That sounds awesome man!
I hope someone chimes in here who knows a lot about custom tuning the older trucks... i dont have a lot of first hand experience doing it, but I do know that you cant get out PCM ot go past 5800 no matter how you program it. I think they will be able to tell you better.

-Rob Nap

 

I have talked to most major PCM tuners in North America and no one has gotten a Vortec 350 PCm to rev over 5800 rpm.(Westers, Fastchip, Nelson Wait4me etc, etc).

Even with my Tunercats 2 tuning software I can set the rpm limit to 9000 rpm if I want but the injectors are not fired over 5800 rpm. Kinda like trying to rev an LT1 over 7200-7300 rpm, the injectors wont go.

It would be nice to confirm a rev limit of over 5800 rpm with an accurate tach(certainly not the factory tach) and on a scan tool.


If you swap to the 411 PCM from a 01-02 fullsize Van which also uses the Vortec 350, there have been reports of a 6200 rev on a stock tach. He let off as it was a stock 305 with twin turbos, and he didnt want to frag the engine.

Also you can run up to 0.550" lift on stock Vortec heads if you run 915 or 918 comp cams springs with the Beehive rertainers in the GEN 1-2 valve stem size(different than teh GEN 3/4 valvestem diameter).
peace
Hog

 

hog, If you were in the Houston area I'd prove that someone's BS'n you on the 5800. I guarantee I can go to 8000 RPM. Fastchips said they they've never heard of not going over 5800 RPM but we must be getting conflicting stories. In fact I will meet anyone in the Houston area and I'll put my PCM in their truck just to prove it. I will not be responsible for any damage from excessive RPM though. I have no reason to lie. BTW, .550 on stock heads is pretty excessive. you'll get coil bind and pinch the oil seals eventually. I was pushing .522 lift and made 50,000 miles when I broke the springs but I was burning oil from the pinched seals before that. The Fastburn Vortec heads can handle .530 lift so you would have to machine the stock to handle it. I pushed mine to the limit, that's why I have an LS1 now. Been there, done that. I'm not going to say it won't work but be prepared to pay the consequences.

 

One other thing. I ran into push rods rubbing on the through holes in the 4 sets of stock
heads with .480 lift or more cams and excessive RPM. I'd recommend opening them up 1/8" if running over 6000 RPM. I even rubbed a set of my own pushrods the first time I went over .500 lift.

 

I can't speak on the over 5800 rpm debate, but I can promise you can run a little over .500 lift on unmodified vortec heads, with beehives, matching retainers and offset locks. I set up Vortec 350's that way and several others without a single issue including pushrod rub, as long as your using 1.5 rockers. The good thing about using the +0.050 locks is that you will be setting the springs up at an installed heigth closer to what they were designed for. Typical small block springs at 1.75" versus beehives at 1.8".

 

1Bear, I didn't say every set of Vortec heads just 4 and a set of my own. I'm going to back off on the Vortec heads and RPM because it always turns into a debate. I'm just posting past results. You might get lucky and get a long rung with a set of springs but it's hard to get away from the coil bind since the stock heads were "desinged" for .480" or less lift. Do a search for Vortec 350 or L31 max valve lift and see what comes up. Chevy High Performance and GM High Tech all come up with low numbers and the Fastburn heads come up with .530 or so. You can put any size cam you want including .700" lift but like I said eventually 20,000 to 100,000 something is going to give depending on your driving. If you don't have alot of money and your L31 is a daily driver, stay with a lower lift cam. My offer still stands with anyone in the Houston area with a 97 L31. We can meet up, put my 97 PCM in your truck and then post results. If I'm wrong, I'll be glad to apologize to everyone here.

 

I am one of the guys that couldn't go over 5800 rpm. My PCM was tuned by F.A.S.T. in Memphis. I installed a 12200411 Pcm into my 98 GMC and am using EFILive. I have gone to 6200 ( on the stock tach ) with this Pcm--Don't want to go higher right now on the 305. Still need to figure out what the 411 wants for a crank relearn. I am going to concentrate ALL my energy this weekend to try to figure that out.

 

Nobody is BS's me, these are the cold hard facts I have concluded afer asking Pro PCM tuners to raise my rev limit, Ed Wright at Fastchips included.


There is no way a Vortec PCM will allow 8000 rpm, a tuned LT1 PCM wont rev over 7300-7400 rpm, the PCMshuts the injectors down at 5800.
peace
Hog

 

Your right about the Vortec's being able to only handle around .470 to .480 stock, hence the offset locks. If you add the .050 the locks will give you, you end up with .520 to .530.

 

Then add the Beehive retainers used for the Beehive 26915 and 26918 springs and you can run 0.550"lift.

Even with teh stock valve locks WITH the Beehive springs and matching retainers you can run over .500" valve lift safely.

peace
Hog