I believe in dual springs. I had a 383 stroker in a Camaro and broke a spring, no damage other than the spring and the pushrod. I would never install a single spring after that. It was a $11k motor with 200 miles on it, it can happen at any time.

Ouch.

Dual springs can be tricky...you don't want them to be too stiff. I've read about folks wiping out cam lobes with dual spring set-ups because the springs were too stiff. I agree they sound like great insurance, but I don't think they're for everyone. Also, if one of the springs fails (inner or outer)...yes; you avoid serious engine damage initially, but you have to be astute enough to know that you've broken one of those springs before the secondary one fails. Just my $0.02 :cheers:

Let me tell you, I broke the outer spring and you knew it. Motor ran like crap, there was no way that breaking one of the springs and the other keeping the valve up you were going to keep driving and not know it. The inner doesn't hold the valve all the way up, it was hanging lower and you sure can feel a valve staying open.

So does anyone have any information on WHY the stockers are failing? Is it a fatigue issue? Pitting?

The "yellow" springs what is different about them?

I put a lot of trust in the General as they have been building these engines for a long time and I would hate to mess with long term reliability by putting too much spring in the valve train. The dual springs would have to have an equal (or very close) spring rate (added in parallel Ktot=Kinner+Kouter).

But if it has been determined what the root cause of the failures were then we wouldn't have to go to a redundant spring setup.

Btw, I like the idea of replacing springs that have the capicaty for more lift! This seems like a good pre-modification for a cam!

Good to know if that's the case.

I've got a new set of the PAC 1518's on my workbench, but I'm thinking about using the Patriot Gold dual spring set, which comes complete with valve stem seals, locks and titanium retainers for $255.

I might install the Yella Terra 1.7 roller rockers as well, for $450.

I bought the Crane spring tool, which does 2 springs at a time, and I plan on using rope in the cylinder instead of compressed air. While I'm there, the plugs and wires will be replaced too, even though my '03 only has 18K miles.

Why not 1.8 rockers...unless you're planning a cam swap at a future date?

I plan on sticking with the stock cam, I want to maintain stock valve train geometry with the 1.7 rockers.....

Nitriding most certainly hardens metals, but not sure of its use in a spring.

'95 M3's under sustained high rpm applications (Autobahn, Racing) started spitting valves due to the keeper failing. BMW added a Nitride step to the process in production 10/95 and dealer stock 5/96 and no more failures....One of the first steps most owners with pre-10/95 cars is replace them! (I did!)