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Discussion Starter · #1 ·
I decided I wanted a more reliable oil pressure gauge line for my 427 mk4 engine. I wanted to run #3 PFTE line from the 1/2 NPT port above the oil filter. Due to the proximity of headers, I did not want to run a nylon line. I tried the copper line but did not like how it looked.
I wNted to switch to a no worry set up.

I’m using the factory brass 45 degree adapter (1/2 to 3/8 NPT) with an aluminum 3/8 NPT to -3AN. The hose fitting is 90* zinc plated steel. I know, that’s quite a few dis-similar metals.

I could not find a brass 3/8 to -3AN adapter. I need a tight 90* line fitting due to headers and z-bar all in close proximity.

Thoughts on brass & aluminum with a steel line fitting? Good to go or a no go?

Joe
710550
 

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Summit has AN Adapters of just about every size. You put in fitting 1 and fitting 2 in the filters...

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Discussion Starter · #3 ·
Summit has AN Adapters of just about every size. You put in fitting 1 and fitting 2 in the filters...

Sent from my SM-G998U using Tapatalk
Thanks but I found the fittings I need, only they are all different metals. Zero brass NPT to AN, in anything. I need the tight 90 degree in order to keep the line away from the header. The tight 90’s are only in steel. Checked Jegs, Summit, and my Fragola catalog. Not a lot of 3AN in aluminum. Seems to be the line size used for brake lines. Hence steel fittings.
Initially, I had a 1/8 NPT to 3AM steel 90 in the factory brass fitting but I could not line up the steel to point where I needed it. The straight aluminum NPT to 3AN will work better with a 90 line fitting but I’m adding aluminum between brass and steel. Not sure if the dis-similar metals will cause a galvanic reaction.
The fittings in the picture is what I have to work with, the brass 1/2 to 3/8 is still on the block.

Joe
 

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I had this issue in my 68 Camaro big block. I used a 3/8NPT to -3AN and bought a premade Russells -3 braided hose and ran a -3 to -3 bulkhead connector at the firewall, then another -3 hose to an adapter for my console gauge. OEM used a bastard tube fitting at the gauge. You dont need a large line, its only a signal feed line for a gauge.
 

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Discussion Starter · #5 ·
Steve,
Did you mix your metal types in building your system? Most sights claim galvanic reaction mostly occurs in wet atmospheres. Not that my engine will see water but it’s in a tough area to view. Once the z bar is in, the area gets pretty inaccessible. Hence the need for a reliable set up. I do plan to use teflon tape between the brass and aluminum. That would only leave the steel line Fitting in contact with the aluminum.

Joe
 

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Personally I think your putting too much thought into this and doubt you'll ever have an issue. Teflon tape will not prevent contact of the threads to one and other.
 

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I decided I wanted a more reliable oil pressure gauge line for my 427 mk4 engine. I wanted to run #3 PFTE line from the 1/2 NPT port above the oil filter. Due to the proximity of headers, I did not want to run a nylon line. I tried the copper line but did not like how it looked.
I wNted to switch to a no worry set up.

I’m using the factory brass 45 degree adapter (1/2 to 3/8 NPT) with an aluminum 3/8 NPT to -3AN. The hose fitting is 90* zinc plated steel. I know, that’s quite a few dis-similar metals.

I could not find a brass 3/8 to -3AN adapter. I need a tight 90* line fitting due to headers and z-bar all in close proximity.

Thoughts on brass & aluminum with a steel line fitting? Good to go or a no go?

Joe View attachment 710550
Joe, I can't say I've ever used multiple metals in an automotive application before, but in my work place, we do that on a daily basis. I'm an aircraft mechanic, and I install threaded titanium studs, and cad plated steel studs into into magnesium transmission gearbox housings, along with steel lock rings, and chromoly steel jack out pads, and steel dowel pins and steel bearing liners as well as steel bushings into magnesium and aluminum gearbox housings. So we use multiple metals which are in contact with each other.

The only thing we have an ongoing problem with as far as corrosion, is in the counter bores of the threaded holes of the magnesium housings. And that's due to magnesium corroding very easy. Many transmission housings on aircraft have to be made of magnesium due to it's light weight. As you can imagine, the power to weight ratio of anything that flies is of utmost importance. Anyway the point being that among those four metals that I install together, (magnesium, titanium, aluminum, and steel) the only thing that I've ever seen or heard about being corroded was the magnesium itself, and never the other three metals. So since you're not using magnesium in that mix, my guess is that you won't have a problem.
 

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1968 Malibu sport coupe, 489 ci. 590 hp 600 tq, RV T-400 Freakshow 3200 stall, 3.73 12 bolt posi
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I wouldn't use a steel tubing it could crack to easy, also if you make a couple small loops in your oil feed line it will absorb any vibration, most small ac refrigerant lines inside units are designed that way to prevent pre mature leaks, personally I like using copper lines, brass fittings
 

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Discussion Starter · #9 ·
Thanks Bill, I appreciate you posting your experience on my thread!

Shovelrick, I guess I was not clear in my line choice. I’m using braided stainless steel tube with a PFTE liner. It should dowel in the hot environment nestled under my #7 header tube and z-bar.

Joe
 
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1968 Malibu sport coupe, 489 ci. 590 hp 600 tq, RV T-400 Freakshow 3200 stall, 3.73 12 bolt posi
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Oh I misunderstood, maybe use some heat insulation wrap around the header area on the oil line?
 

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I’ve mixed aluminum, steel and brass fittings as needed to make the application work and never had a problem.

I was just thinking recently about going to a braided steel line for my oil pressure gauge, I had to come off the front of my block because the rear one above the filter was pointed directly at the Z bar so I have a long copper line that is much better than the plastic ones, but over time I’m afraid it’ll be susceptible to vibration and crack.

Devin
 

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I haven't decided yet how I'll rig up the oil pressure line. The way I had it before I recently disassembled my engine was with a 3" long aluminum fitting with threaded ends, and a 45 degree aluminum fitting attached to it. But if some of you are using copper tubing, you might want to consider using nickel/copper line like this stuff here below, and as I'm sure that you already know, it can be bent with your bare hands without kinking as long as it's smaller than a 1/2" diameter, (the 1/2" stuff requires a bending tool).But it's supposed to be much stronger and more durable than straight copper tubing is...

Fedhill brake line - Where to buy brake line, fuel line, brake line flaring tools, brake line nuts and brake line fittings (fedhillusa.com)
 

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Discussion Starter · #13 ·
Bill,

I always had the nylon tube oil pressure lines on my small block Chevelles, back in the day. Actually, I believe nylon was used in 1967 on the Chevelle. Prior to that it was steel.
Nylon was out of the question with headers On my 427.

I didn’t want to use steel and I was less than thrilled with copper, vibration/work hardening. I’ve updated and over engineered pretty much everything on this vehicle so far, why leave my oil line old tech? Hence my PFTE lined, stainless steel braided, -3AN, oil pressure line. Overkill? Absolutely, par for the course. 😁

Joe
 

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Bill,

I always had the nylon tube oil pressure lines on my small block Chevelles, back in the day. Actually, I believe nylon was used in 1967 on the Chevelle. Prior to that it was steel.
Nylon was out of the question with headers On my 427.

I didn’t want to use steel and I was less than thrilled with copper, vibration/work hardening. I’ve updated and over engineered pretty much everything on this vehicle so far, why leave my oil line old tech? Hence my PFTE lined, stainless steel braided, -3AN, oil pressure line. Overkill? Absolutely, par for the course. 😁

Joe
Joe, instead of having that oil line running to the gauge, I decided to go more modern by installing an oil pressure gauge that merely has an electrical wire going to it, with a sending unit that installs near the back of the block. Instead of having on oil line that can leak, it has a wire that comes out of the sending unit itself, which goes right to the gauge. And you can get the digital gauges with one of these, or an analogue gauge. Summit racing also has their own brand of these too.....



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Discussion Starter · #15 ·
Wow, pretty cool! If I were ot so far along with this Odessa, that’s a route I’d explore.
Joe
 
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