[DeTomaso] Timing Your 351-C

Sean Korb spkorb at gmail.com
Tue Mar 13 08:00:30 EDT 2012


What Jack said.

In the '40s and '50s (not that I remember them, just have some old
tech manuals) home maintenance was common and using a vacuum gauge was
advised.  Set the timing until you get the highest steady vacuum  with
the vacuum advance disconnected (the 351C in a Pantera is a little
lumpy, but you can find it).  In practice I found that retarded timing
makes the idle rougher and more advanced timing is smooth for quite a
large range (10 or more degrees).  Back it up to where you first found
the best vacuum (the retarded side of the smooth range), set it and
reattach the vacuum advance if desired.  That should be advanced
enough to drive without overheating,and retarded enough to start the
car when warm.

But ummm... you really need to find TDC on the car and put a mark on
your balancer.  I had a distributor pin shear off and the shaft was
tight enough for the motor to operate, but the timing kept slipping.
The only way I found this was looking at the marks I made on the
balancer with a timing light (my balancer hadn't slipped, but you have
to be sure) to watch the centrifugal advance operate.  It was most
peculiar watching the marks drift away from my sight after revving the
motor a bit.

sean

On Tue, Mar 13, 2012 at 4:00 AM,  <JDeRyke at aol.com> wrote:
> 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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-- 
Sean Korb spkorb at spkorb.org http://www.spkorb.org
'65,'68 Mustangs,'68 Cougar,'78 R100/7,'60 Metro,'59 A35,'71 Pantera #1382
"The more you drive, the less intelligent you get" --Miller
"Computers are useless.  They can only give you answers." -P. Picasso



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