allthrottle&nobottle

As some of you may remember I broke an Exhaust valve spring on my stroker back in October of last year. I replaced both intake and exhaust springs on the #6 cylinder only as I did find a factory defect causing a stress riser and an untimely spring break( Of course hitting the rev limiter doesn’t help either )
I finally had a chance to test the old Pioneer intake spring that did not break and a few of the new Patriot Performance Gold springs. (Thanks to Steve & Rob at Abacus) The results would tell me if after 7K hard miles I need to replace all 16 springs or just the 2.

Used 7K+ mile Pioneers from Cartek’s 4X heads

Installed Height 1.800" = 120lbs

Valve Spring Open Pressure 1.200" = 370-375 lbs


Brand spanking new unused PP Golds (Note, these will lose ~10% strength after break in)

Installed Height 1.800" = 145 lbs average

Valve Spring Open Pressure 1.200" = 375 lbs average

Based on my results and continued good performance I WILL NOT CHANGE ANYTHING ELSE AT THIS POINT

And for some good FAQ on the above here is a good place to go.

http://www.cranecams.com/?show=valveSpringsFAQ

2c5s

iTrader: (11)

I thought most all springs lose 10% after break in. That's why they all get a bit "of" shim.

CaptUSA

iTrader: (5)

Wow, very cool stuff.

So is your beasty up and running now?

allthrottle&nobottle

Oh yes w/o issue............
All spring loose ~10%.........my example showed how good the Pioneers are after some hard use...........couldn't find the exact specs from the manufacturer......yet