Mac 108

I have an 03 Z06 all stock with 35k miles that just broke a valve spring. I want to replace all of the springs, but I am not sure which springs are appropriate replacements. I would prefer to upgrade to an aftermarket spring. From what I have read, it seems that it is not uncommon for Z06s to break valve springs.

I plan on keeping the engine stock. The PAC 1218s have been suggested to me, but what is my best option for a stock 03 LS6?

eamador11

Comp 918s or Manley

Mac 108

I've read about a lot of failures with Comp 918s

Hardtop

iTrader: (3)

PAC 1218's

02*C5

iTrader: (1)

I have Comp 921s and they are on their second HC package. Both cams are fairly aggressive and they are all still square and are with in compression specs.

vettenuts

iTrader: (4)

You have a very light valve train and a relatively mild cam. I would discuss with PAC but I think the 1215 might be a better fit. The stiffness is the same as the 1218 but they will set up lighter on the seat. The other option, and this is an excellent long mileage spring, is the PSI 1511ML. Both PAC and PSI actually make their springs, Comp does not. I personally wouldn't go crazy on seat value with those valves, its not required and they are weaker then one piece valves.

Also, not sure if you are aware, but from what I understand GM updated the LS6 valve springs to a better spring then those that came with your car from the factory.