Cam for Vortec 350

d57gmcbell · January 14, 2005

I am doing an engine swap. And I was wanting to know if anyone knew the cam specs for a stock vortec 350. Also how big can you go and still keep the the fuel injection running correctly...... thanks

Marty46127 · January 20, 2005

I have some of the stock cam specs for my 1998 L31 (350), these come straight out of the GM Factory Manual

1) Exhaust Lift = .4305 (.287 Lobe lift x 1.5 Rocker Ratio)

2) Intake Lift = .417 (.278 Lobe Lift x 1.5 Rocker Ratio)

I do not have duration or centerline specs, though I am sure htey are mild.

Regarding you question of "how big you can go", the answer is more complex and dependent upon:

1) What is your intended use for the engine? Street? Towing? 4 Wheeling? As the cam grind becomes more aggressive you may lose low RPM driveability and idle quality

2) Are your cylinder heads Vortec stock? This is a lift limitation with stock stamped steel rockers (may need to replace rockers with long slot or roller variety) Same is true with valve springs.

That said, just did (last summer) an L31 Vortec build on my 1998 K3500:

1) GM Goodwrench stock 4 bolt replacement short block

2) Comp Cams custom ground hydraulic roller cam shaft (spec'd by Comp cams based on my daily driver & horse trailering needs):

Intake = .459 Lift 257 duration @ .006 tappet lift

Exhaust = .457 Lift 262 duration @.006 tappet lift

112 degree lobe separation, installed to 108 degree centerline

If you are interested, grind# = CS 3302/3300 HR112.0

3) Comp Cams Hi-Tech Roller timing chain

4) Stock GM Vortec '906 cylinder heads with Comp Cams 1.52 Pro Magnum roller rockers (required taller valve covers and modification to the A/C compressor mounting bracket)

5) Banks PowerPack (Headers, SS exhaust, K&N Air filter)

6) MSD 6A Ignition w/MSD Coil

7) Stock Vortec EFI Manifold & Injector Setup

8) Stock ECM calibration (for now )

What a difference from stock!! HUGE mid-range torque increase, definately stronger on the bottom and very top end. The only issue that is cam related is an idle that is a bit "lumpy" and slightly wandering (hope to make that go away with the PCMforLess treatment). Gut tells me that significant gains can be had with good custom PCM tweeking. Not sure if the CPSI injection will be able to keep up without a fuel pressure increase.... We'll see.

So long answer to your short question, stock setup works just fiine for the cam specs I upgraded to above.

-Marty

I am doing an engine swap. And I was wanting to know if anyone knew the cam specs for a stock vortec 350. Also how big can you go and still keep the the fuel injection running correctly...... thanks

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