I've been told the PRC Duals are rather loud.. My buddy has them on his MS4 in the 02 SS.

Any other VS's to recommend for a .637 .639 lift cam? Comp 921's??

 

How can a spring be noisy?

 

^ I dunno.. My buddy told me that his PRC duals were noisy.. But then again, he's got the MS4 cam... so the sewing machine noise is a little mroe than usual.

 

Any relatively aggressive aftermarket cam and springs are going to be noisy on an LS1.

 

That's due to improper valvetrain geometry. His pushrods are likely incorrect. I have that same cam and springs with a properly setup valvetrain and my engine is very quiet - very little valvetrain noise, and certainly no sewing machine noise.

 

Sounds like not enough lifter preload to me...aka too much valve lash.

 

I find most of the valvetrain noise from my Spintron comes from the valves closing back on the seat.

More lift, the greater the closing velocity, the louder the valvetrain usually.

 

^Just out of curiosity, but how durable are the stock valves w/ .639 lift and LSK lobes??


Doing some HW on spring rates and what not.

Comp 921’s: rated for up to .650 lift

O.D: 1.300
I.D: .870 (outer spring)
I.D: .655 (inner spring)
135 LBS @ 1.770
400 LBS @ 1.220
COIL BIND @ 1.040
MAX LIFT .650






PRC Dual Spring Kit: good for up to .660 lift

seat : 140lbs
open: 390lbs
install : 1.800
coil bind: 1.07
1.290 O.D.
max lift : .660
matl : super pure chrome silicone

 

Update:
I think I'm gonna go with the PRC Dual springs. I'll save for the TF or AFR heads while I'm deployed. -I'll do a bit more research on them. Swirl and CYL filling abilities.

 

PRC and Patriot golds are the same. Go with which ever one you find cheapest. Speed Inc was for me w/free shipping etc.