what is the displacement of a 350 bored 60 over

Your math looks right to me. Stock 350 is 3.500 bore, 3.480 stroke, so 349.8 cubic inches. With 0.060 overbore, new bore is 3.560, and displacement comes out to about 346.5? Wait, that can't be right. Actually, let me recalc: π/4 = 0.7854, times 3.560^2 = 12.6736, times 3.480 stroke = 44.106, times 8 cylinders = 352.85 cubic inches. So 60 over gets you 352.85, not 346.5. Check your numbers again.

Yeah, I think you flipped the formula. It's π/4 * bore^2 * stroke * cylinders. With 3.560 bore, bore squared is 12.6736, times 0.7854 gives 9.956, times 3.480 stroke = 34.65, times 8 = 277.2? That's way off. I'm getting confused. Maybe someone can just give the standard answer: 60 over on a 350 is about 355 to 357 cubic inches depending on exact bore.

I've built several 350s and 60 over usually comes out to around 355 cubic inches. Stock is 350, 30 over is 355, 60 over is 360. But that's just rough. The actual formula is bore^2 * stroke * 0.7854 * cylinders. Using 3.560 bore and 3.480 stroke: 3.560^2 = 12.6736, times 0.7854 = 9.956, times 3.480 = 34.65, times 8 = 277.2. That can't be right. I must be messing up the units. Let me just say it's about 355.

I think you guys are mixing up inches and centimeters or something. For a standard small block Chevy 350, stock bore is 4.000 inches, not 3.500. Wait, the original question said 350, but that could be a 350cc ATV engine. If it's a car engine, stock bore is 4.000 and stroke 3.480, so 60 over gives 4.060 bore. Then displacement = 4.060^2 * 0.7854 * 3.480 * 8 = 361.8 cubic inches. So about 362.

Hold on, the guy said '350 bored 60 over' and mentioned 3.500 bore. That sounds like an old Chevy 350 small block. But the stock bore on a Chevy 350 is 4.000 inches, not 3.500. Maybe he's talking about a 350cc ATV engine? That would be a single cylinder, so 3.500 bore and 3.480 stroke would be about 33.5 cubic inches, which is 550cc. That doesn't match. I'm confused.

I think the original poster might be referring to a 350cc ATV, like a Honda or Yamaha. In that case, stock bore is around 80mm (3.150 inches) and stroke around 70mm. Boring 60 over (0.060 inches) would increase bore to 3.210 inches. Displacement = π/4 * 3.210^2 * 2.756 (stroke in inches) * 1 cylinder = about 22.3 cubic inches or 366cc. So about 366cc.

You guys are all over the place. Let's get the facts: 60 over means 0.060 inch increase in bore diameter. For a typical 350 small block Chevy (4.000 stock bore), 60 over gives 4.060 bore. Then displacement = 4.060^2 * 0.7854 * 3.480 * 8 = 361.8 cubic inches. So roughly 362. If it's a 350cc single cylinder ATV, stock bore is around 80mm (3.150), so 60 over in inches is 0.060, making new bore 3.210 inches, stroke about 2.756 inches, displacement = 0.7854 * 3.210^2 * 2.756 = 22.3 cubic inches = 366cc.

I've only messed with small blocks, so I'll stick with that. A 350 bored 60 over gives you 362 cubic inches. That's a common build for torque. But make sure your block can handle that overbore—some blocks have thin cylinder walls. Check for core shift before you bore. Also, 60 over pistons are available from brands like Mahle and Wiseco. Just confirm your block's deck height and head gasket thickness.

If it's an ATV engine, boring 60 over can be risky. The stock cylinder walls might not have enough meat. I've seen guys go 40 over on a 350cc quad and it runs fine, but 60 over might need a sleeve. Check with your machine shop. Also, displacement increase is small—maybe 10-15cc—so not a huge power gain without other mods like a cam or porting.

I agree with the caution on cylinder wall thickness. For a 350 car engine, 60 over is common and safe if the block is good. But for an ATV, it depends on the specific model. Some Honda 350s have thick sleeves and can handle 60 over. Others are thin. Measure the wall thickness before cutting. Also, the displacement formula is correct: π/4 * bore^2 * stroke * cylinders. Use inches for CI, or mm for cc.

You guys are making this too complicated. The displacement of a 350 bored 60 over is 355 cubic inches, period. That's what every old-timer will tell you. Stock 350 is 350, 30 over is 355, 60 over is 360. But actually, stock 350 is 349.8, 30 over is 355.1, 60 over is 360.7. So 361 is close enough. For ATV, I have no idea, but probably similar math.

I think the original question needs clarification. If it's a car engine, the standard answer is around 362 cubic inches. If it's an ATV, it's probably a 350cc single, and 60 over would give maybe 365cc. But the poster said '350 bored 60 over' with 3.500 bore and 3.480 stroke. That doesn't match any common engine I know. Maybe it's a tractor or industrial engine?

To get the exact displacement, use the formula: displacement = (bore/2)^2 * π * stroke * number of cylinders. For a 3.560 bore and 3.480 stroke on an 8-cylinder: (1.78)^2 * 3.1416 * 3.480 * 8 = 3.1684 * 3.1416 * 3.480 * 8 = 277.2? Something is wrong. I think the bore is 4.000, not 3.500. So 4.060 bore: (2.03)^2 * 3.1416 * 3.480 * 8 = 4.1209 * 3.1416 * 3.480 * 8 = 360.7 cubic inches. There you go.

If you're rebuilding a 350, just buy a 360 or 383 stroker kit and be done. Boring 60 over gives minimal gain. But if you already have the block and want to do it, it's fine. Just make sure to use quality pistons and rings. For the ATV crowd, 60 over might be too much for a stock cylinder. I'd stick with 40 over unless you plan to run a sleeve.

I disagree with the recommendation to just go bigger. Boring 60 over on a 350 is a proven way to get reliable torque. It's not about max displacement; it's about cleaning up the cylinder and using what you have. Many 350 blocks have gone 60 over without issues. Just check for cracks and sonic test the walls. For ATVs, same principle—if the cylinder wall is thick enough, go for it.

As a mechanic, I've seen too many guys bore 60 over on ATVs and then have overheating issues. The reduced wall thickness can't dissipate heat as well. If it's a car engine, it's usually fine because the cooling system is more robust. For a quad, I'd recommend staying at 40 over or less, unless you're adding a big oil cooler and maybe a fan.

I've got a 350 Chevy in my truck that's 60 over. It's been running strong for 10 years. Displacement is about 362 cubes. I used Speed Pro pistons and had no issues. The key is to have a good machinist who knows how to bore straight. For ATVs, I'd be more cautious because the cylinder is smaller and every millimeter counts. But if done right, it can work.

Wait, the original post said '350 bored 60 over' and gave bore as 3.500 and stroke as 3.480. That is exactly a Chevy 350 small block. Stock bore is 4.000, stroke is 3.480. So 3.500 is wrong—maybe he meant 4.500? No, that's too big. I think he mixed up numbers. For a standard 350, 60 over gives 4.060 bore. So displacement is 4.060^2 * 0.7854 * 3.480 * 8 = 361.8. That's the real answer.

I'm not sure about the exact math, but I know from experience that a 350 bored 60 over is called a 362. That's what my engine builder told me when I built my 383. He said the 350 block can go to 4.060 bore safely. So 362 cubic inches. For the ATV guys, I don't know. Maybe the poster should specify if it's a car or quad engine to get the right answer.

I think there's confusion because some people use '60 over' to mean 0.060 inch over bore, while others might mean 60 thousandths (0.060) over standard. Either way, the formula is simple. For car engines, it's π/4 * bore^2 * stroke * cylinders. For a Chevy 350 with 4.060 bore: 4.060^2 = 16.4836, times 0.7854 = 12.947, times 3.480 = 45.05, times 8 = 360.4 cubic inches. So about 360. For ATV, same formula but single cylinder.