GoToGuy is correct. You can go flare to metric/o-ring or...
You can go with the same flare, (filing the sharp outer edges of the flare), slip on a hose and carefully crimp a rubber line, similarly as a factory crimp using the following tools and crimpers.
Barb fittings, with brass compression fittings work well too.
You must be registered for see images attach
You must be registered for see images attach
https://www.hotrod.com/articles/hrdp-1101-performance-fuel-hoses/
You must be registered for see images attach
Buy one of these tools, with a go-No Go Gage:
xc_hide_links_from_guests_guests_error_hide_media
You must be registered for see images attach
Stay away from the giant tweezers style bull nose crimpers, though... they are not nearly as good.
The pictured crimper above, crushes the crimp in 2 directions, making a very strong crimp button.
The bull nose crush the crimp in one direction only. The extra fold is much stronger, especially on the imported non-pex crimps in the next picture.
The real deal stainless 1/2" and 3/4" from Shark-Bite or Pex, is much thicker stainless steel. See the picture below).
Then buy some of these, they are good enough for medium 45-65 psi lines.
I would double them for 50-85 psi. Make certain your crimps are snug and use the correct rubber compounds for fuel, or coolant or P/S lines.
The rubber compound is all very different for each automotive purpose, so do some rubber research before you grab just any hose... HP Fuel line like Gates, Barricade, is in a class of it's own. Coolant hose is not oil line and oil hose is not fuel line...:
You must be registered for see images attach
xc_hide_links_from_guests_guests_error_hide_media
Here's a better picture of a heavy duty 1/2" Shark-Bite.
Notice these have a ring under the crimp section, so the entire fuel or oil line gets sealed?
Some older versions of this crimp rings, do NOT have the full circle and should NOT be used for fuel lines, over 7psi.
They can and will eventually leak and cause a fire, under pressure. Same reason screw style coolant clamps will fail, under the screw machine portion, under pressure. Without the full circle, it makes a bulge and an area which is not really crimped.:
You must be registered for see images attach
The Go-No Go Gauge is designed for establishing exact crimps using pex or Shark-Bite crimps, by tuning the crimper tool to factory specifications. Every so often, if using for real plumbing installs, you verify the gauge is still accurate, or your house plumbing will leak.
When you use these as standard plumbing Pex quality crimps, you compress the tool, full crimp, every time.
The metric assortment I listed above, does NOT come in standard crimp sizes... The assortment pack, should NOT be used with metric crimps on household plumbing... Metric hose crimps are not gauged to the exact outer diameter of whatever SAE rubber hose, you are using on your truck. They most certainly are not sized for pex, unless they are sold by Pex or Shark-Bite Brands.
Think 3/8", 1/2", 3/4"... etc. Heavy duty, use this tool under the sink...
The metric sizes in the assortment are not standard-ized to your new automotive use for this tool.
You'll have to take it easy on the crimping and get them tight, but not all the way home, with the crimper handles. There's a latch to release the handle's, when you partial crimp, to open them back up. They are lighter gauge metal, not rated for commercial or residential home plumbing. They work great for hot-rod repairs on broken hard lines.
You can easily over crimp and ruin the rubber lines, if you are not paying attention, even with the cheaper quality metric assortment crimps.
When you double or triple the metric style crimps (and offset the crimp button), you can secure very high pressure fuel and hydraulics lines, safely. After you buy a few assortment packs and see the difference in quality, between the brands, you can seek out the better versions from the junk.
Standard Stainless coolant screw clamps will NOT work to secure your 60-80 psi oil cooler lines, without very high chance of failure. The metric o-ring fitting in the previous gentleman's post, withstand an enormous amount of pressure.
Using coolant screw clamps on your fuel lines is dangerous and wrong.
Squirting fuel at high pressure all over your hot manifolds... bad day at the track.
The good news is, when you buy this tool and accidentally Sawzall the plumbing in your wall, later on in life, you'll have the tool to repair your plumbing, with plastic pex and it will use the full crimp process to keep from flooding your home.
I have seen pex used on automotive lines and it seems to work well, when thought out and for certain applications.
There's guy running rigid clear acrylic tubing on his hot-rod with green glycol and a lot of chrome, and it looks really cool flowing with the engine running coolant through clear lines on his show truck.
You must be registered for see images attach
Plumbing your Chevy, without spending a fortune for custom crimped lines can be done with a bit of practice and a few good tools.
New O-Rings on every line, every 5 years, is probably a good idea, if you want to get the most from your truck.
In severe heat climates, down South, the hoses are probably rotten after six years.
The O-Rings will be square. You might think they are flat washers, if you hadn't seen a thread like this one.
The check balls in the oil filter mount, which feed the lines in your picture are probably ready to be replaced, if your oil cooler lines are shot. However changing these clogged arteries, is for another thread...
xc_hide_links_from_guests_guests_error_hide_media
You must be registered for see images attach
Replacing and repairing hard lines on the GMT400 can be very difficult.
Mistaking NPT for NPS threads can ruin your truck's oil, cooling, hydro-boost system and transmission.
You must be registered for see images attach
There's a bunch of threads by guys who swapped out the 4L80E o-ring clip fittings and bought aluminum flare fittings and the manufacturer sold them a raft of crap. Ruined the transmission because of leaks.
Instead of two of the right side of the diagram fittings, which are supposed to have o-rings, they sell two fittings just like the picture above.
One of each. The left one leaks, ruins the transmission. The picture is not the best example, because the actual thread pitch on some of these fittings is exactly the same and they will thread into eachother seemingly well.
Until they break or loosen up and drain all your fluid on a three hour drive.
Sometimes, you have to know when to switch over with a good crimper and ditch the worn out hard lines altogether.
Here's one option:
Leave the push fit o-ring compression metric end or the push metal spring clip style ends,
Saw off the damaged or offending hard line,
flare to stop the crimp from slipping off the tubing,
File the sharp edges of your flared tubing with a small file, (The sharp flare will rip the inner lining of your expensive Barricade High Pressure Fuel line)... You can round the flare so it looks like a ball, if you want.
Crimp a quality pair of ring crimps...
This process can save your sanity and get you up and running, without spending a fortune for custom or out of stock factory style lines.
Never use these on brake lines.
Change your Gates Barricade High Pressure Fuel Lines and re-crimp with fresh fuel line o-rings, every 5-6 years.
Just to be on the safe side.
I hope this long post helps.
