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Zipper’s Stage 3.5 CNC for 06+ TC w/ACR

The Zipper’s Performance Stage 3.5 heads with Automatic Compression Releases have a special high flow port design that is one of the largest we can machine into an O.E castings. Special O.S. 2.00” valves, Step Lock Guides, special valve seat machining, 5/16” dual spring for lift up to .675”. These are maximum output heads and are a good option Vs purchasing CVO castings with the added expense of porting. Combustion chambers are 92 cc.

*Not available for Twin Cooled Models

Processing time

Once the cores arrive at Zipper’s they are unboxed, and inspected for shipping damage. Then we review your job order sheet and other related documentation. Job sheets that have not been finalized before your cores arrived will take additional time to sort thru before the job is put into production. Once finalized, the cores will be disassembled, serialized then move into production. Turn around (Process time) varies depending on the time of the season and how long it takes to get your job sheet finalized. Because of the dedicated skilled labor at Zippers and the vast amount of capital equipment we get the work completed with the highest standard of quality with one of the best turnaround time in the industry.

Work is performed on your supplied head cores.

For our standard production heads Shop Time is approximately 15 business days (during peak season allow for additional time).  The below options will require additional time to process:

    • Custom Modifications
    • Custom Finishes
    • Require Thermal coatings
    • Needing Additional Repairs
    • Or other Non-Standard Work

Exchange heads may be available if the condition of your cores qualifies. The process to determine the condition of your cores is to ship your cores to Zippers for inspection.

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.

Supply us with your piston volume and camshaft selection for final cc volume through decking.

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.

*To ensure you enjoy a premium experience, Please fill out a Build Sheet/Job Order Sheet prior to completing an order on the website.
Click here for Zipper’s Build Sheet/Job Order Sheet

Not legal for sale or use in California on any pollution controlled motor vehicle.
Not legal for sale or use on any EPA pollution controlled motor vehicle.

Weight 27 lbs
Dimensions 1 × 1 × 1 in
Engine Type