TBI Vortec head swap , question

[bacon310]

So I decided to go with a vortec head swap because it seems easier than dropping a 383 into my CA truck. So I got the GMPP tbi vortec intake manifold and a set of vortec heads. My question is do I need to get a new cam or will the stock cam work? And if I do have to replace the cam what would be best to get some horsepower gains without going to extreme to where I wouldn't be able to pass smog. I don't plan on doing anything crazy to the engine other than the vortec head swap, its going to be daily driver with some light 4 wheeling from time to time. Any help would be great.

 

[dyeager535]

You got all the EGR components? I don't know if I still have my components or not, but it's a hassle to run. just figured I'd put that out there first if you haven't considered that, knowing how tough CA emissions are or can be. No visual inspection?

You'll need to have the ECM reprogrammed no matter what you do, what is your goal with the truck? Really need to determine what you want out of the truck before you pick a cam. Small cam makes more torque than a larger cam, the Vortec cams are pretty small for this, and they work well for low RPM operation and getting the truck moving. If looking for upper end power, going to want a larger cam. Need to pick the cam before you have the ECM reprogrammed.

 

[bacon310]

I want it to be as efficient as possible. its going to be my daily driver and some light 4x4 stuff when I go hunting into the desert. I don't plan on doing anything to wild with it. I was reading that a ECM reprogramming wasn't necessary. I have the egr components, they're still in the truck I haven't pulled the motor yet. I wanted to make sure I had everything I needed before I pulled it.

 

[Bent77]

The vortec heads seem to have issues with increasing the lift on the cam

 

[dyeager535]

The ECM needs reprogrammed. Instead of re-typing, you can read my comments here: https://ck5.com/forums/threads/5-7-vortec-swap-guide.330752/

IME I was able to run .454" lift on the Vortec springs and just barely clear. I can tell you that in terms of the butt dyno, the aftermarket cam with more lift didn't make noticeably more power than the pretty anemic factory Vortec cam. Even though the aftermarket cam I ran was pretty mild compared to what all is possible, it does feel like low end torque is improved with the Vortec cam.

Here is what it looked like last time I took the truck out. This is part of the datalog of my crate L31. Running on the tune from the previous 350 I had in it, with Vortec heads, in the same truck, same induction, but previous engine had a more aggressive cam. The red is for my own emphasis as I look at the data:



Knock count is 112 (and climbing, that is in the middle of the datalog), and it's pulling up to 5* of timing (not shown in that segment) simply due to knock. Not once did it audibly ping. So I put zero credence into anyone saying you can make major changes like heads, cam, and/or intake and have it "run fine", without showing the datalog(s) to prove it.

That same tune, on the previous engine, had 11 knock counts in 45 minutes of datalogging. The picture above is less than 10 minutes of run time.