351-C Cam Data

To see what you can make from a 351-C 2V, look at a comparison of stock cams for the 351-C 2V & 4V, 351W 2V & 4V, Boss 302, Boss 351, and other high performance 351 engines for various years. Then you can see how easy it is to boost the 351-C 2V. The top line of specs is for when the cam first starts to move the valve. The second line is for 0.050" lift, which is commonly used by cam manufacturers.
 

Typical Cam Profiles
Year  Engine Type Intake:
First open & 0.050" Cam Lift
Exhaust:
First open & 0.050" Cam Lift
Over-
lap
Open Close Dur. Lift
(in.)
Open Close Dur. Lift,
(in.)
65-68
68-72
289
302
Hyd. 16° BTDC
40° ATDC
70° ABDC
8° ABDC
266°
148°
0.360 44° BBDC
1° BBDC
20° ATDC
27° BTDC
244°
154°
0.380 36°
63-69 289
Hi-Perf
Mec. 46° BTDC
12° ATDC
84° ABDC
26° ABDC
310°
194°
0.480 94° BBDC
36° BBDC
36° ATDC
22° BTDC
310°
194°
0.480 82°
67-68 302 Mec. 52° BTDC
6° BTDC
86° ABDC
30° ABDC
318°
216°
0.510 82° BBDC
40° BBDC
42° ATDC
4° BTDC
304°
216°
0.510 94°
69-72 302 Hyd. 36° BTDC
16° ATDC
74° ABDC
20° ABDC
290°
184°
0.470 84° BBDC
32° BBDC
26° ATDC
28° BTDC
290°
184°
0.470 62°
69-70 302
BOSS
Mec. 34° BTDC
15° ATDC
76° ABDC
25° ABDC
290°
190°
0.477 86° BBDC
47° BBDC
24° ATDC
27° BTDC
290°
200°
0.477 58°
Opt. 302
BOSS
Mec. 58° BTDC
12° BTDC
86° ABDC
32° ABDC
324°
224°
0.598 88° BBDC
42° BBDC
56° ATDC
2° ATDC
324°
224°
0.598 114°
69-71 351W Hyd. 11° BTDC
34° ATDC
65° ABDC
15° ABDC
256°
161°
0.425 68° BBDC
15° BBDC
22° ATDC
33° BTDC
270°
162°
0.450 33°
Opt. 302 Mec. 66° BTDC
20° ATDC
84° ABDC
33° ABDC
330°
233°
0.600 94° BBDC
47° BBDC
64° ATDC
11° ATDC
338°
238°
0.620 130°
70-74 351C
2V
Hyd. 12° BTDC
38° ATDC
66° ABDC
11° ABDC
258°
153°
0.400 66° BBDC
11° BBDC
20° ATDC
37° BTDC
266°
154°
0.406 32°
70-71 351C
4V
Hyd. 18° BTDC
35° ATDC
70° ABDC
14° ABDC
268°
159°
0.420 81° BBDC
26° BBDC
19°ATDC
36° BTDC
280°
170°
0.450 37°
71 351C
CJ
Hyd. 18° BTDC
30° ATDC
72° ABDC
22° ABDC
270°
172°
0.481 82° BBDC
28° BBDC
28° ATDC
24° BTDC
290°
184°
0.490 46°
72 351C
CJ
Hyd. 14° BTDC
26° ATDC
76° ABDC
26° ABDC
270°
180°
0.481 78° BBDC
24° BBDC
32° ATDC
28° BTDC
290°
176°
0.490 46°
71 351C
BOSS
Mec. 34° BTDC
15° ATDC
76° ABDC
25° ABDC
290°
190°
0.477 86° BBDC
47° BBDC
24° ATDC
27° BTDC
290°
200°
0.477 58°
72 351C
HO
Mec. 17.5°BTDC
23° ATDC
77.5°ABDC
40° ABDC
275°
206°
0.490 17.5°BBDC
37° BBDC
77.5°ATDC
20° BTDC
275°
197°
0.490 35°
Opt. 351C
HO
Mec. 62° BTDC
18° ATDC
84° ABDC
35° ABDC
326°
197°
0.589 90° BBDC
45° BBDC
64° ATDC
13° BTDC
334°
212°
0.612 126°
71-72 400C Hyd. 17° BTDC
30° ATDC
59° ABDC
8° ABDC
256°
158°
0.422 71° BBDC
37° BBDC
21° ATDC
37° BTDC
272°
180°
0.427 38°

You can see that the 351-C 2V cam is rather mild in that the duration is low (Intake=258° & Exhaust=266°) as compared to the 351-C CJ (I=270° & E=290°) or the 351-C High Output (I=275° & E=275°) hydraulic cams. Note that the only difference between the '71 and '72 CJ cams is a 4 degrees, achieved through a different cam timing gear setting. The cams are exactly the same profile. Also, note that the stock 2V cam has only 0.400" lift.

Calculating Duration:
Intake Duration = Degrees before TDC + Degrees after BDC + 180. In the case of the stock 351C-2V, the duration is 12+66+180=258.
Exhaust Duration = Degrees before BDC + Degrees after TDC + 180. In this case it is 66+20+180=266.

Since the exhaust valve opens before the intake valve is closed, both valves are open at the same time. The exhaust actually helps scavenge the cylinder and suck gas in through the intake. This allows unburned gas to go out the exhaust, but it gets a larger amount of new gas into the cylinder more quickly. So this overlap can increase power, but is terrible for mileage.

The timings in the chart below are based on the position of the crank (degrees of rotation) when the valve first starts to open. An alternative is to specify the cam based on when the valve has opened 0.050 inches. This is often a better method and is frequently used by the cam manufacturers. You will see from the table above, the specifications can appear to change significantly using this alternative method. Click on chart to enlarge it.