The Tillotson JT-207 has been modified from 25/24mm to 27/25mm diameter valves, and 5.5mm to 5mm valve stems improve flow. 

This head is the same used on the Tillotson 212R and coming 225RS engines. This makes a great replacement for the Predator Hemi engines gaining as much as .6:1 compression from just changing heads. Typical Predator Hemi is around 8.2:1. This head will bump it up to 8.81:1.

• Intake Valve: 27mm

• Exhaust Valve 25mm

• Valve Stem 5mm

• Combustion Chamber 20.9cc