I just replaced the motor in my 78 4x4 with a 400 mod from a 1 ton camper special and thinking I'd do the gears and timing chain before putting it in ,discovered the timing gear on the crank has 3 keyways T D C 40o - &
40o + engine is timed at -40 for some weird cam ford put in in the last year of prod. in 82 but ford cant tell me anything as usual as the motor is older than most of thier employees.anybody know anything more about this beast than I've found out so for?
What you have is an aftermarket crank sprocket with -4 - 0 -
+4 deg settings. Originally, the Ford sprocket was unmarked but, had the cam retarded 7 deg for emissions reasons which thoroughly killed any performance and fuel economy. Whoever replaced it before used the right setup but, should have set it at "0" for straight up cam timing. If it were mine, and, the cam is not an aftermarket cam with a ground in advance, I would set if at +4 deg to give better bottom end response. If you are not sure of the cam, set it at "0". Some aftermarket cams have a 5 deg advance ground in which would be too much with +4 dialed in at the sprocket.
Lastly, it is not a 400 mod unless you have modded it. The "M" designation was for the 351M only to distinguish it from the other 351 in the 335 series engine family. The 351M is a destroked 400 built to replace the 351C which was discontinued after 1974. Since they were visually very close in appearance and basically the same vehicle applications, the M was used to ID the replacement engine. The 400 was just a 400 and, did not need a separate ID as it is the only 400 CID engine series Ford ever built. It never even had a 4V carb option from the factory.
That's 4 degrees + or -, not 40. There are no weird Ford cams, however, manufacturers, Ford included, were retarding cam timing to help out with emmisions in the 1970s. No big deal. Actual cam timing data is found in the factory repair manuals. Lugnut has suggested advancing the cam timing, something that may help move the powerband down a few hundred RPM. I do that as well on mild apps.
So, what are you asking? Do you want to know if this is OK or not? Are you looking for some suggestions as to parts? Do you know if the cam is stock?
A cool web forum for trucks and 400s is found here:
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