whitehooptie

Are the cool kids running these days? A number of years ago, it was the Patriot Gold spring/retainer/lock combo. Has anything better come out yet? I was thinking about going with a trex, ms3/4 or an LG cam. Something fairly big.

Eric D

If you don't mind doing a little reading, I would suggest this thread. It covers a number of the key items needed to pick a proper valve spring.

ZeeOSix

Eric ... in the thread you referenced above, you said:

I did tons of research on valve springs when I replaced them in my 2002 Z06. The PAC 1218 and PAC 1518 have the same exact force vs deflection specs, and only increase the closed valve force by ~30 lbs over the OEM springs. The fully open valve spring force (@ 0.551" lift) is basically identical to the OEM springs @ ~300 lbs.

The PAC 1518 springs have micro blasted surface and are nitrated for increased strength and reliability over the 1218s.

And actually a little stiffer spring should control the valve train more and reduce the chances of valve float.

Eric D

Zee, when I wrote the above there were differences. I don't know if the PAC spec's have changed since. The updated GM spring was validated on engine dyno and durability vehicles. Some of the most thorough testing anywhere.

It all comes down to a choice. For me, if I'm going to maintain a stock engine I would choose the GM spring. If the cam is changed to something different then by all means the springs and other valvetrain components should be picked to match the application and that might very well be an aftermarket spring.

The key point, you need to pick the springs to match the cam lift profile, the mass of all the valvetrain components and intended operating rpm. Just picking a spring without taking into account the whole system means something less than optimum and greater risk for component failure.

vettenuts

Sounds like the OP is planning a very large cam.

I would find out what the required seat force is for the cam selected to start with. From there you need to sort out what is required to control the cam. Over the nose forces can deflect pushrods and loft the lifter. I have seen many with damaged cams blamed on the cam itself when in all likelihood there were other mitigating factors involved.

Also, the MS4 (not sure on the TREX) is well below PTV clearance minimums. Be aware if you don't plan on fly cutting, a missed shift or some minor valve float will not have a very happy ending. Valve train control and rigidity will be very important.

ZeeOSix

I hear what you're saying Eric. My main point was that I think PAC 1218 or PAC 1518 springs based on their specs are a pretty good match to the stock springs. These PAC springs only increase the closed valve force by 30 lbs (which will not harm the valve train), and the fully opened force is the same with the stock LS6 cam. Now if the fully opened force was 100 lbs more, then obviously they wouldn't be a very good match for the stock cam and valve train components.

This is why I chose the PAC 1518s, because after all my research the force specs were a good match to the OEM springs IMO, plus the 1518s had the nitride treatment for increase reliability. I don't want to change valve springs again, so went with ones with what I felt was the highest reliability factor in a stock LS6.

vettenuts

The PSI 1511ML's are also a good beehive that I wouldn't hesitate to use in stock setup or small cam.

ZeeOSix

Here's a pretty good article about beehive valve springs.

http://www.enginelabs.com/engine-tec...-work-for-you/

Paul 75 L82

Springs need to match your cam and I dont believe in beehives. After breaking a spring my double spring saved my piston. I will always run a double spring.

whitehooptie

I'm not a fan of the beehives either. Maybe for a stock LS6 cam, but that's about it.

Eric D

This is a pretty good article and I agree on the many benefits of the beehive style springs. I can only find one little pet peeve of mine. Where spring resonance is discussed in the third paragraph, the use of the word, "dampened", as in something wet. Technically the proper word is damped. Same as using dampening in place of damping is wrong use of words.

The primary reason people fear using beehive style springs is breakage. The spring has to be properly selected for the valvetrain system. When the proper beehive spring is used it will greatly improve the total valvetrain performance and out perform any other style spring along with better durability.

WKMCD

FWIW: I've been running the same set of PAC 1521 springs on a couple of my builds. I've run cams up to .660 lift and now run .643 lift on both sides. When I did the 427 the springs had about 10k miles on them and when Richard at WCCH checked them out they were still within a couple of lbs of new specs and that was with the .660 cam. They've been controlling a 2.165 and a 2.200 intake valve. Not exactly small. They are in my 427 now and still going strong.

The PAC 1518 and 1521 are both nitrited and will last a VERY long time. the diff is the 1518 is a beehive and the 1521 is a dual.