Actually, I would get a set of 4.56 or 4.88's if you want more power.
I have a 268 cam and It was deffinatly worth it.
I got the whole kit from comp cams and put it in myself.
New valvesprings, retaners, seals, locks,timing chan... etc
I also had my heads ported at the same time.

 

Dealing from experience, don't go edelbrock or crane, go with comp cams. I wouldn't go with a chip either, some people bull [censored] you into a chip, but all it does is richen up the fuel and reset the base timing curve (all things you can do yourself) For the cam specs, I would go with not much more than 200 Duration @0.5 and 490 lift this will give you plenty of low end and the best way to adjust the timing is to advance the base curve as far as you can, but not to far to get spark knock. And get an adjustable regulator and O2 reader and adjust the fuel on a dyno while reading the exhaust under various throttle conditions. Basically tune it to the max

 

yeah, you should regear depending on the size tire you're running.

if a shop installs a lift and bigger tires, shouldn't they suggest a gear change?

 

Just to get a little off subject. Do you have any pics you can post? I love seeing lifted Tahoes, It gives me inspiration.

 

you got some good advice, but keep this in mind - ODB2 requires reprogramming the computer for the new cam specs - and you cannot adjust the timing manually on ODB2 system, it is completely controlled by the ECM. Same with re-gearing - you'll need to reprogram the computer for the new gear ratios (if you get new gears) - and I may be wrong, but the ECM only supports up to a 4.1 gear ratio (can anyone confirm?). As far as tires, the ECM can only be reprogrammed to 32 inch tires (again, I may be wrong, my memory doesn't serve me to well).

I'm curious: What intake mod did you do? Ramair (or FIPKit, whatever) or did you swap in a new intake manifold?

 

yeah, don't they have a power programer for them?? That does everything

 

Undertow, I've heard the same thing - but I understood it differently. I thought that those were "stray" (don't know the technical term) limits. Lets use your numbers for example because I don't know for sure either. I thought that meant that with stock gearing your tire size can only stray from stock up to 32" - or 4.1 gears and factory tires and the computer still be happy. But I figured that meant that you could put 38's and 4.88's in because it's still within the same thresh hold because you've upped the numbers on the tires and gears perportionally. Now the ABS factor I don't know about, I've been told that it won't really hurt it because the sensors are looking for lockup. I'd imagine that means that weather you have 6' or 6" tires the ABS sensors/system won't allow the tire to lockup so it will still work, however as always taller tires means less stopping power. I don't know, that is just what I've read/heard.

 

pfunk, the HPP3's are somewhat limited - sure they can make certain changes (ratio, shift points, whatever), but there is no way a $300 programmer will let you change the ECM's cam specs. The programmers are great, and I would buy one if my buddy didn't let me use his tech2 at work - but once I get my cam, gears, tires (and maybe a blower...hehehe) I'll have the ECM reprogrammed by a pro.

rebel - VERY interesting point. Personally, I was under the impression that the variables in ECM had min and max values pre-defined. Assuming you are correct, and those values are REALATIVE to factory settings (not static), then us guys with ODB2 are free and clear to upgrade anythign we want (keeping my fingers crossed!)!!! Definately worth looking into. thx for the insight.

 

what are yall talking about the ecm and ODB2 what is all of this stuff? are yall saying that the computer is programmed to only turn 32's max without problems and if i get bigger then i have to take it to someone to reprogram my comuter. and also what will changing the camshafts do is it worth the money what kind of change will it make?

 

All modern vehicles ae controlled by a computer. The systems and components that monitor and adjust how your vehicle runs is called On Board Diagnstics (OBD) - OBD2 is the 2nd generation of these systems.

The ECU/ECM is the "main-brain" (Electronic Control Module/Unit) that stores alot of the variables that are critical to performance of your vhicle.

All we're saying is that if you own a truck with OBD2, it is not quite as cut and dry when doing upgrades. Things like tires size, gear ratio, air/fuel ratio, cam specs are all stored by the computer (ECM) and would need to be changed to reflect any mods you do. Between Rebel and myself, we are unsure about the MAX supported tire size/gear ratio/whatever, but I am looking into it.

You can buy a whole boatload of different cams to achieve different things - its a worth while mod if done correctly.

 

If you find a dealer (or tuner) that knows what he's doing, reprogramming the computer for tires outside of that range is entirely possible- there are several ways to do it. THere are some transfer functions that can be modified to correct it.

About ABS...my one roommate is an ABS engineer for Bosch, and his direct advice is to pull the ABS fuse as soon as you put bigger tires on the vehicle. If you increse diameter and rotating inertia, it gets all kinds of f'd up! And there's a serious potential to underbrake the vehicle in certain scenarios (like driving down a slippery hill). It still works fine for the most part, but your stopping distances increase...and that's not cool.

About the cam...I wouldn't even bother unless you do a fair amount of head work. You won't see much if any gains if you only upgrade the cam and nothing else- it will want to flow more air than the heads can support.

There's always a Whipplecharger....

 

In reagrds to the 96-98 5.7 vortec motors...You already have the best flowing factory head on the truck. It's not gonna get much better. Look @ SDPC's web site, or in their catalog, shows the figures for flow. You guys also have roller cams. Crower makes the best, then Comp. Don't stray too far from a 114 lobe centerline, and no more than .500 lift. Keep in mind, your going to have change the springs any how. Leave the rockers alone, going to a 1.6 ratio will change the geometry of the pushrod enough to start wearing on the valve guides and seals...I learned the hard way, after going through 2 sets of seals over 50k miles. Also, slap some nice headers on it, it will help out the cam. My personal fav is JBA. Nickel plated, 3/8" flange, I have never heard of them leaking.