[DeTomaso] Timing Your 351-C

JDeRyke at aol.com JDeRyke at aol.com
Tue Mar 13 04:00:51 EDT 2012


There were two different stock timing markers for 351-Cs; one was bigger 
but both fit and work similarly. Any untouched 351-C almost assuredly has a 
slipped harmonic balancer after 40+ years, which holds the mark you're trying 
to line up with your (missing) arrow. So that needs to be checked. You can 
adjust your timing with the old parts in place, but if the 4-lb outer ring on 
the balancer has moved a little (or a lot), it will continue and some have 
flown off, taking the belts with it. Others have worn holes in timing chain 
covers & oil pans so it bears inspecting.

As someone mentioned, the engine can be timed by ear (twist the distributor 
after loosening the hold-down clamp a little) since the marker only gives a 
number (using a timing light), and your engine does not care what it is; 
all it wants is a spark at the right time. I've timed 351-Cs by ear at race 
tracks and won events with the adjustments. It CAN be done!

For reference, '71s run well with about 10-12 degrees initial, 20-22 
degrees centrifugal, and 'some' from the vacuum advance to TOTAL no more than 34 
degrees. This is far less than Chevys need, by the way. The vac advance is 
set last and is adjustable with a 1/8" allen wrench stuck in the little pipe 
that mounts the rubber hose to the distributor. Set it so the engine does not 
rattle at any engine speed. Good luck- J Deryke


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