ZZ4 cammed vortec is a slug

[SparKnocK]

I got a 98 xcsb 4x4 sierra that used to be a 305 vortec but i blew that up so i bought a vortec 350 long block, zz4 cam, ls6 springs, 787 retainers, updated spider, wait for me tune, and a 2500 stall. The engine has about 1000 miles on it since the build but the truck is really sluggish, gets about 11 mpg and idles rough kind of like a misfire but its not throwing any codes. The lifters are also still noisy after adjusting them a couple times at 1/2 and 3/4 turns. The exhaust and intake are stock right now and it has 3.42 gears but i still figured the truck would get up and go better than it does with the upgrades it has.

Man i hope i can figure this out soon cause i was hoping for a tire burnin SOB so if anyone has any tips or suggestions i would really appreciate it. Thanks

[SimpleGreen]

IMO, the tuning may need more work.

I had a Vortec 350 with a ZZ4 cam in my 1993 step side. It had a Holley 600 carb on it. Pulled 367HP/425TQ at the flywheel on the dyno.

I pulled it out and sold it to my buddy. His is identical to mine but its a 1998 Vortec truck. Otherwise it has the exact same gears, transmission, tire size, and lowering kit. It runs alright with his Vortec setup, but not great. The local turners charge $200 more than usual to tune the Vortec CMPFI motors because the timing is difficult to make work correctly (according to them).

That being said, I now have a stock 285HP 5.3L V8 in that same 1993 step side. I'll run door to door with him until 80-90 and then I start to edge away slightly. Kinda funny because I'm outrunning the old motor I paid so much to have built with a stocker from an '02 Silverado.

[SparKnocK]

Ya those ls motor are beasts, thanks for the input i hope i dont have to chase this thing around forever or its goin on craigslist

[brutal]

my old zz4 cam pulled pretty hard. look up my youtube vid, vortec 355 0-100 run :read:

[6789olds]

could be the tune , or maybe the cam was installed wrong and its off some degree's how does the top end pull ?

[SparKnocK]

Starts giving up around 5000 rpms midrange is decent but the throttle response and low end are lazy as hell.

[Jameslleary]

sounds like the cam may be advanced a bit.

[SparKnocK]

Everything lined up perfect on the the timing part of it all had a little trouble scanning the truck but i figured it has to be close with it not throwing codes. Has anyone had any problems with timing even though its not setting a check engine light? Thanks

[Jameslleary]

I vote for the Tune. Maybe larger injectors.....do you have an AFPR?

[The Fiddle]

I vote for the Tune. Maybe larger injectors.....do you have an AFPR?

Larger injectors are not possible with the stock Vortec 305/350 intake.

OP: I noticed you said your exhaust is still stock. With ANYTHING over stock the stock Vortec 350 exhaust is THE choking point of the potential of the engine. Tri-Y or LT headers and a full 2.5" dual system will help the engine tremendously. Next is the tune. It is entirely possible the tune is off or that your particular setup needs attention beyond a mail order service. A street or dyno tune would also pinpoint any abnormalities or restrictions you are facing.

That being said I know for a fact my Vortec 383 is being held back by the stock exhaust manifolds/headpipes/cats and that the tune also needs adjustment. I faced the same thing you are facing now.

[SparKnocK]

My plans are to open the exhaust up and get it back on the tech 2 to do some more tweakin first then deal with the nightmare tuning process. I would like to keep the stock manifolds with true duels and try larger downpipes too. Has anyone had any luck with that type of an exhaust setup? Thanks

[The Fiddle]

The headpipes on the 3/4 ton GMT400 trucks is a larger and better flowing 2.75" IIRC. It would help, but the manifolds are still very restrictive.

[brutal]

:word: manifolds should be the 1st thing that is upgraded

[haulinit]

I have a zz4 cam in my and it runs pretty good. Yes the valve noise is rather loud, I'm running full roller rockers it bugs me but have come to live with it. The tuning is a pain in the a** I'm slowly working on mine. Not to knock w4m but I would have went with a premium tuner. I had a Wheatley 93 tune on my black box before I went to a 411 so I could use my EFILive on my truck. The tuning maybe off. It could be the timing after you stabbed the dizzy did you adjust the timing with a scanner to +\_ 2 degrees from zero with the Rpms above 1200? My truck was a super slug until I adjusted it. It did not throw a code and it was retarded 10 degrees.

[Jameslleary]

Larger injectors are not possible with the stock Vortec 305/350 intake.

OP: I noticed you said your exhaust is still stock. With ANYTHING over stock the stock Vortec 350 exhaust is THE choking point of the potential of the engine. Tri-Y or LT headers and a full 2.5" dual system will help the engine tremendously. Next is the tune. It is entirely possible the tune is off or that your particular setup needs attention beyond a mail order service. A street or dyno tune would also pinpoint any abnormalities or restrictions you are facing.

That being said I know for a fact my Vortec 383 is being held back by the stock exhaust manifolds/headpipes/cats and that the tune also needs adjustment. I faced the same thing you are facing now.

Doh! Forgot about that. Spiders Suck!

[haulinit]

The zz4 cam gets along just fine with manifolds but headers are always a good choice. On the same note I just went from the factory down pipes to 2.5" pipes with a x it did help it out on the old butt dyno. To the OP what did you use for a TC?

[SparKnocK]

If your referring to the torque converter its a D&E 2500 and since the build its about the only thing thats giving me hope. Truck probably wouldnt move itself without it.

[96ImpSS]

It's the tune. Bryan Herter at PCMforLess spent quite a bit of time to get mine right. Runs like a champ now.
I'd contact PCMforLess; they have the recipe ;)

[GreenVortec]

make sure the injectors are good..
shut them off/on one by one with a scantool and see if theres any change..