- New cast iron cylinder head from new patternwork based on the original Holbay design
- Options for fully finished with ports and chambers polished or part finished with no porting work completed
- Inlet seat cut directly onto the cast iron to suit a 1.40” diameter valve
- Exhaust seat cut on a sintered insert to suit a 1.25” diameter valve
- Colsibro valve guides finished for 9/32” valve stems fitted if fully finished, provided ready to fit if part finished.
- Combustion chamber machined and hand polished with a nominal chamber volume of 16.5cc
- Standard 10mm spark plug
- All core plugs fitted
- Fully pressure tested prior to dispatch
| Port & Chamber | Unfinished, Fully Ported |
|---|









