[DeTomaso] Initial Timming

Barry Seib oldwheel at mts.net
Thu Apr 30 15:45:51 EDT 2009


Daniel C Jones daniel.c.jones2 at gmail.com wrote:
Thu Apr 30 14:19:08 CDT 2009


Our previous dyno tests of a 10:1 compression 408 cubic inch Cleveland
with closed chamber iron heads made best power at only 32 degrees of
total timing.  The current 351C dyno engine made it's best power at 38
degrees.  However, some trace detonation was detected by the knock sensor
in the mid-range.  Rather than re-curving the distributor at that time,
we opted to pull the total timing back to 33 to 34 degrees.  We lost
around 5 HP but gained some safety margin.  We tested both engines through
the mufflers on 93 octane pump gas from the local Mobil station.
In general, open chamber heads need more advance than closed chamber.

YMMV,
Dan Jones


>>>Dan
Do you recall what the actual quench clearance was on either or both of
these engines?
I suspect ignition timing may be affected by changes in that.
Barry




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