I have read many posts about the issues, with that said i am a believer in changing them. I have a 2003 supercharged z06 with the intercooler, exhaust, and fuel mods 28,000 miles. I want to change them while it is still winter here and i can't drive it anyway. My question is this: is there a kit? to include trunions, springs, keepers, seals. I have seen some go with PAC 1518's and some go with GM, and some go with 1218's i am new to the corvette world and this is my first real sports car. I would appreciate any advice and why i should go with what you reccomend. I want to buy them asap. also instead of just buying the trunions should i replace the whole rocker to 1.8's. Will this bennifit my motor at all? I think this thread will help allot of people who want to replace them. also what is the deal with the dual spring instead of a single? Thank you in advance.

 

I'm not an engine builder but I can give you a little info based on my experience with normally aspirated LS1,6. Back in 2004 on my LS1 with a mild 224/224 comp 918 springs, broke an intake spring at about 10,000 miles, had to replace the entire set. Put about 9k on the new set with no problems. Comp had quality issues with their beehives at one time but have since corrected that. However that made some guys alittle leary about comp springs.

Many engine builders prefere dual springs as a safety measure, if you do fail the primary outer spring usually the inner spring will protect the valve from dropping into the combustion chamber. (luckily I didn't have that happen with the failed 918)Also, with aggressive cam lobes you reach a point where a single spring cant meet the requirements (lift, seat pressure, valve size, etc).

My present setup is AFR 210 heads tweaked by Tony Mamo at AFR with a more aggressive cam using comp XFI lobes. He specked out dual AFR 8019 springs with titanium retainers (similar to Patriot Gold Extremes) but this would be overkill for your stock cam.

I hear lots of good things about the PAC 1218s and 1518s and there are advantages to the beehive ovate wire design, primarily light weight and a portion of the spring weight does contribute to the valve train weight. I would probable go with the more durable 1518 with titanium retainers, you should be able to use the stock locks.

With your stock cam 1.8 rockers would seem to be a good upgrade. I would look at the Yella Terra Ultralights, I'm running the 1.7s with no problems. If you end up replacing the push rods and rockers make sure the shop checks the wipe pattern between the roller and the valve stem. The Yella Terras come with shims to adjust the install height of the rocker.

Hope this helps a little. I would recommend you give a couple of the forum vendors a call and run by them what you want to do, most are more than willing to discuss options and their recommendations would be better than mine.

Good luck, this winter has to end eventually, although I'm starting to wonder.

 

Thank you sir!

 

One other spring to consider since it doesn't appear you have a high lift aftermarket cam are the PSI 1511ML valve springs. These are excellent springs for this motor. I would shy away from the 1.8 rockers myself.

 

Why shy away from the 1.8 rockers...just curious?

 

anybody else

 

My suggestion is to contact whoever did the charger install and see if the springs have been changed.

If that is not an option contact ecs or a&a and see what they suggest as far as spring choices for your application.

I used gm ls2 spring when mine were replaced, then bought a set of pac 1218 because i just didnt find enough satisfaction in being that gm had really purged their inventory.

Can't comment on the rockers as im asking the same question trunion upgrade or spend more and buy aftermarket 1.8 which will add a few hp.

 

To be honest, if you are running a stock cam, then slap some Pac behives in there and call it a day. Cheap and reliable. I had them on my ms3 (238/242 .603 .608) cammed 02 Z06 for 15k miles or so, and never had a single issue. I have since switched motors and went to a dual spring. Im not crazy about how much valve noise I get now, but I feel the dual springs were safer bet with what Im running now (235/244 .621 .612)

The 1.8 rockers are one way to get a little more without a cam swap. I've always been one to do cam swaps instead of rockers/easy stuff, but thats just me. I do my own work, so it saves money and its something I enjoy doing anyway.

 

I'm also running pac 1518's with stock retainers and locks... I also installed comp's trunion upgrade and chromoly pushrods at the same time... I have an ecs big blower cam in my 02z and plan on supercharging it later this year... I only upgraded the trunions instead of buying new rockers because it will be making plenty of power once its boosted anyway and I'm not going for max effort

 

I am running a stock cam but what about my HP gain with the blower? Dosen't that add more stress to the springs? I didn't know i would see HP gains with new rockers. That would be a pluss. If all dual springs make alot of noise I don't think i would like that I kinda have OCD with my vette and it would drive me crazy thinking there is something wrong. Again thanks everyone. What is the differance from 1218's to 1518's I am really new to all this. Are rolloer rockers hard to install?

 

You should not run duals with a stock cam as most of the dual spring will have too much seat pressure that will cause premature wear to the cam lobes. The only difference in the pac 1218 and 1518 is the 1518 is nitrided during the heat treat process. This gives them extra durability.

 

Good info... So i guess the concensus is PAC1518's now what about the rest? and why please?

 

The 1518s are also micro bead blasted, so the surface is much smoother and that relieves any flaws in the spring surface that can cause stress risers. 1518s and 1518s have the exact same spring constant and open/closed seat forces. Pay a little more money and get the 1518s for sure ... a more reliable/durable spring.

I'd recommend the Comp Cams Trunnion Kit, and some good chrome moly pushrods while you're in there. Don't necessarily need new retainers & keepers with those low miles, but could if it makes you more comfortable. I'd put new valve guide seal in too while at it ... cheap insurance that they will be good down the road.

 

I think we are getting there. Is there any information that anybody knows of that gives instruction and torque specs on this subject. Maybe where to find it. also is there a place that sells a kit with the PAC1518s, push rods, comp trunions, and seals maybe retainers and keeper as well. If i buy the vale spring tool do i need to be at top dead center for every set of springs? I guess the tool is TFS-90306 from summit? Thanks again....You Guys are great. I just hope one day i can help someone else out...

 

How about new rockers over the trunion kit? And why please

 

I personally like the BTR Platinum kit with the trunion upgrade.
http://forums.corvetteforum.com/c6-f...-kit-sale.html

 

I bought my 1518's from ws6store, pushrods and proform valve spring tool from speedinc, and trunion kit from coloradospeed... I don't think one place sells all those specific parts as a kit, I just searched around for the best prices and all of those places are good to buy from... the rockers are 22ft/lb's and it doesn't matter if you are on tdc when you swap the springs but there is a proper procedure to torque the rockers to keep from damaging the threads in the heads and/or getting an improper torque reading

 

If you're not using compressed air to keep the valves closed, the piston needs to be pretty close to TDC to prevent the valves from dropping too far down when the springs are removed when working on each cylinder's valve set.

 

The PAC 1518 (beehive) and 1521 (dual) are both nitrited springs that will last you a very long time. I've been running the same set of PAC 1521's through three builds and they still measure within an lb or so of new. I've run them with cams up to .660 lift with the heavy 2.200 intake valves I'm running now.

They are expensive but in this case...you really do get what you pay for.

FWIW: I've broken 2 YT rockers and can't wait to get them out of my motor.

 

Any other suggestions please