How much lift for Vortec 906 heads??

[87Aero]

I've run across a thread once that mentioned what they were good for stock. Ithink it may have listed the springs and retainers, ect that needed to be changed from stock. The springs and all look a little wimpy. I'm thinking about a ZZ3 cam or something with some street manners.

What do you recommend?

 

[Doober]

Re: How much lif for Vortec 906 heads??

I have a Comp XE268 in mine (.477/.480) without any problems. Excellent street manners.

 

[87Aero]

Don't the stock springs, retainers and keepers need to be replaced? I thought I read somewhere that the factory stuff was weak and not to use it with a cam any bigger than the stock one.

The black PCM's have a 5800 rev limit. How tight have you wound yours?

 

[Doober]

I have a carbed intake on mine, I don't think I've hit 6k, but it's probably been to 5,500... most of the time it's been spinning the tire(s) though. The heads I bought from the junkyard, disassembled/cleaned/reassembled, and installed with the cam. Ran it for 2 summers so far without any problems, but I think .480 is probably the safe limit for them without work/changes. I can see the keeper gets close to the valve seal, but doesn't quite touch it.

 

[D&A Machine Shop]

.480 is pretty much the limit with the stock setup.
The guides need to be machined down in order to run a bigger cam.
There have been a few other threads about these heads in the last couple of weeks look them over there is some good info in them.

 

[87Aero]

I'll search again. The first time I was having trouble with my computer telling me the server timed out.....over and over again! I got aggravated, and just asked.

 

[Doober]

Take a look at this article. Doesn't go into extreme detail about Vortecs, but gives an idea of how easy it is to make power with a set. I based my motor off it and it's an excellent runner
http://www.carcraft.com/techarticles/ccrp_0403_350ci_small_block_chevy_engine/index.html

They also outline the changes they went through to run a GM HOT cam, and its gains (hit 400hp with it). I may change to this cam (maybe something slightly bigger) in the future, but I think I'll be knocking on the door to a set of 10:1 pistons.

 

[Dyno Donny]

GM use the vortec heads on the 602 racing crate engine. They have used both the 906 & the 062 heads. The stock springs work well on a low RPM, low lift application but if you go up on the lift or RPMs, then expect trouble. http://www.d-aperformanceengines.com/crate pics.htm. There is a couple of pictures here that shows what can happen if you go to high on just the RPMs. They go into valve float and destroy the valves, locks, retainers and then the engine. Do yourself a favor and beef up the springs and cut down the guides to work with your combination.