1991 Formula Dyno Diagnosis Engine
Changing the valvesprings with the heads still attached to the engine and the engine in the car isn't a whole lot of fun, but it can be done. It takes an air-hose fitting that fits in the spark-plug hole to pump compressed air into the cylinder so the valves stay in place when the retainers are removed. We used one from a leakdown kit. You'll also need the special "on-car" valvespring compressor; we got ours from Comp Cams.