with the oil pump line and runs together to the external oil pressure regulator. At that regulator the line runs to the gauge and also passes back through the block to go up to the head to oil the valve train.

NCWayne · Dec 13, 2016

As Greg says, a pound is a pound. As such, you'll get the same reading on the guage, regardless of the size of any of the components in the system.

leroy in ne · Dec 13, 2016

have 1940 shop manual for chev. actually there was a fixture made to align the oil tubes, water was injected into the oil gallery and the tubes were bent so the stream of water went thru a hole in the fixture. in use the dipper troughs were filled by the tubes at idle and slow speed as engine speed came up windage from the crankshaft blew the oil out of the troughs and the oil tubes actually shot oil into the dippers to lubricate the rod bushings. I know more usless info but what the heck maybe some one will remember and do more research.

Steve@Advance · Dec 14, 2016

This kind of stuff makes you scratch your head wondering "What were they thinking?"!

TomA in CA · Dec 14, 2016

I don't think there were too many bearing failures on those old Chevies, they mostly died burning oil.

Richard G. · Dec 14, 2016

Old mechanic in town used one of those fixtures when I rebuilt my 51 Chevy 3100.
Richard

Richard G. · Dec 14, 2016

Steve, that old squirt oiling system worked very well for the speeds of the day. My 51 Chevy 3100 is still running.
My 17 Model T just dips in a little oil as the connecting rod goes around. I like to tell folks it is the splash and hope oiling system.
Richard

Texasmark1 · Dec 15, 2016

Agree since flow sets pressure drop and hence gauge potential errors and with a gauge, once activated has no flow.

Does size matter?

notjustair

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Greg1959

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Bob

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notjustair

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NCWayne

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leroy in ne

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Steve@Advance

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TomA in CA

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Richard G.

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Richard G.

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