Cylinder Heads for Waterboxers: The Full Story

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. Other unrelated quality issues can and do pop up from time to time. For example, we once got an entire shipment with defective valve guides that disintegrated within a few thousand miles of installation—we had to recall several engines for this problem. Most recently in May 2020 we got a shipment of heads that were not up to their own specification with regard to cylinder bore depth, and definitely not up to the specifications we demand for our engine program. The AMC corporation has always stood behind their heads, and responded quickly when issues have been brought to their attention—and they always fix the problem. But for our engine program, we simply cannot afford to use one of these heads “out of the box” and risk the possible consequences. 

The GoWesty Solution!

We purchase AMC cylinder heads directly from the source in bulk, as complete assemblies, ready to bolt on. These AMC-built heads we sell are no different than what you can get anywhere else (they never even get taken out of the box!), except for the price—we buy directly from AMC, so we've got everyone beat there! We also offer AMC heads we modify.

The GoWesty-built AMC head process includes:
• Unbox and completely disassemble
• Measure valve guide clearance
• Measure valve seat eccentricity: three angle valve grind if/as needed
• Measure cylinder counter bore depth
• Blend valve seat to combustion chamber with a radius cutter in the seat and guide machine
• Sand/blend between valve seats and around spark plug
• Measure and polish valve stems
• Face valves
• Final clean all parts and re-assemble

What we end up with is a cylinder head that is better than the AMC-built cylinder head assembly, and miles better than the original Volkswagen example in all regards.