Zipper’s 80/80 Evolution® Big Twin Kit

Zipper’s 80/80 kit for Evolution Big Twins is still as popular as ever! Its roots go back to the 80’s, and we named it 80/80 due to the fact that it easily delivers over 80 HP from 80”. Your cylinder base and head gasket surfaces are both decked true to stop those pesky leaks that EV’s are known for. We precision-fit forged 10.5:1 pistons to them. Your heads receive CNC porting to Zipper’s Stage III with 1.900” intake and 1.630” exhaust valves riding in Step-Lock guides with new valve springs and viton seals. Our Red Shift 559 cam is included with a new full compliment cam bearing; a steel breather gear replaces the factory plastic gear, and shims are included to set the end play on the cam and breather gear. Pro-taper pushrods control the valves and a top end/cam chest gasket set is included.

Processing note: Due to casting variations on early 80’s heads, we may elect to add and dress a little welding to the spark plug side of the heads to prevent porting cut-through.

This kit has remained a popular choice because it flat-out WORKS!

This kit uses your factory head & cylinder cores sent in for modification

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.

***To ensure you enjoy a premium experience with a Zipper’s Engine Kit, Please fill out a Job Order Sheet prior to completing an order on the website.
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