{"product_id":"balmar-48-wsp-18-westerbeke-serpentine-pulley-kit","title":"Balmar Pulley Kit, Westerbeke 18, 21A, 27A, 35B, 38B, 42B","description":"\u003cp class=\"nvn-hero\"\u003eThe Balmar 48-WSP-18 is an AltMount serpentine pulley conversion kit for Westerbeke 18, 21A, 27A, 35B, 38B, and 42B diesels. It swaps the stock single-groove drive for a ten-groove J10 system so your alternator finally gets the grip to put out full amps without slipping a belt.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eIf you've fought a slipping V-belt on a Westerbeke diesel while trying to run a real charging load, this Balmar AltMount kit is the fix. It's a serpentine pulley conversion that swaps the stock single-groove setup for a ten-groove J10 system, so your alternator finally gets the grip it needs to put out full amps without smoking a belt.\u003c\/p\u003e\n\u003cp\u003eThe 48-WSP-18 covers a wide range of Westerbeke engines: the 18, 21A, 27A, 35B, 38B, and 42B. It actually replaces five older single-model Balmar kits (the 48-WSP-21A, 27A, 35B, 38B, and 42B), so one part number now does the work of the whole family. In the box you get three ten-groove (J10) pulleys, two J10 40-inch serpentine belts, and the mounting hardware to bolt it all up. One of those belts is a spare, which is exactly what you want tucked in a locker on a cruising boat.\u003c\/p\u003e\n\u003cp\u003eWhy serpentine? A ten-rib belt wrapping a wider pulley face carries a lot more load than a narrow V-belt riding in a single groove. That means less slip, less belt dust, and cooler running when you've got a high-output alternator pulling hard at anchor. Balmar's own testing on the AltMount line shows a clear improvement in power transfer along with lower noise and less engine vibration. On a sailboat where you're charging a big house bank off the main engine, that's the difference between keeping up and falling behind.\u003c\/p\u003e\n\u003cp\u003eThis kit is the natural partner for a Balmar high-output alternator upgrade. If you're stepping up from a stock 55-amp unit to a 6-Series charging 100 amps or more, the stock belt will slip under that load. The serpentine setup handles it. Pair the alternator with the right Balmar external regulator so the whole system charges hard without cooking itself, and you've got a charging package that actually earns its keep on a long passage.\u003c\/p\u003e\n\u003cp\u003eWho's this for? Mostly cruising sailors and trawler owners running one of these Westerbeke blocks as auxiliary power. If you've added a bigger battery bank, moved to lithium, or you're just tired of topping off with the engine for hours, upgrading the alternator drive is one of the highest-value moves you can make in the engine room. The pulley kit is the foundation the rest of that upgrade sits on. Skip it, and even the best alternator can't deliver what it's rated for.\u003c\/p\u003e\n\u003cp\u003eA couple of install notes from the field. Clean the crankshaft pulley groove before you set the new pulleys so the belt seats right and wears evenly. Torque the pulley set screws down and hit them with thread locker, because a set screw that backs out at sea is a bad afternoon. Check your belt alignment across all three pulleys with a straightedge before you tension it. And one spec-sheet detail worth flagging: if you're specifying a Balmar AT-200A alternator, you may need a longer belt than the two 40-inch belts in this kit, so plan for that when you order.\u003c\/p\u003e\n\u003cp\u003eKeep that spare belt aboard. Serpentine belts are reliable, but they're a wear item, and a marine store two towns over may not stock a J10 40-inch belt when you need it. Having the exact match already in your spares kit means a ten-minute swap instead of a ruined weekend.\u003c\/p\u003e\n\u003cp\u003eThis isn't a dress-up part. It's a working upgrade for boaters who ask their engine to charge like it means it. If your Westerbeke is on that list and you're tired of chasing belt slip, this is the kit that ends it. Give us a call if you're not sure it matches your engine, we'll help you confirm before you buy.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eAltMount serpentine conversion replaces the stock single-groove drive with a ten-groove J10 system for far better power transfer and less belt slip\u003c\/li\u003e\n  \u003cli\u003eFits Westerbeke 18, 21A, 27A, 35B, 38B, and 42B diesel engines from one part number\u003c\/li\u003e\n  \u003cli\u003eIncludes three ten-groove (J10) pulleys machined for the serpentine belt path\u003c\/li\u003e\n  \u003cli\u003eShips with two J10 40-inch serpentine belts, one of them a spare to keep aboard\u003c\/li\u003e\n  \u003cli\u003eReduces engine noise and vibration compared to a slipping V-belt drive\u003c\/li\u003e\n  \u003cli\u003eHandles the load of a Balmar high-output alternator upgrade without slipping\u003c\/li\u003e\n  \u003cli\u003eMounting hardware included for a complete bolt-on conversion\u003c\/li\u003e\n  \u003cli\u003eReplaces five older single-model Balmar kits: 48-WSP-21A, 27A, 35B, 38B, and 42B\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized Balmar reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhich Westerbeke engines does this kit fit?\u003c\/summary\u003e\n    \u003cp\u003eThe 48-WSP-18 covers the Westerbeke 18, 21A, 27A, 35B, 38B, and 42B diesel engines. If you're not sure which block you have, give us a call with your engine model and serial and we'll confirm the fit before you order.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat comes in the box?\u003c\/summary\u003e\n    \u003cp\u003eThree ten-groove (J10) pulleys, two J10 40-inch circumference serpentine belts (one is a spare), and the mounting hardware needed to complete the conversion.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhy convert to a serpentine belt at all?\u003c\/summary\u003e\n    \u003cp\u003eA ten-rib serpentine belt on a wider pulley face grips far more than a narrow V-belt in a single groove. That means less slip, less belt dust, and cooler running when a high-output alternator is pulling hard. Balmar's AltMount line is built to improve power transfer while cutting noise and vibration.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDo I really get a spare belt?\u003c\/summary\u003e\n    \u003cp\u003eYes. Two 40-inch J10 belts ship in the kit and one is meant to live in your spares locker. A serpentine belt is a wear item, and the exact J10 40-inch size isn't something every marine store stocks, so having the match aboard turns a breakdown into a quick swap.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan I run a high-output alternator with this kit?\u003c\/summary\u003e\n    \u003cp\u003eThat's exactly what it's for. When you step up from a stock 55-amp unit to a Balmar 6-Series charging 100 amps or more, the stock V-belt slips under load. The serpentine drive handles the extra grip. Pair it with the correct Balmar external regulator so the system charges hard without overheating.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat belt do I need if I install a Balmar AT-200A alternator?\u003c\/summary\u003e\n    \u003cp\u003eHeads up on that one. If you specify an AT-200A alternator, you may need a longer belt than the two 40-inch belts included here. Plan for the different belt length when you order so you're not caught short during the install.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDoes the kit include mounting hardware?\u003c\/summary\u003e\n    \u003cp\u003eYes, the mounting hardware for the conversion is in the box. A few field tips: clean the crankshaft pulley groove before setting the pulleys, use thread locker on the set screws, and check belt alignment across all three pulleys with a straightedge before tensioning.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat older part numbers does this replace?\u003c\/summary\u003e\n    \u003cp\u003eThe 48-WSP-18 supersedes five older single-model Balmar kits: the 48-WSP-21A, 48-WSP-27A, 48-WSP-35B, 48-WSP-38B, and 48-WSP-42B. One kit now covers the whole Westerbeke range those parts used to serve.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow is warranty and returns handled?\u003c\/summary\u003e\n    \u003cp\u003eThis item carries the full Balmar manufacturer warranty. Because of how it's stocked, warranty questions and any concerns are handled manufacturer-direct rather than returned to the point of purchase, and we're happy to help you get in touch if anything comes up.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eBalmar Pulley Kit, Westerbeke 18, 21A, 27A, 35B, 38B, 42B\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eBalmar\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003e48-WSP-18\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e676205510080\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eSystem Type\u003c\/th\u003e\n\u003ctd\u003eAltMount Serpentine Pulley Conversion Kit\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eEngine Compatibility\u003c\/th\u003e\n\u003ctd\u003eWesterbeke 18, 21A, 27A, 35B, 38B, 42B\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003ePulleys Included\u003c\/th\u003e\n\u003ctd\u003eThree Ten-Groove (J10) Pulleys\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBelts Included\u003c\/th\u003e\n\u003ctd\u003eTwo J10 Serpentine Belts (one spare)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBelt Groove Profile\u003c\/th\u003e\n\u003ctd\u003eJ10 (Ten-Groove)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBelt Length\u003c\/th\u003e\n\u003ctd\u003e40 inch Circumference\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eMounting Hardware\u003c\/th\u003e\n\u003ctd\u003eIncluded\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eReplaces\u003c\/th\u003e\n\u003ctd\u003e48-WSP-21A, 48-WSP-27A, 48-WSP-35B, 48-WSP-38B, 48-WSP-42B\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003ctd\u003eMarine Diesel Engine Alternator Drive\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eCategory\u003c\/th\u003e\n\u003ctd\u003eElectrical \/ Alternators\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Which Westerbeke engines does this kit fit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The 48-WSP-18 covers the Westerbeke 18, 21A, 27A, 35B, 38B, and 42B diesel engines. If you're not sure which block you have, give us a call with your engine model and serial and we'll confirm the fit before you order.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What comes in the box?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Three ten-groove (J10) pulleys, two J10 40-inch circumference serpentine belts (one is a spare), and the mounting hardware needed to complete the conversion.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Why convert to a serpentine belt at all?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"A ten-rib serpentine belt on a wider pulley face grips far more than a narrow V-belt in a single groove. That means less slip, less belt dust, and cooler running when a high-output alternator is pulling hard. Balmar's AltMount line is built to improve power transfer while cutting noise and vibration.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Do I really get a spare belt?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. Two 40-inch J10 belts ship in the kit and one is meant to live in your spares locker. A serpentine belt is a wear item, and the exact J10 40-inch size isn't something every marine store stocks, so having the match aboard turns a breakdown into a quick swap.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I run a high-output alternator with this kit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"That's exactly what it's for. When you step up from a stock 55-amp unit to a Balmar 6-Series charging 100 amps or more, the stock V-belt slips under load. The serpentine drive handles the extra grip. Pair it with the correct Balmar external regulator so the system charges hard without overheating.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What belt do I need if I install a Balmar AT-200A alternator?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Heads up on that one. If you specify an AT-200A alternator, you may need a longer belt than the two 40-inch belts included here. Plan for the different belt length when you order so you're not caught short during the install.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Does the kit include mounting hardware?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes, the mounting hardware for the conversion is in the box. A few field tips: clean the crankshaft pulley groove before setting the pulleys, use thread locker on the set screws, and check belt alignment across all three pulleys with a straightedge before tensioning.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What older part numbers does this replace?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The 48-WSP-18 supersedes five older single-model Balmar kits: the 48-WSP-21A, 48-WSP-27A, 48-WSP-35B, 48-WSP-38B, and 48-WSP-42B. 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