How to Rebuild a 911 Cylinder Head. Lesson 4, Valve Guides

Measuring a Valve Guide

911 Valve Guides The valve guides in the Porsche 911 Cylinder heads are consumable. The guides will also experience a lot of wear. There is constant friction between the guide and valve stem and the valve-train geometry puts even more side pressure on the guide. Porsche has always used a bronze guide. The bronze has […]

How to Rebuild a 911 Cylinder Head. Lesson 3, Valve Springs

Valve Spring in the head

Air-Cooled 911 Valve Spring Valve springs control the valvetrain. It is valve spring pressure that forces the valves to stay in contact with the rocker arm. Without the proper spring pressure, the valvetrain becomes uncontrollable. Not enough pressure and you can get valve float when the valvetrain gear loses contact with the camshaft lobe. Too […]

How to rebuild a 911 Cylinder Head. Lesson 2, Intake and Exhaust Valves

Dirty intake and exhaust vales on the bench waiting to be cleaned

Intake and Exhaust Valves This is Lesson Two from an Eight part series. In Lesson One, we covered the cleaning and disassembly of the cylinder head. In this lesson, we are all about the intake and exhaust valves. When the valves first come out of the heads they are very crusty. There can be a […]

How to Rebuild a 911 Cylinder Head. Lesson 1

How to rebuild the 911 Cylinder head Part 1

When it comes to the Porsche 911 cylinder head you will rarely find a set that has been untouched. Follow along with this 8 part series to fully understand the air-cooled 911 cylinder head.

How to calculate Engine Compression

Engine Heads ready for volume measurement

Why do you need to Calculate Engine Compression? Any time that you make a change to an engine by machining the crankcase or machining the cylinder heads you change the compression relationships. If you change the relationship, you need to calculate engine compression. Today with the limited availability of original pistons and cylinders the use […]