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This is the head we using on our Pro Drag SR20.

Here at Mazworx, we can build your cylinder head to your specifications. Utilizing our CNC capabilities and state-of-the-art equipment, you can ensure that the machining process is done properly. If you want a cylinder head that is ready-to-bolt-on, see the specifications section for info. For more understanding of our process, see the additional information section.

Each built head will start with the following:

Hot Tank Cleaning:
Wash your head to get oil and grim off.

Sand Blast Head:
Since these heads can be over 20 years old, they may start corroding. Sand blasting the block will get the corrosion/debris off, bring a uniform satin aluminum color to the head and give it an overall better look.

R/R Oil Port Plugs/Freeze Plugs:
This process includes removing, re-tapping, and reinstall all the oil port plugs. By taking out the oil port plugs, we are better able to clean all the oil galleys. The freeze plugs are also removed and

Shimless Valves:
Nissan sets the last using shims between the valve and rocker.  At high rpm or while on the rev limiter, these are known to come out and possible cause damage.  The shimless valves are made to get rid of that shim.

Port and Polish:
Stage 4 port is a developed level CNC port. We maximize the ports and seat to obtain the highest flow. We invest hours developing this port using our Superflow 600 flow bench.  This port is increased in size and will match our Pro Drag SR20 Intake Manifold.

CNC 90mm Combustion Chamber:
This process opens up your combustion chamber and removes the squish areas. The squish areas are there for low rpm tumbling of the air fuel mixture, but at high boost, they become a hot spot. This leads to detonation. Plus opening up the chamber deshrouds the valves and allows them to breath better.
The process can be viewed here: Mazworx CNC Combustion Chamber

R/R/R Valve Guides:
This process removes, re-installs, and reams the valve guides. The guides are replaced with Supertech bronze valve guides. For port and polish stages 2 & 3, this process will need to be done

Copper Alloy Valve Seats:
When running high boost and methanol, OEM iron seats are not the way to go.  Plus these seats are increased in size to accommodate the larger valves.

Multi Angle Valve Job:
In this process, we cut multiple angles in the valve job to help increase flow. With a 90mm chamber, we can add up to 5 angle plus a radius.

1/2" Head Stud Machining:
The head stud holes are drill to fit 1/2" head studs and the dowel pin locations are machined for 16mm dowels.

Resurface your head using a PCD (poly-crystalline diamond) tool.

Valve Seals:
Replacing your old valve seals with new ones.

Installation of the valve, springs, and retainers.

Set Lash:
This process we will set the valve lash to the camshaft's specifications.

Parts Included:
Mazworx 36mm Intake and 32mm Inconel Exhaust Shimless Valves
Supetech Titanium Retainers
Supertech Dual Valve Springs, 123lb
Supertech Bronze Valve Guides
Ferrea Billet Valve Locks
Kelford 184-X Pro Drag SR20VE VVL Killer Cams
Viton Valve Seals
Oil Port Pipe Plugs
Threaded Freeze Plugs


If you plan on sending in your head, we will wait for your head to show up before work is started. If you don't have a head and want to purchase a core, then please.