Stiggy Pop
In the cool kids club
- Joined
- Feb 27, 2011
- Location
- Granville, MA
I'm working on a custom valve train with Ferrea Racing and we are trying to walk ourselves into a good spring selection (beehive or conical). I do not have much to draw from when it comes to spring pressures, so thought a straw poll here to see what others have done might provide some data points.
context:
8v head
48mm intake, 40mm exhaust valves
.490" lift cam
SuperTech cam followers (https://www.supertechperformance.com/p19472-cf-37-3-9-cam-follower)
7k rpm & 30psi boost pressure ceiling
The previous setup was RSI bugpack springs which had 95lbs closed and 205lbs open pressure. This poorly chosen combination caused problems inherently, but interesting to note that after ~5k miles run time the springs showed 86lbs closed, 185lbs open. A ~10% loss.... junk.
Some of the springs we've looked at initially would net somewhere around 120lbs closed, 250lbs open. My primary concern is with open pressure, and whether or not I'm going to wipe out the cam or the buckets.
Recognize I'm not running anything stock but would still be interested to hear what people have done with stock Volvo buckets and shims.
Anyone changed guides to run 7mm diameter valve stems?
context:
8v head
48mm intake, 40mm exhaust valves
.490" lift cam
SuperTech cam followers (https://www.supertechperformance.com/p19472-cf-37-3-9-cam-follower)
7k rpm & 30psi boost pressure ceiling
The previous setup was RSI bugpack springs which had 95lbs closed and 205lbs open pressure. This poorly chosen combination caused problems inherently, but interesting to note that after ~5k miles run time the springs showed 86lbs closed, 185lbs open. A ~10% loss.... junk.
Some of the springs we've looked at initially would net somewhere around 120lbs closed, 250lbs open. My primary concern is with open pressure, and whether or not I'm going to wipe out the cam or the buckets.
Recognize I'm not running anything stock but would still be interested to hear what people have done with stock Volvo buckets and shims.
Anyone changed guides to run 7mm diameter valve stems?