**Sizing Up the Perfect Copper Fuel Line for Your SBC Tri-Power Setup**
(What Size Copper Pipe For Sbc Tri Power)
Building a classic SBC Tri-Power setup is like cooking a great meal. You need the right ingredients. One key ingredient is the fuel line. Pick the wrong size, and your engine might choke or flood. Let’s talk copper. Why copper? It bends easy, resists corrosion, and looks killer under the hood. But size matters. Too small, and the engine starves. Too big, and fuel sloshes like a lazy river.
First, know your carbs. A Tri-Power setup has three carburetors. Each needs fuel. The middle carb usually handles idle and part-throttle. The outer two kick in when you stomp the gas. This dance requires steady fuel flow. Most builders stick with 3/8-inch copper tubing for the main line. Why? It moves enough fuel for most street setups. It’s common, cheap, and works with stock pumps.
But wait. Some folks swear by 5/16-inch lines. They say smaller lines keep pressure higher, reducing vapor lock. True? Maybe. If you’re running a stock mechanical pump, 5/16-inch might help in hot weather. But if you’ve got a bigger cam or high-revving engine, 3/8-inch is safer. It feeds hungry carbs without strain.
Let’s get practical. Start at the fuel pump. Run the main line up the frame rail. Use soft copper tubing—it’s easier to shape. Avoid kinks. A kinked line is like a blocked artery. Keep bends smooth. A tubing bender helps. No fancy tools? Wrap the tube around a soda can. It’s old-school, but it works.
Split the line near the carbs. Use a “T” fitting. Send one branch to the middle carb. Run lines to the outer carbs from there. Keep lengths equal. Balance is everything. Uneven lines mean uneven fueling. One carb might hog gas, leaving the others dry.
What about fittings? Brass is best. It seals tight and won’t corrode. Use flare fittings, not compression. Compression fittings can leak under vibration. Flare them properly. A bad flare is a fire hazard. Don’t skip this.
Pressure matters. Stock mechanical pumps push 4-6 psi. That’s plenty for copper lines. If you’re using an electric pump, add a regulator. Too much pressure bends copper over time. Check for leaks. Fuel smells nice, but you don’t want it pooling under the car.
Some guys braze copper lines. Don’t. Solder melts under heat. Use flare fittings instead. Safe and simple. If you must solder, use high-temp silver solder. Still risky, though.
What if you’re racing? Go bigger. A 1/2-inch line might help. But for street builds, 3/8-inch is the sweet spot. It’s proven. Thousands of Tri-Power Chevys run it daily.
Still unsure? Test it. Hook up a pressure gauge. Watch how the needle behaves when you rev the engine. If it drops, the line’s too small. If it stays steady, you’re golden.
Copper’s not forever. Check it yearly. Look for cracks or green corrosion. Replace it if it’s crusty. Fuel systems hate surprises.
(What Size Copper Pipe For Sbc Tri Power)
Final tip: polish the copper. A shiny fuel line adds bling to your engine bay. It’s not just function—it’s style. After all, a Tri-Power SBC is a showstopper. Make the fuel line part of the show.
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