My build

[96 century]

This is what I have planed for my 97 3400. What do you guys think?

Stock bottom end with .75mm over pistons.

Mild reground cam
specs form this site, 206º intake / 210º exhaust (@ 0.050" lift) and a lobe lift around 0.295"
I shouldn’t need custom push rods correct?
Will stock lifters work fine?

Heads
P&P any hints or suggestions. I’ve ported heads before just not 660 heads.
Milled .010
Valve job
Ls1 or Ls6 springs, LS1 seats, Gen 2 valve seals. < Why can’t I use gen3 valve seals?

Intake and Exhaust Manifolds
P&P any hints or suggestions here

Performance exhaust

FFP pulley

I know there will be a lot to be gained in tuning the computer. Will it run ok on the stock tune for my 96 3100 until I get a tuner?

3100 injectors seem to be what you guys are running? What is the advantage over running 3400 injectors?

Dose this look ok? Thanks in advance! ~Josh

[geoffinbc]

Fuck that FFP pulley... A little more cam.

Maybe 210~216* intake and 216~230 exhaust. Get the lift up to 0.500 (312 lobe)

LS6 springs or jump right to the COMP springs

[96 century]

Alright sounds good

[AaronGTR]

Re: My build

specs from this site, 206º intake / 210º exhaust (@ 0.050" lift) and a lobe lift around 0.295"
I shouldn’t need custom push rods correct?
Will stock lifters work fine?

I'd also say go higher on the lift. Stock lobe lift is .2727" so you aren't much higher than that. Say a .31" would give you .496" valve lift. Go with that or a little higher. Stock pushrods and lifters will be fine.

Ls1 or Ls6 springs, LS1 seats, Gen 2 valve seals. < Why can’t I use gen3 valve seals?

LS1 springs aren't stiff enough for anything more than a stock cam. Go with LS6 or comp springs like Sappy said. You can't use gen3 seals because they are one piece with the spring shim and LSx springs won't fit over them. The gen2 seals are seperate so you can use them with the LS1 shims.

Intake and Exhaust Manifolds
P&P any hints or suggestions here

Just port matching to the gaskets is most important there IMO. And porting the upper intake opening if you're using a larger TB, which I also recommend. Wouldn't bother doing anything with exhaust mani's though. It won't help because they are extremely restrictive. It's headers or nothing IMO.

I know there will be a lot to be gained in tuning the computer. Will it run ok on the stock tune for my 96 3100 until I get a tuner? 3100 injectors seem to be what you guys are running? What is the advantage over running 3400 injectors?

It will probably run but not very well on a stock program. Not with a cam and all that porting work and extra displacement from boring. You'll probably run lean as hell. I'd get bigger injectors and you'll need a DHP powrtuner to make them work. It will work with your pcm. As for injectors, the 3400's are bigger than 3100's so I don't know why anyone would run 3100's over 3400's. The 2000+ 3400's injectors where rated at 22.5lb/hr @ 55psi. You can also get 28lb/hr injector from the 4.2L inline six in the envoy/trailblazer that will fit. Hope that helps.

[96 century]

It will probably run but not very well on a stock program. Not with a cam and all that porting work and extra displacement from boring. You'll probably run lean as hell.

really?? wont the O2S and the MAF see the need for more A/F and cmpensate?

if you're using a larger TB, which I also recommend.

What are my choices on trottle bodies. I'd love to have a billet one from the store on this site but money wont allow. What are my other options?

[AaronGTR]

The O2 sensor and MAF can only respond so fast and adjust so much. At part throttle though you're right, they would probably adjust, so at cruising speeds you'd probably be ok. It wouldn't want to idle well though until you increased the idle speed, and at WOT it would probably still be lean since it doesn't use the O2 for fueling under those conditions, and the injectors would probably be maxed anyway. So basically you'd be better off not stomping the gas down until you get a tuner, but you could certainly drive it.

TB, basically you have the one here, and the bored RSM which is actually a little more expensive. I guess if the money's not there it can wait of course. It would be a nice mod to add in the future though.

[96 century]

The O2 sensor and MAF can only respond so fast and adjust so much. At part throttle though you're right, they would probably adjust, so at cruising speeds you'd probably be ok. It wouldn't want to idle well though until you increased the idle speed, and at WOT it would probably still be lean since it doesn't use the O2 for fueling under those conditions, and the injectors would probably be maxed anyway. So basically you'd be better off not stomping the gas down until you get a tuner, but you could certainly drive it.

So whats causes this problem? The extra displacement? The extra air flow? The cam?

[AaronGTR]

Not sure what you're asking. You mean what causes it to run lean? Well obviously any time you put more air in the cylinder the computer has to try and add fuel to compensate but there is a limit to what it can do with the stock programing and the stock fuel system. There are a few people with cams now that have found it necessary to get slightly bigger injectors because they were on the edge of maxing out the stock ones. If you have a cam, more displacement, everything ported etc, you are pulling a significantly larger amount of air into the cylinder. Any time you change something that significantly from the factory setup, the computer should really be programmed along with it.