Now before we get to into it, let’s examine exactly what a “3 angle valve job” actually is. A 3 angle valve job is the process of machining the contact area of the underside of the valve, so that the mating surface is smaller or sharper, and making the seat angle greater. This allows the valve to seal faster and more tightly. This also increases port turbulence, which increases air speed, allowing more air into the mix.

One reason why it is important to have a good machinist is that by changing the angles and size of the valve contact patches, you can change the “agressivenes” of the valve job. A more drastic valve job will have higher gains, but at a cost. Valves dissipate heat during their closed state. When the valve is closed, it is in contact with the cylinder head, and the heat is transfered. This issue with heat transfer is why titanium valves were introduced. Titanium valves provide ultimate thermal protection, and decreased maliability under stress.

Another thing to consider when doing any kind of cylinder head modifications is that entire valve train is designed to work as a system. The tolerances, valve lashes, spring tensions, etc, are all designed so that everything runs on harmony. When changing any part, you need to be careful and make sure that everything is compatible. I personally recommend the all or nothing approach. Many street cars will be just fine with stock head work. If you’ve got a spare head, and want to bring your car to the next level, i say go for it. But you can’t just throw in super aggressive cams, or get a 3 angle valve job by itself.

The best thing to do is make friends with a local machine shop. They will have more knowledge than you will know what to do with!