Many Porsche enthusiasts are of the opinion that the air-cooled Mezger engine is the zenith of all Porsche production powerplants. A position that is hard to argue with. They are truly special units. We have been working with the cylinder heads from these wonderful engines for decades. We offer performance upgrades, flow testing, twin plugging and all heads, whether bone stock or wild race heads, receive the same highly detailed service. Our stated mission is the same with these heads as with all heads that leave our shop: that you will have zero details to tend to before installing your heads. They are shipped in plastic bags to keep them clean and ready to go.
Given the special nature of these engines, we offer a comprehensive reconditioning of the heads that addresses the typical problem areas of heads of their advanced age.
Our optional exhaust studs service is a major component of this reconditioning. It starts by removing all of the old studs and installing 304 stainless steel Genuine Heli-Coils (no knock off brands!) to eliminate the crusty old aluminum threads, creating strong permanent threads. This work is performed on one of our milling machines utilizing a custom BHJ fixture and Genuine Heli-Coil taps per Heli-Coil engineering guidelines. While set up for this process we then reface the exhaust gasket surfaces for a leak-free exhaust connection. This service includes new class 8.8 zinc plated studs. It’s the cat’s meow and you’ll be happy you opted for it when you’re under the car bolting the exhaust system in place.
It the spark plug threads are in poor shape, utilizing the same BHJ fixture we machine the heads for 304 S.S. Genuine Heli-Coils.
All heads get new super durable silicon-manganese bronze valve guides, exhaust valves and unless the application calls for performance upgrades, new Genuine Porsche springs. If the intake valves pass inspection, we’re comfortable reusing them. They have proven to be durable.
If this is a performance build oversized stainless-steel valves and port work is available.
Valve seats are machined with Serdi tooling.
Cylinder surfaces are CNC fly-cut to a ht. tolerance of .0001″ after careful detailing of the cam housing surfaces to ensure they’re clean and burr free. We also chase the cam housing stud threads to ensure trouble free assembly.
Valve stem ht’s are set to factory ht’s to ensure proper valve train geometry.
The finished heads are ready to bolt on right out of the box with no additional details required.
Scroll through our photo gallery for many more examples of our work with aircooled 911 heads. Samples Of Our Work
Street 2.7 heads that we twin plugged. These will sit on 2.9 Nickies cylinders and be fitted with Clewett ITB’s and SC cams.
Port-matched intakes for Clewett’s ITB’s.
A close-up view of the second plug machine work looking down through the fins.
What we started with. These heads were very tired. Severely worn guides, a couple burned exhaust valves.
hamheads.com 