The original cylinder head that came on the waterboxer engine (1983-91 Vanagon) is a German designed and made unit. It is no longer available new from VW, but there is a better aftermarket example made by the AMC company of Spain. The casting they produce is superior to the original German-made casting. It has 8% more mass than the original casting (weighs 12.2 lbs. versus the 11.4 lbs. of the original design). The new Spanish casting is thicker in areas where the original casting was known to fail, namely near the spark plugs at the date-code stamping. It is interesting and amusing how German engineers—whom are renowned for their engineering prowess—actually weakened an otherwise bulletproof cylinder head design because of their obsession with documentation. Needless to say, the somewhat more pragmatic Spanish re-producers dispensed with the date stamping, and added extra material there for good measure.
So what's the problem?
Where the Spanish failed from the onset was in regard to quality control of the parts they used and the workmanship. Specifically, the valves used—and the valve job (grinding of the valve seats and valve faces)—were both very, very poor. The photo above (left) is of an intake valve removed from an AMC cylinder head with 29,782 miles on it. The failure occurred when the keeper grooves at the top of the valve sheared off. So, instead of the valve being pulled back by the valve springs, it kept going into the engine where it had an unpleasant meeting with the piston that was on its way back up. The other failure we typically saw when these heads originally hit the market takes place at the other end of the exhaust valve. Since the exhaust valve is smaller and lighter than the intake valve, the stresses at the top between the keepers and keeper grooves is not as high as with the intake valve. Thus, they often succumb to a different, less exciting demise. A combination of poor valve quality and imprecise grinding causes the exhaust valve to allow superheated exhaust gasses to escape during combustion, which leads to the exhaust valve face "burning" prematurely (see photo above, right). Indeed, when AMC heads were originally launched and installed straight out of the box, they would typically not go over 60K miles without some kind of failure. Over the years, they have improved—but are still not quite up to par with the standards we require for our rebuilt engines.
The GoWesty Solution!
We purchase AMC cylinder heads in bulk and bare—just the castings with guides and seats installed, no other parts. We use our own, German-quality valves and related parts. We smooth the ports just past the valve seats for better air flow, perform a super quality three-angle valve job, and install brand-new OEM-quality intake and exhaust valves. The heads that go on our 2700cc engines get 1mm larger valves and some additional port work for the demands of the larger displacement. Our engine dynamometer testing showed this added work did not result in any improvement in performance on the smaller displacement engines, so only the 2700 gets this extra treatment. But in all cases, we end up with a cylinder head that is better than the original Volkswagen example in all regards. It is said "you get what you pay for," but that is not always the case. It is simply a crime that most folks sell these cylinder heads straight out of the box and purport them to be satisfactory, in some cases for the same price we sell ours! So, bottom line, at $0-150 each more than our competitors, GoWesty's cylinder heads represent money very well spent.