Add Torque and Power to any production Twin Cam® or Evolution® head with our WorkHorse blueprinting service. After cleaning and Step-Lock guide installation and fitment, proprietary seat and valve machining improves flow and ensures a positive seal by truing now heat-seasoned seats and removing typical production chatter that leads to leaks between the seat and valve. This process improves even new, low mileage heads on engines that are being upgraded with cams or big bore kits. Valves are upgraded to 7mm coated stainless 1.850” intakes and 1.610” exhausts with Viton seals, while new lightweight beehive valve springs with chrome-moly retainers and keys are set up for cam selection provided. Head gasket surfaces are skimmed to ensure absolute flatness. This Stage I head delivers a true, high quality “budget upgrade” for any engine, while updating 1984-2004 cylinder heads to modern, lightweight 7mm components.

Stage I WorkHorse headwork is performed on supplied head cores; in-house shop time is 3-7 working days.

Exchange heads may be available if the condition of your cores qualifies. You can also purchase heads outright (without supplying a core set). We will supply clean, reconditioned factory castings for your application – add part #517-015 to your order.

International Customers – Import duties are not required when to shipping your castings for modification. Special low shipping rates are available for your cores; contact your sales representative for details.

Remove heads from engine, wash off oil and ship to Zipper’s as-is. Improper cleaning methods can actually do more harm than good; we suggest you allow us to properly prepare your heads for modification. Extreme care is taken during our preparation process to preserve component finishes. A small cleaning charge applies to heads sent in for modification.



Zipper’s Job Order Sheet

Weight 1 lbs

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