Aluminum heads must be treated differently than their cast iron counterparts.
Aluminum heads have their own quirks when it comes to servicing them. Since aluminum heads have been designed for their light weight and heat dissipating qualities, they have a tendency to expand and contract much more than cast iron heads. Removing valves from an aluminum head requires certain precautions since the material that seats the valve can become distorted or even ruined if not handled properly.
Carburetor Cleaner
Any time an aluminum head has been removed it will contain carbon buildup in the combustion chambers, including varying accumulations of carbon in the valve guides. Cleaning the head completely will remove all varnish and carbon deposits that can impede removal of the valve train parts. A stiff-bristled engine cleaning brush and carburetor cleaner works best to get in all the nooks and passages that need to be cleaned.
Penetrating Oil
Equally important to cleaning the head will be the liberal application of penetrating oil. Penetrating oil comes in spray or spout type applicators. Either version will work so long as liberal amounts are applied to all of the valve train parts, in particular, the valve stem area where it enters the head. The oil must be allowed to sit and penetrate through the minute cracks for at least 30 minutes.
Valve Spring Compressor
The valve spring compressor has a C-shaped clamp design with an adjustable handle so that the valve spring can be compressed. The spring clips that hold the valve in place can only safely be removed by shoving the spring down against its seat, relieving the pressure on the retaining clips. Once the clips have been removed, the spring comes off, exposing the valve stem shaft.
Valve Extraction
The head should be placed on a flat surface (combustion side down) with wooden blocks supporting each end. You need to allow clearance to remove the valves. A small hammer, ball peen or large tack hammer can be the best tool to shock the valve stem loose. By tapping downward on the top of the valve stem, it will move downward within the guide and exit the head from the valve seat hole. Several taps may be required, with the addition of more penetrating oil on the shaft, or even some motor oil or grease.
Heat Assist Technique
If for any reason the valve stem refuses to move after tapping and additional penetrating oil, you can try the heat assist removal method. First, the head must be cleaned again and wiped clean of any and all cleaner fluid. A propane torch held on the top of the head around the valve guide will expand the aluminum enough to loosen the valve stem. Steady and concentrated heat must be applied. Tapping with a hammer, while heating, should break the valve stem loose from its guide.
