after doing a lot more digging than the average bear would do about this for two weeks, i have come to a conclusion. GM is very annoying.

Comp Cams tech bulletin.

GM introduced a second style VVT cam actuator (aka phaser) in 2007 and ran two different cam
actuators through 2007‐2008+. The new style became the exclusive unit in most 2009+ engines.
•Original (old style) GM Part #12585994: 2007‐2008 (uses cam core 156‐)
•Current (new style) GM Part #12606358: 2007‐2009+ (uses cam core 189‐). The difference in
camshaft core is the pin to centerline position.
The difference in the pin between 156 and 189 equates to 13 degrees cam retard (if a 156 is used
where a 189 is required).

upon more research, it all makes sense now, and how this bulletin comes into play. some may think "duh" and others will look at it and say, "well it makes sense now"

this is how it affects you and your part numbers.

on the front side of your cam actuator {phaser} there is a three digit number. 994, or 358. compare this to the numbers above and you will see where it comes into play it.

99% of the people will order a 156-40x-13 cam. then some will complain about a loss of low end torque and the sudden rush of top end. bells ringing yet? if they ordered a 189-40x-13 the torque would have cam up and the same about of top end would have been had with great midrange.

now there is a slight problem with ordering a 189 cam core. 9/10th of the time most vendors won't stock it because most go off the websites, and the 156 number comes up.

one vendor actually asks what year the engine is, and gets you the right phaser limiter and matching cam. TSP.

so when you want to order a vvt cam, make sure you are getting the right cam core, and phaser.



How to install the comp cams phaser limiter block courtesy of Sand Man
http://www.youtube.com/watch?v=Tsj4anpULX0

 

AWESOME analysis!

Your detective work might have just saved a few members from a lot of heartache, and explained a few ongoing problems for guys.

 

I laughed when I read this because I was just reading about a vvt swap in an s10 and was complaining about how he had no low end and then picked up at the top. Everyone there was stumped, I'll have to post this link. I'm going to go out on a limb and say this info should be a sticky.

 

I agree. Posted for the bookmark, thanks for the heads-up, now get a mod to stick it!

 

Stuck!

Thanks for the info!

 

i ran into numerous threads in my search about that. the more i dug into it the more and more i saw a common problem.

YaY sticky!

 

Another good thread from a couple weeks ago about the cam cores
To vvt or not to vvt - LS1TECH

 

thats one of the threads that spawned my information hunt. along with a whole crap load more of em in roughly the same content

 

Comp will have my custom grind 189 done next week and I should have it in shortly after that. I'll post the differences from the old "butt dyno" and data logger software.

 

Mind sharing the specs on that cam Gus?