A loyal follower of my build thread has informed me that he had trouble with his aluminum fuel line that went between "the car" and "the engine" - even though he has solid motor mounts. I also have solid motor mounts and a mid-plate too. Do you see a problem with my set-up? I know the AN fittings are not HAMB friendly. He had trouble with the flare cracking over time, not much time by the way. I'm wondering has anybody had the same trouble or has anyone run like this with no trouble at all? Thanks!
Aluminum is fine in drag racing applications but all manufacturers eliminated the use of aluminum for fuel line back in the 60's due to fatigue and leaks. Also, no one I know of would even think of using hard-line right up to the carbs. Your work and your car look great but I think you're asking (begging) for problems. Go with some kind of flex line to the carbs.
plumbid>>>Do you see a problem with my set-up?>>> Not yet. I prolly would've looped the lines a few times to allow for a lot more flexing than you're gonna get with that setup. Jack E/NJ
You can't totally isolate them from vibration regardless of how the engine is mounted. Sooner of late fatigue will cause a problem and with fuel lines it could be a big problem.
I'd run some braided or rubber line from the fuel block too the carbs... Even though your using solid mounts, your still gonna get some engine twist when you put your foot in it... I twisted the shit out of a couple pair of lakewood solid motor mounts with my 302 Z/28 I once owned...
I thought of that too, and tried a sample chunk - the radius was so big, it would have looked like a plate of spaghetti!
Anyone who thinks AN fittings don't belong on the HAMB don't know what they are talking about. They have been around since WWII and were picked up by Hot Rodders after the war as surplus. Let me guess - the same people running solid aluminum fuel lines to a vibrating engine probably think fire extinguishers aren't HAMB friendly either?
I remember when the Indy racers first used AN lines for external oil coolers and they started breaking after 300 miles in the 500. Vibration is the problem and aluminum fatigues.
Never done it but if I did I would coil it like a spring a few times to give it some extra flex and movement
My regulator is bolted off the front of my head, aluminum line run up to it off the frame. I have a rubber insulated mount on the crossmember that the line runs through, after that it's not touching anything until it gets to the regulator. The line has a nice big radius going up from the frame area, so there is plenty of room around the line just incase my solid mounts or frame flex. Off the regulator I have braided line to the carbs, in the rear from pump to line I do have a piece of rubber line between the two.
Rigid/solid lines are asking for a leak (at the low end of the trouble spectrum) up to a catastrophic failure/fire. I used "push lock" style AN fittings and the corresponding style hose for mine. All the marketers of AN stuff now make it available. If you are not a fan of the red/blue stuff (like me) black is a good alternative. Best of all, NHRA accepts it, unlike the limitation they place on rubber/hose clamped, nipple type connections. Contact me off here with a PM, might have enough leftovers from mine to help you.......
About the braided lines: They are rubber inside but you might want to remove and blow them out occasionally. We are sometimes seeing tinny rubber debris inside them in aircraft applications. It may be due to the added weight of the braided outer sheath flexing the current crap they call rubber. Even Goodyear aircraft tires and tubes are splitting now. I went back to plain old rubber so I can check for cracking from the outside.
Rigid tubing is fine if supported correctly but you will still need a small flexy to avoid vibes, I like PTFE/Teflon braided rather than rubber
I'de can your existing lines. Even with your solid mounting. Get some nylon braided hose(it's black). They even make black fittings......You could run from carb to carb in aluminum,but to your regulator,......probably have some aspirin handy- headache will be comin"
Apparently there are lots of opinions here. I doubt anyone cares, but here's mine. After 7 years at a speed shop and after 14 years as an engineer, your setup will fail. You need a flexible component between the firewall and carbs. You stand a better chance as the line gets closer to the mount. i.e. it "might" be ok for a while if you were to run along the frame and followed the motor mounts to the engine... but i still wouldnt recommend it. I would (and have, many times over) recommend aluminum fuel line for a 90% + drag car ONLY. Aluminum does not hold up as well as steel, period. Mine is stainless. I prefer rubber hose or the rubber core SS braid, it doesn't kink as easy as the teflon, and is plenty of pressure for any fuel system. NHRA or not, 10' of rubber properly supported is better than all solid aluminum line. Unless, of course, youre competing in an NHRA sponsored event.
We were using 6061 t-6 sheet in beverage truck fabrication and found a great deal of stress cracking and work hardening after several months use. Our engineer had us change to a softer grade and solved the problem. That is one reason not to use aluminum on fuel lines, softer grades of stainless should be ok.
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