I'm going to go through the top end of my Z06's LS7 this winter, send the heads out for porting and overhaul and try a different cam while I'm at it. The goal is off idle to redline performance. I'm not looking for peak power gains, per say, but a nice flat torque curve and good street manners. I do not race. The car is my personal toy and I just drive it to drive. It's making 525 whp now, and it's a hand already above 4000 rpm. If peak power is increased, I'll take it, but I certainly don't 'need' it.

I am still undecided if I want to put the money into a rail rocker set up, but I am somewhat inclined to go this route. The only rail systems I've had my hands on before are Jesel, and they were all race builds for others. After some cursory investigation, Jesel is definitely outside of my financial threshold of comfort. I'm not cheap, but frugal when I'm paying the bills.

It looks like T&D and Crower both offer rail set ups for these heads. I am unsure of any other manufactures. The T&D and Crower are both closer to what I'd be willing to spend, but I have ZERO experience with either, I'm not sure if I want to go with either without some reassurance from those who have used them.

The other, and also much less costly option is to simply upgrade the OEM rockers with Comp's trunnion kit or have CHE bush them. The CHE option doesn't sit well with me though. It looks as if splash is the only way they are oiled and I'm not sure if that's adequate for a bushing.

The reason I am considering a rail system, is to get a roller tip without adding excessive over the nose weight, and from the feedback I've received from a few friends, the general consensus is that there is no pedestal mount full rocker for this engine that has proven reliability. I plan to run a cam with lift of no less than 650 and it troubles me to run this much lift without a roller. And then of course there's the standard valve train stability benefits with a rail system.....but damn they're expensive.

I also intend to run Ti ex valves unless I can find a solid SS with a comparable weight to oem sodium filled valve. I haven't found any yet that isn't at least 15 grams heavier. I hate two piece valves for reason's I'm embarrassed to speak about, so regardless, the oem's are not going back in.

If anyone has any hands on experience with the different LS7 rail systems, or any other input regarding my plans, I'd appreciate your feedback.

thanks.......mike

 

I can set you up with a proven cam that will put a HUGE smile on your face and still be very street friendly! PM me for details...

 

Roller tips aren't going to make as big a difference as you might think. I would bush or otherwise replace the trunion bearings and concentrate on cam and induction. Hell some Cup teams have gone away from the roller tip and lash adjusters, and have gone to lash caps. I would assume this would be to reduce weight and prevent failure opportunities. If it's good enough their stuff banging away at 9k all afternoon, good enough for me. If you look around here enough you will find a picture or two with this setup for an LS7. I have seen it on this site.

 

Yella Terra ultralights are mini-shafts (shaft per rocker pair) that are lighter over the nose then stock rockers, and roller tip. YT6670s fit ls7

 

I'm assuming they are still using a rail system though.... I can't imagine they would forgo that and go ped mount.

My issue is side loading with this much lift and longevity. I plan to buried in this car, many many years from now.

 

They are still shaft mounts. I found a video of the Toyota Cup engine cutaway at SEMA that shows what I am talking about.

http://www.youtube.com/watch?v=rh-1dp0vSAo

 

Thanks for sharing the link / video. That's pretty damn cool.

It does look as if they do not have a roller tip. It's too hard to tell if there is a radius on the rocker though. Roller tips don't actually 'role' much, but they do offer a smaller footprint on the valve.

 

I was at SEMA, and saw it in person. The tip was radiused similar to what a stock rocker design is. I am sure whoever designed it matched the radius of the heel to the travel range of the rocker to minimize wear and distance traversed across the tip of the stem/lash cap. The valvetrain in these motors is a lot different than a normal high performance camshaft design. Instead of the lifter following the camshaft profile, at speed the valve is lofted and thrown higher, faster than the physical cam profile. The springs, camshaft lobe, rpm range and valvetrain are specifically matched to accomplish this. This tech has been around for quite a while, when I was racing karts, this was all the rage starting in 1995. Very hard on parts and probably impossible to do correctly without a spintron (without breaking a ton of stuff). Probably tough to keep roller pins in the rockers with that kind of hammering.