Replacing or restoring the cylinder head for a Lotus-Ford Twin Cam (as found in the Elan, Lotus Cortina, and Europa) is a common crossroad for classic owners. Given the age of original castings, many are now suffering from excessive “skimming” (reduction in height) or internal corrosion.

1. New Aftermarket Castings

Modern metallurgy and CNC machining have made new heads a superior choice for many restorations. Most new heads are cast in LM25TF aluminum, which is stronger and more thermally stable than the original 1960s material.

• QED Motorsport: They are the primary holder of the original Lotus tooling. Their heads are cosmetically identical to the late-production (1967–1974) units and are stamped with the original Lotus part numbers.

  • Price: Starting from £2,275 for a bare casting.

• Mountune USA / SAS Engineering: These manufacturers offer heads that eliminate the need for cam bearings by machining the bores directly into the head (like modern engines).

  • Price: Approximately $5,900 for a fully machined head with seats and guides.

• Burton Power: They stock the “FL830” bare casting, often used for 1558cc Sprint-spec builds.

2. Identifying Your Original Head

If you are evaluating a used unit, the casting marks reveal its origin and performance potential:

• Weber vs. Stromberg: Heads for Weber/Dellorto carburetors have four separate inlet ports. Stromberg heads (emissions-spec) have “siamesed” inlet ports (two shared openings).

• “L” Stamping: Found on a raised boss near the No. 1 spark plug. This indicates a later “Big Valve” or “Sprint” head, which typically featured larger 1.56″ inlet valves.

• Thickness Check: A critical measurement. A factory-fresh head is 4.650 inches thick. If a head has been skimmed below 4.625 inches, it may require special thicker head gaskets or shortened timing chains to work.

3. Comparison of Replacement Options

Final Recommendation

For a high-performance or race build, a new casting from QED or Mountune is the safer investment; it guarantees a full life-cycle and superior flow. However, for a numbers-matching concours restoration, sourcing a period-correct original casting (approx. $800–$1,500 for a core) and sending it to a specialist for a “long-stud” conversion and unleaded valve seats is the preferred path.