The original cylinder head that came on the waterboxer engine (83-91 Vanagon) is a German designed and made unit. It is no longer available new. About 15 years ago, in response to the growing demand, the AMC company of Spain started producing a replacement cylinder head for the waterboxer. 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. Who needs to know when a cylinder head was cast anyway? 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? Check out the above photos! Where the Spanish failed was in quality control. 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 see (when AMC heads are used straight out of the box) 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, we have not seen ANY AMC heads installed straight out of the box go over 60k miles without some kind of failure.
The GoWesty Solution!
Well, we take the highest-quality Spanish AMC cylinder heads 20-30 at a time and send them to the GoWesty machine shop here on the central coast of California. Our machine shop is run by second-generation, super-talented machinists Stephan and Travis. Their pop, Dave, is still there, too. These are the same guys who flow-tested these heads for us so we could come up with optimized cam grind profiles for all of the different sized engines we build (another GoWesty exclusive). These guys know what they're doing (a photo of the flow-test set-up is below). We remove all of the valves and scrap them, then replace them with new German-quality valves. 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 OE German quality intake and exhaust valves. It is simply a crime that our competitors 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 are a bargain.