305/350 Vortec PN 10241264
Intake Duration @ .050: 191
Exhaust Duration @ .050: 196
Intake Lift (w/1.5): 414
Exhaust Lift (w/1.5): 442
Intake Lift (w/1.6): 428
Exhaust Lift (w/1.6): 457
Lobe Separation: 111
These are my specs as of several years ago. 305 and 350 use the same cam.
these are the 1996 specs
96 L31 Camshaft Profile
Intake:
Opening Closing Duration
.004 14 BTDC .004 61.5 ABDC 255 Degrees
.050 13 ATDC .050 22.5 ABDC 190 Degrees
Inlet Centerline 106.25 Degrees
Max Lift .275 X 1.5 = .412
Exhaust:
.004 62 BBDC .004 24 ATDC 266 Degrees
.050 31.5 .050 16 BTDC 195 Degrees
Exhaust Centerline 115.75 degrees
Max Lift .281 X 1.5 = .423
Lobe Separation 111 Degrees
These are a little backwards. The 1.5 ratio doesnt work out to the 1.6 ratios listed.
I think they are mixed up a bit it should read.
intake lift with 1.5 rockers is .414
intake lift with 1.6 rockers is .442
exhaust lift with 1.5 rockers is .428
exhaust lift with 1.6 rockers is .457
these contrast with tyhe 1996 specs I found
96 L31 Camshaft Profile
Intake:
Opening Closing Duration
.004 14 BTDC .004 61.5 ABDC 255 Degrees
.050 13 ATDC .050 22.5 ABDC 190 Degrees
Inlet Centerline 106.25 Degrees
Max Lift .275 X 1.5 = .412
max lift .275 x 1.6 = .440
Exhaust:
.004 62 BBDC .004 24 ATDC 266 Degrees
.050 31.5 .050 16 BTDC 195 Degrees
Exhaust Centerline 115.75 degrees
Max Lift .281 X 1.5 = .423
maz lift .281 x 1.6 = ..450
Lobe Separation 111 Degrees
maybe these slight differences account for the 5 hp difference between the 1996 being 250 hp and the 1997-2002being 255 hpthus netting a 5 hp difference.
How knows?? Why are the Vortec camshaft specs so hard to come by? Is is a secret or something?
I would like to know the camshaft specs for the 295hp Vortec 350 marine engine , the 1 with the marine intake.
The marine engine and the L31 truck engine have the same heads and run the exact same 60 psi of fuel pressure, what makes the marine engine need the 24 lb/hr injectors and the L31 truck engine get by with the 19 lb/hr injectors??
I would love too know.
Paul
I ran into these specs on ebay, they say its out of a Vortec engine for marine use.
NEW 350 (5.7) CHEVY ROLLER CAMSHAFT
This (NOS) new roller camshaft is out of the vortec engine made for marine applications. It comes with the fuel pump lobe so that it can be used for the fuel injected or carburated applications. This is a new take out camshaft. GM part# 14097395. Specs are a little better than normal Gm stock roller cams.
CAMSHAFT SPECS:
Lift Int .431 Exh .452
Duration 196 Int. 206 Exh @.150 Tappet lift
Centerline 108 degree ATDC Int. 115 degree BTDC Exh.
I just checked in my GMPP books and these exact specs are from the cams used in the 350 hp Ramjet 350, the RJ 350 uses the LT4 rollerrockers.
350hp@5200 rpm
400 lb/ft torque at 3500
this same cam is also used in the HT 383 engine
325hp@4500rpm
415 lb/ft torque @ 3500rpm
Do you guys think that this is what the Marine intakes used to get 295 hp from the Marine 5.7 and 320hp from the Marine 6.2L Chev V8's?
I think it is.
pauly
his is the the same one in the HT 383 I'm looking at!!!!
14097395 Hydraulic Roller Design
This hydraulic roller design is used on the 383 truck. The duration at lash point in degrees (intake/exhaust) is 288/308; duration at .050" tappet lift (intake/exhaust) is 196/206; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 431/451. Valve lash is zero/zero and lobe centerline is 109 degrees.