{"product_id":"castair-3-5-hp-single-stage-i2-cylinder-air-compressor-bare-pump-with-12-flywheel-od-16-oz-oil-capacity-s755","title":"Castair, 3.5 HP Single Stage, I2 Cylinder Air Compressor Bare Pump, with 12 Flywheel OD, 16 oz. Oil Capacity S755","description":"\u003ch2\u003eCastair S755 — 3.5 HP Single-Stage Air Compressor Bare Pump\u003c\/h2\u003e\n\n\u003cp\u003eThe Castair S755 is a 3.5 horsepower, single-stage, two-cylinder bare compressor pump built for shops and contractors who need a reliable cast iron pump head — either as a replacement for a worn pump or as the core of a custom compressor build. With a 12-inch flywheel OD and 16 oz. oil capacity, this is a splash-lubricated, oil-lubricated cast iron pump sized for continuous service in auto shops, body shops, small fabrication operations, and general commercial environments.\u003c\/p\u003e\n\n\u003cp\u003eA bare pump is exactly what it says: the pump assembly only — no motor, no tank, no pressure switch, no controls. You bolt it to your existing tank and motor setup. That is the practical reason shops buy bare pumps — when the pump fails but the motor and tank are still serviceable, you replace the pump head and extend the life of your compressor infrastructure without buying a complete unit.\u003c\/p\u003e\n\n\u003ch3\u003ePump Construction — What Makes Cast Air Different\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAll Cast Iron:\u003c\/strong\u003e Cylinders, crankcase, heads, and valve plates are cast iron — not aluminum. Cast iron dissipates heat better, handles thermal cycling, and holds up to the continuous compression cycles a shop compressor runs every day\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOil-Lubricated Splash System:\u003c\/strong\u003e The 16 oz. crankcase oil lubricates cylinder walls, rings, and rod bearings on every stroke. Oil-lubricated pumps last significantly longer and run cooler than oil-less designs\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eI2 Cylinder Design:\u003c\/strong\u003e Inline twin cylinders deliver balanced compression with less vibration than a single-cylinder pump at equivalent HP\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDisc and Spring Valves:\u003c\/strong\u003e More durable and easier to service than reed valves. When you eventually service the valves, they come apart cleanly and install correctly\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4-Ring Pistons:\u003c\/strong\u003e Four rings per piston means better sealing, less oil carry-over into the air stream, and longer intervals between ring replacement\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e12-Inch Flywheel OD:\u003c\/strong\u003e Factory spec for standard belt-drive sizing in the 3–4 HP range. Sized for correct belt selection when paired with a 1725 RPM motor using standard sheave ratios\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSKU:\u003c\/strong\u003e S755\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHorsepower:\u003c\/strong\u003e 3.5 HP\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePump Type:\u003c\/strong\u003e Single-stage, reciprocating piston\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCylinder Configuration:\u003c\/strong\u003e I2 (inline 2-cylinder)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlywheel OD:\u003c\/strong\u003e 12 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOil Capacity:\u003c\/strong\u003e 16 oz.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLubrication:\u003c\/strong\u003e Oil (splash lubricated)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eComponent Type:\u003c\/strong\u003e Bare pump — no motor, tank, or controls included\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair), family-owned since 1991\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $445.06\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eNote: CFM output and max PSI ratings are dependent on RPM and pulley configuration. Contact us at 866-217-0063 with your motor HP, motor RPM, and intended tank size for correct sizing guidance before ordering.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eCast Air S755 bare pump assembly\u003c\/li\u003e\n  \u003cli\u003eNo motor, tank, belt, or controls — these are sourced separately or existing components are reused\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eAvailable Configurations — Where S755 Fits in the Castair Pump Lineup\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eS755 — 3.5 HP, I2 cylinder, 12\" flywheel, 16 oz. oil:\u003c\/strong\u003e Entry-level commercial pump — suits smaller single-phase motor setups and replacement pumps on 30–60 gallon tanks ($445.06)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVA80 — 4–5 HP, V2 cylinder, 12.5\" flywheel, 48 oz. oil:\u003c\/strong\u003e Step up in oil capacity and HP range — better for higher-demand single-phase applications with a larger tank ($1,800.56)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhen Does a Shop Need the S755 vs. Stepping Up or Down\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eThe S755 is right for you when:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eYour existing pump on a 30–60 gallon tank has failed and the motor and tank are still serviceable\u003c\/li\u003e\n  \u003cli\u003eYou are building a compact custom compressor for a specific 3–4 HP application\u003c\/li\u003e\n  \u003cli\u003eYou run a two-bay shop with intermittent air demand — impact wrenches, air ratchets, blow guns, tire inflation — not continuous spray painting or sandblasting\u003c\/li\u003e\n  \u003cli\u003eYou want a Cast Air pump at the entry price point\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eStep up to the VA80 when:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eYou need more oil capacity (48 oz. vs. 16 oz.) for longer run cycles\u003c\/li\u003e\n  \u003cli\u003eYour application is in the 4–5 HP range rather than 3–3.5 HP\u003c\/li\u003e\n  \u003cli\u003eYou are running spray equipment or DA sanders with extended duty cycles\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eConsider a complete compressor unit when:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eYour motor or tank is also at end of life — buying individual components adds up quickly at that point\u003c\/li\u003e\n  \u003cli\u003eYou need more than 5 HP — at that level, a Cast Air complete industrial-series unit is typically more cost-effective\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAuthorized Cast Air dealer since 2016\u003c\/strong\u003e — we know the lineup and can help match the right pump to your application\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e on qualifying orders\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree technical support\u003c\/strong\u003e — call 866-217-0063 before you order if you need help confirming flywheel sizing, belt selection, or pump-to-motor compatibility\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFull manufacturer warranty\u003c\/strong\u003e on every Cast Air pump we sell\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHonest guidance\u003c\/strong\u003e — if the S755 is not the right pump for your application, we will tell you before you order\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342600691925,"sku":"S755","price":820.76,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/CAST-IRON-BARE-PUMPS-WITH-FLYWHEEL_new_a73c41a0-105e-4dd0-8669-8103445a7b15.jpg?v=1772652923","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-3-5-hp-single-stage-i2-cylinder-air-compressor-bare-pump-with-12-flywheel-od-16-oz-oil-capacity-s755","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}