This is in reference to my 455HO Firebird thread:
https://www.yenko.net/ubbthreads/ubbt...eux#Post503488
I just warmed the car up and did a compression check. (Throttle propped at WOT, all plugs out, cranked 7 revolutions for each cylinder- gauge stopped climbing at 6 revolutions).
I would say the cylinder pressure is just a little bit high for an 8.4 to 1 compression engine?
Cyl 1: 230 psi
Cyl 2: 220 psi
Cyl 3: 225 psi
Cyl 4: 230 psi
Cyl 5: 227 psi
Cyl 6: 230 psi
Cyl 7: 220 psi
Cyl 8: 235 psi
For you engine gurus out there, would that confirm that the camshaft in this thing is WAY WRONG for this application? It does have stock looking flat top pistons, as I can see the valve reliefs through the spark plug hole (no dome). The car pings at just about any timing setting. Even on 100 octane low lead avgas mixed with 93 unleaded.
I guess this could also be the cause of the oil leaking past the main seal under full throttle. A whole lot of overpressure down there.