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Top End Components

Unlock the hidden potential of your engine with powerful Top End upgrades from Zipper’s Performance Products. Zipper’s Performance keeps specially CNC-machined heads in stock for super-quick turnaround (on an exchange basis) for Twin Cam® and Sportster® engines. Twin Cam® big bore cylinder conversions for 88 to 95” and 98" plus 96 to 103” and 107" fitted with forged pistons in many different compression ratios for fast turnaround or exchange. Zipper’s Performance also stocks pistons, valves, guides, valve spring kits, and other critical top end parts from the industry’s most renowned manufacturers.
  1. Be the first to review this product

    From: $13.50

    To: $67.50

    We’ve never been big fans of the shoulderless valve guides used by the factory in EV & TC heads, so we designed our own. Our ductile cast iron Step-Lock guides have a shoulder that helps set the guide to the correct depth, and, in the event that the engine is severely overheated causing the guide to come loose in the head, allows the lower valve spring collar to capture it, keeping it in place. The top side of the guide is machined to accept larger .531" ID seals while the port side is tapered to enhance flow around the guide. Requires use of stepped lower valve spring collars (our Crane spring kit collars work fine without modification). We offer lower collars to fit the spring kits we sell for use with these guides. Sold each.
  2. Be the first to review this product

    From: $12.25

    To: $1,044.00

    AV&V’s CNC-machined valve guides are made from Manganese bronze alloy which allows tighter clearances for improved heat dissipation, quiet operation and long life.
  3. Be the first to review this product

    From: $10.49

    To: $63.41

    AV&V’s valve seals are made from a special Viton compound that can resist higher temperatures than standard Viton seals. Manufactured to fit tighter on the guide – stays put! For this reason we recommend AV&V’s Valve Seal Driver tools for installation.