265 (4.3L)-287-301 (4.9L)-316-326-347-350370-389-400 (6.6L)-421-428-455 cu.in.
Pontiac V-8 55-81
COMPLETE CAM SPECIFICATIONS Application
RPM Camshaft POWER PART NUMBER/ RANGE Emissions Code
Camshaft Series/ Grind Number
Mechanical Lifter Camshafts Replacement for factory 389-421 Super Duty McKellar no. 10
BluePrinted 541596
26006400
280901
See pg. 273
LIFTERS
Degrees Advertised Open/Close Lash Gross Duration Degrees Degrees @ .050” Hot Lift @ .050” Duration Lobe Cam Lift Int. Int. Int/Exh. Int/Exh. Separation Int/Exh Exh. Exh.
99255-16c
236 247
268 284
113.5
2 54 54.5 12.5
.012 .416 .018 .420
99255-16c
244 252
280 288
106
19 45 55 17
.026 .518 .026 .536
99255-16c
248 258
290 300
112
17 51 66 12
.022 .500 .022 .520
99255-16c
252 260
288 296
106
23 49 59 21
.026 .536 .026 .554
99255-16c
260 268
296 304
108
25 55 65 23
.026 .554 .026 .572
28570-16d
228 236
278 286
112
7 41 55 1
.020 .507 .020 .525
28570-16d
236 244
286 294
112
11 45 59 5
.020 .525 .020 .543
28570-16d
244 252
294 302
112
15 49 63 9
.020 .543 .020 .561
28570-16d
252 256
302 306
112
19 53 65 11
.020 .561 .020 .561
28570-16d
268 276
300 308
110
28 60 72 24
.020 .630 .020 .630
1
CAMSHAFTS
Good low end and mid range torque and HP, rough idle, F-244/3454-2S-6 moderate performance usage, limited oval track, bracket racing, auto trans w/2500+ converter, 10.5 to 12.0 compression ratio advised.
30007000
Good mid range torque and HP, fair idle, moderate performance usage, mild bracket racing, auto trans w/2500+ converter, good w/plate nitrous, 10.0 to 11.5 compression ratio advised.
F-248/3334-2-12
34007000
Good mid range torque and HP, rough idle, performance usage, short oval track, bracket racing, auto trans w/3000+ converter, 11.5 to 12.5 compression ratio advised.
F-252/3574-2S1-6
Good mid range and upper RPM torque and HP, rough idle, performance usage, bracket racing, auto trans w/3500+ converter, 12.0 minimum compression ratio advised.
F-260/3694-2S-8
3
36007400
280981* 3
40007600
281441* 3
SR-228/338-2S-12 IG
22006200 26006600
Good mid to upper RPM torque and HP, fair idle, moder- SR-244/362-2S-12 IG ate performance usage, mild bracket racing, auto trans w/3000+ converter, good w/plate nitrous, 3800-4200 cruise RPM, best with 421+ cu.in., 10.5 to 12.0 compression ratio advised. Good upper RPM torque and HP, rough idle, moderate SR-252/374-2S-12 IG performance usage, bracket racing, auto trans w/3500+ converter, good w/plate nitrous, 4000-4400 cruise RPM, best with 455+ cu.in. with aluminum heads, 11.0 minimum compression ratio advised. Competition only, good mid to upper RPM torque and HP, R-268/420-2S-10 bracket racing, auto trans w/race converter, good w/ manifold nitrous, best w/455+ cu.in. with aluminum heads, 12.0 minimum compression ratio advised.
30007000
RPM range shown is for average usage. These cam profiles will RPM higher, depending upon application. IMPORTANT: Adjustable Vacuum Advance Kit available. See page 313 for details.
288541*a 3
Good low end and mid range torque and HP, fair idle, SR-236/350-2S-12 IG moderate performance usage, mild bracket racing, auto trans w/2500+ converter, good w/plate nitrous, 34003800 cruise RPM, 10.0 to 11.5 compression ratio advised.
260
281241* 3
Mechanical Roller Camshafts Excellent low end torque and HP, good idle, daily performance usage, mild bracket racing, 3000-3400 cruise RPM, 10.0 to 11.5 compression ratio advised.
280921*
288551*a 3 288521*a 3
34007200
288531*a 3
42007800
288811*b 3
NOTE: In order to effect valve adjustment when using mechanical lifter and roller lifter camshafts, a set of positive locking nuts, such as 99768-16, must be obtained for the rocker arm studs. NOTE: Specify if casting number 540306, 544127, or 9771980 heads with 1.65 ratio rocker arms are being used.
CRANECAMS.COM
NOTE: Be sure to maintain at least .040” clearance between the underside of the rocker arm and valve spring retainer when the valve is closed. Since 1975 General Motors divisions have exchanged engines throughout different models. Be certain of exactly which engine you have before ordering.