Reply to "Help me choose a cam"

Congrats on your purchase, welcome to the family, and welcome again to the forum

Your use of english is great!

Here's my recommendation and other thoughts:

Cam: Crane Cams #529541 (grind HR-216/325-2S-12)
278°/286° advertised duration
216°/224° duration @ 0.050
Exhaust valve opens = 76° BBDC
58° overlap
Intake valve closing = 70° ABDC
0.562"/0.586" valve lift
112° lobe separation angle

This cam is advertised to be compatible with the compression ratio of your Pantera's motor. I would time it 4° advanced over Crane's recommendation. Opening the exhaust valve earlier will help the motor cope and perform better with whatever the back pressure of the exhaust system is, closing the intake valve earlier will help build dynamic compression, and the advanced timing will give the motor a little more low rpm snap when you accelerate off-idle. The duration at 0.050 and the intake valve lift aren't numerically impressive, but this cam is a sleeper.

Other stuff:

Crane (#36532-16) or Lunati (#72335-16) hydraulic roller lifters

PAC-1520 BBC beehive valve spring
(additionally nitrided version of PAC-1220 spring)

• 155 lbs. seated pressure
• 377 lbs./inch spring rate
• 0.650" maximum lift
• 1.88" installed height
• 1.445” OD – 1.00” ID

This is a Big Block Chevy beehive spring manufactured by PAC Racing Springs; the spring is sold by all of the major cam manufacturers under their own part number however. PAC Racing Springs is a small division of the Peterson American Company (i.e. PAC) the largest spring manufacturer in the USA. They manufacture the ovate wire beehive valve springs in two series, the 1200 series and the 1500 series. The 1200 series valve springs are the budget springs. The 1500 series valve springs are nitrided, polished and nano-peened; they are easily identified by their gold color. The 1500 series valve springs cost about 25% more than the 1200 series valve springs.

The installed height of the spring may require some spring pedestal machining or longer valves (more about that later).

Complimentary parts needed for this valve spring include steel valve spring cups (#PAC-C201) to securely locate the base of the spring and 10° spring retainers (#PAC-R310 chromoly or #PAC-R510 titanium) to properly hold the spring at the top.

The spring force at maximum lift shall be 367 lbs intake & 376 lbs exhaust. To use this cam and spring combination without machining the rocker arm pedestals for 7/16" fasteners is pushing the limits of the OEM 5/16" bolt that fastens the rocker arm to the pedestal. It should be OK, but there's not the usual amount of over-kill I like to build into a motor.

A roller rocker arm that doesn’t provide the ability to adjust the lifter pre-load is the Ford Racing Performance Parts bolt-down roller rocker arm #M-6564-C351. It is a good quality billet rocker arm that bolts directly to the OEM rocker pedestals via a 5/16” cap screw (it requires no head machining for installation).

A roller rocker arm that does provide the ability to adjust lifter pre-load is the Yella Terra YT-6015 roller rocker arm, another good choice that bolts directly to the OEM rocker pedestal (no machining is required). It is a billet aluminum rocker arm with a push rod cup style lash adjuster, which fastens to the pedestal by a 5/16” cap screw.

Since this camshaft is ground on a steel core you'll need to replace the distributor drive gear with a gear made out of compatible material.

Crane #52970-1 for 0.500” diameter distributor shafts
Crane #52971-1 or Ford Racing Performance Parts #M-12390-J, both for 0.531” diameter distributor shafts

Stiffer 5/16” OD pushrods – 0.120” wall thickness – manufactured to custom length

The length of the push rods need to be sized for your aplication and custom ordered. You won't be able to just pick a part number out of a catalog. The thick wall push rods as specified, having a 0.072” diameter by ~8.4” long passage down their middle, are effective at limiting the amount of oil flowing to the valve train in hydraulic tappet applications. The thick wall push rods also compliment the stiffer valve springs and allow the valve train to operate safely at higher rpm. One possible source for these push rods is Smith Brothers Push Rods of Bend Oregon, although it doesn't really matter to me where you buy them.

Even though you're installing a roller cam, the motor still needs oil with the anti-friction additive ZDDP in it, to properly lubricate the distributor gear and the mating gear on the camshaft.

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Please also be aware that sluggish performance may be the result of a poorly tuned or calibrated carburetor or a poorly tuned or calibrated ignition. The 351C is a fairly spirited performing motor, even in stock condition. It shouldn't "need" a roller cam to give it spirited performance. Certain Holley carburetors (like the 3310) are notorious for being poorly calibrated out-of-the-box.

It would be a shame to buy all these expensive camshaft parts only to find the motor still performs sluggisly, and that in reality all it needed was a good service and tuning!

Here's a universal ignition calibration for iron heads & flat top pistons:
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1. Set the distributor for 20° centrifugal advance. The centrifugal advance curve should start advancing a few hundred rpm above the motors idle rpm (assuming the motors idle will be set around 800 rpm +/- 200 rpm). The centrifugal advance curve shall advance 10° per 800 rpm to 10° per 1000 rpm. If the curve starts at about 1200 engine rpm it should end at 2800 to 3200 engine rpm
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2. Connect the vacuum advance canister to the carburetor’s ported vacuum connection. If the vacuum advance is adjustable it should be limited to about 10°
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3. Set the initial (static) advance at 16° to 18°
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4. With 16° to 18° of initial advance plus 20° centrifugal advance total advance equals 36° to 38°. The amount of advance at idle shall be 16° to 18° due to the initial advance setting, there is no vacuum advance at idle with ported vacuum.
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Finally, if the Pantera's motor is still equipped with the OEM valves, OEM connecting rod fasteners, and OEM crankshaft damper it is a ticking time bomb. The OEM valves are known to unpredictably drop their heads while the motor is running and perform catastrophic damage to the motor. The connecting rod nuts are known to pull their threads during spirited driving, also perfoming catastrophic damage. Due to the age of the rubber bond, the outer ring of the crankshaft damper is known to walk off the hub, and also slip and throw the balance of the motor off.

If you were to remove the cylinder heads to replace the valves, you could order 0.100" longer valves to help with the installed height of the PAC beehive valve springs.

Lots to think about.

Best Wishes

-G