These heads receive our Stage I Performance Valve Job, 1.850” O.S. Valves, new guides and 7mm conical springs. The head gasket surface will be skim decked to assure a true/flat sealing surface. This is a high quality upgrade for a budget build! Combustion chambers are stock 78 to 83 cc.
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.
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.
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 Baisley 1.840” intakes and 1.615” exhausts with Viton seals, while new valve springs 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.
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.
Special high velocity port design with 1.850/ 1.610 valves. Valves and
7mm conical springs. Designed for engines with factory or aftermarket flat top
pistons or dome pistons. The combustion chambers are 78 cc to 82 cc range as
cast.
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.
Owners of Evolution® powered Big Twins can increase their engine’s output with a set of our CNC-ported EV heads! The factory casting is CNC-machined to our proven high torque, high power port shapes and the valve sizes are increased to 1.900” intake and 1.630” exhaust. Ductile iron Step-Lock guides are fitted and topped off with high quality Viton® seals and a performance spring kit. The head gasket surface is decked for flatness before final assembly.
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.Click Here to complete your Job Order Sheet.
