{"product_id":"castair-replacement-motor-pulley-1-3-8-fixed-bore-shaft-6-75-od-2b-grooves-p2b675-13-8","title":"Castair Replacement Motor Pulley 1-3\/8\" fixed bore Shaft 6.75\" OD. 2B Grooves P2B675-13\/8","description":"\u003cp\u003eThe Castair P2B675-13\/8 is a 2-groove (2B) replacement motor pulley with a fixed 1-3\/8\" bore and 6.75\" outer diameter, designed for Cast Air belt-drive air compressor systems. This is the direct replacement when your original motor pulley shows groove wear, cracking, or physical damage from a thrown belt — and the motor shaft is 1-3\/8\".\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eNote: Cast Air did not provide a dedicated manufacturer product page for this pulley.\u003c\/strong\u003e Specifications are drawn from the product listing and standard 2B-groove pulley engineering conventions. Contact us to confirm fitment for your specific application.\u003c\/p\u003e\n\n\u003ch2\u003eUnderstanding the 2B Motor Pulley\u003c\/h2\u003e\n\u003cp\u003eThe 2B designation means two B-section V-belt grooves. B-section is the standard for compressor motor drives in the fractional to 5 HP range. Running two matched B-section belts instead of one distributes load across both groove surfaces, reduces belt slip during startup under load, and extends belt life — all of which matters in a shop where the compressor runs continuously. The 6.75\" OD determines your belt drive ratio; paired with the flywheel pulley on your Cast Air pump, it sets the pump RPM and therefore your delivered CFM.\u003c\/p\u003e\n\n\u003ch3\u003ePulley Specification Details\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGroove Profile:\u003c\/strong\u003e 2B (two B-section V-belt grooves)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBore Type:\u003c\/strong\u003e Fixed bore — 1-3\/8\" (1.375\") shaft diameter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Diameter (OD):\u003c\/strong\u003e 6.75\"\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Motor-side pulley for belt-drive air compressors\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Castair belt-drive compressor systems with 1-3\/8\" motor shafts and B-section belts\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e P2B675-13\/8\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eDrive Ratio and Pump Speed — Why OD Matters\u003c\/h2\u003e\n\u003cp\u003eMotor pulley OD and pump flywheel OD define your pump RPM. At 1,750 RPM motor speed, a 6.75\" motor pulley paired with a 14\" flywheel on the pump produces roughly 844 pump RPM — within the correct operating range for most Cast Air single-stage pump designs. Installing the wrong OD shifts the ratio, over-speeding the pump (wear, heat) or under-speeding it (CFM loss). Always verify the OD matches the original before ordering a replacement.\u003c\/p\u003e\n\n\u003ch3\u003eFixed Bore vs. Taper-Lock Pulley Selection\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixed bore pulleys\u003c\/strong\u003e (like the P2B675-13\/8) are machined for a specific shaft diameter and mount with a keyway and set screw. Correct for a direct swap when the original was also a fixed bore 1-3\/8\" unit.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTaper-lock (SK\/SD hub) pulleys\u003c\/strong\u003e use interchangeable bushings adapting to different shaft sizes. Better for installations where the motor may be replaced later, but not a direct swap for fixed-bore pulleys.\u003c\/li\u003e\n\u003cli\u003eIf the original pulley was fixed bore 1-3\/8\" and the OD was 6.75\", the P2B675-13\/8 installs as a direct replacement with no adapters or modifications.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhen Does a Shop Need This Pulley?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eExisting motor pulley shows cracked grooves, chipped flanges, or V-belt contact wear causing belt slip or belt throw\u003c\/li\u003e\n\u003cli\u003eMotor swap resulted in a 1-3\/8\" shaft — this pulley maintains the original drive ratio\u003c\/li\u003e\n\u003cli\u003eRebuilding a Cast Air belt-drive compressor to OEM specification\u003c\/li\u003e\n\u003cli\u003eCompressor pump RPM is measurably off (tachometer) and pulley OD has been identified as the cause\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003e2B Fixed-Bore 1-3\/8\" Motor Pulley Size Comparison\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eP2B625-13\/8 — 6.25\" OD — $68.34\u003c\/strong\u003e — smallest in the series; lower pump RPM for the same motor speed\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eP2B675-13\/8 — 6.75\" OD — $71.23\u003c\/strong\u003e (this unit) — mid-range OD, common on Cast Air mid-HP single-stage compressors\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eP2B80-13\/8 — 8.0\" OD — $88.55\u003c\/strong\u003e — larger diameter increases pump RPM; higher CFM on appropriate pump models\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eP2B875-13\/8 — 8.75\" OD — $103.95\u003c\/strong\u003e — largest fixed-bore option in the 1-3\/8\" bore lineup\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eMeasure your original pulley OD before ordering. If you are not sure which size your compressor uses, call us and we will identify the correct replacement for your Cast Air model.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e P2B675-13\/8\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGroove Type:\u003c\/strong\u003e 2B (two B-section V-belt grooves)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBore:\u003c\/strong\u003e Fixed, 1-3\/8\" (1.375\")\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOuter Diameter:\u003c\/strong\u003e 6.75\"\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBore Style:\u003c\/strong\u003e Fixed (keyway and set screw)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBelt Section:\u003c\/strong\u003e B-section (two matched belts)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $71.23\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Data:\u003c\/strong\u003e Product page not available — specifications from product listing data\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat Is Included\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1x Castair P2B675-13\/8 motor pulley\u003c\/li\u003e\n\u003cli\u003eSet screw(s) for shaft retention\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eB-section matched belts are not included. Order separately based on your drive center distance.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h2\u003e\n\u003cp\u003eWe have been sourcing and selling Cast Air compressor parts since 2016. We stock the motor pulley lineup across OD sizes so you get the right part without guessing. Free shipping on every order. Our tech support team can confirm fitment for your specific Cast Air model before you place your order — no automated call centers, just people who know compressor drive systems.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCast Air specialist\u003c\/strong\u003e since 2016\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e on every order\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree tech support\u003c\/strong\u003e — call to confirm fitment before ordering\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull manufacturer warranty\u003c\/strong\u003e on all parts\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHonest parts guidance\u003c\/strong\u003e — we will steer you to the correct OD for your application\u003c\/li\u003e\n\u003c\/ul\u003e\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":53342573658325,"sku":"P2B675-13\/8","price":132.06,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/MOTOR-PULLEYS-300x248_67d37c02-13b8-42ce-8532-a1ebcd27b723.jpg?v=1772652773","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-replacement-motor-pulley-1-3-8-fixed-bore-shaft-6-75-od-2b-grooves-p2b675-13-8","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}