Oil Lines - 1/4"; 5/16"; or 3/8"??

[Chobber69]

Gettin wrapped up in something probably dirt simple. So I measue the O.D of the barbs on the oil pump & see it's a cool 3/8" OD. No problem so far. Now... the trick is to just buy 3/8" ID hose, right? Maybe. The size of these hoses, when you measure the OD is huge....like 5/8"!! Is it possible to go with something more streamlined, like say: 5/16" I.D. X 9/16" O.D...without restricting oil flow? If you think about it; 5/16" is kinda "in-between"...a compromise for my sensitive nature? Any thoughts? -Dennis Lee Hopper: R.I.P.-

[Frankenstein]

Stick with 3/8" for any runs where it's important for the oil to get there.
I don't know of any definitive studies of 60 weight flow vs line diameter, but a fellow on the flathead power webboard discovered issues with cavitation at the oil pump with cold oil and circuitous oil passages, so I'd play it safe.
DD

[hjans]

Inner diameter should fit thight on the barbs
outer diameter is less imnportant, but be aware thet a "thin"hose kinks very easyli.
Why not use steel ? Change the barbs, use steel/aluminium, looks good and thin lines !
Hans

[Chobber69]

Appreciate the pointers, on this one. Measured the inside/outside diameter of the hard lines, I got a while ago: 1/4" I.D x 3/8" O.D. Guess I was looking to be lazy & not swap out the slip-on barbs at the pump (Sifton), w/threaded type...as per the hard lines. In my defense, the default building my bike to date has been - nothing fits i.e. stock anything used with aftermarket setups....reqr unique mating rituals. Even though the old horseshoe is in a paughco (wishbone) frame, w/stock dimensions is a pain! Hard lines it is...thanks for keeping me "on track". My project is somewhere on the gallery, call it Pan-Clone!

***Anyone know the thread size? 1/8NPT or close?

[biker_k]

Thinner I.D. lines will increase your oil pressure and/or decrease the flow. I wouldn't mess around with the design of the system. Stick with 3/8" where it is installed. Let's just use an example. The return oil line is 3/8". If you change it out with 5/16", then you are increasing the pressure in the return and decreasing the flow. I don't think that's a good thing. I would assume the more flow in the return the better. Of course, these are just my thoughts. Maybe someone else will pipe in here and tell me I'm wrong. I've been wrong plenty of times.

[Chobber69]

biker_k: When I measured the I.D. on the hard lines, the measurment was a cool 1/4", w/3/8" O.D. The O.D. doesn't matter agreed, but figure the restriction of the oil flow has already been set at 1/4" I.D. from the barb; either at the pump or oil bag? Other than perhaps "kinking" a line, using smaller diameter hose; the formula appears to be 1/4" I.D. I've noted that custom shops & chops sometimes employ copper lines, which look like an onboard distillery...dependant on the creativity of it's owner! The hard lines, which are stock 1/4" I.D. appears to have survived the years as being workable; just have to figure out which one I am going to stick with now (lines or hoses)...

[biker_k]

as long as the I.D. is the same, you should be good.