Not so Hot -Reply

[Daniel Jones <djones2@mdc.com>]

>351C 4 barrel closed chamber heads from 1970 Torino.
>Rebuilt with flat top pistons and a 280 Crane Cam
>9.5 compression, 93 octane gas.(slight ping under load)

Compression with closed chamber heads and flat tops should
be around 10.5:1.  Should not ping with the quench heads and
a proper curve in the distributor.  Open and closed chamber 
heads require different spark curves with the closed chamber,
heads requiring less total advance (32 to 36 degrees total).

Dan Jones