JCPERF

Sorry bro

Panic Button

How do Comp Cams 939's stack up?

1.540'' (936-975)
I.D. .697''
Seat Load 161 @ 1.900
Open Load 418 @ 1.350
Coil Bind 1.225
Rate(lbs/in) 468
Titanium Retainer 249-732,721-16
Steel Retainer 249-741-16
Cup Seat 249-4700,4770,4771,4783-16
Shims 249-4757-16

mcollinstn

why not gold stripe 9905's with a touch less preload (for 150 on the seat)?

and I can't get isky's catalog to give me detils on the springs. some java script error.

rmbuilder

The 8205 spring is dual with damper, chrome silicon wire
140# @1.900” / 430# @1.250”
440# rate
1.170” stack
The 8205 SP is a different inner and outer wire, outer being Super Clean Chrome Silicon with an advanced heat treat to increase fatigue resistance
150# @1.900” / 440# @ 1.300”
480# rate
1.150” stack
The 8205 Plus is again a different outer wire
150# @ 1.900” / 420 # @ 1.300
440# rate
1.120” stack
The differences in the springs are:
Wire material grades
Heat treat of the wire
Shot peen
Nitriding
Surface preparation
All of which alter the natural frequency, fatigue resistance and load loss of the spring
The upper grades are made for Isky by PSI
Bob

rmbuilder

Mcollinstn,
The 9905 Tool Room spring is an excellent spring however seat @ 1.90 is 165#. If you install @ 1.930" you can lower the seat force to 151# and the nose to 436# @ 1.330" given the .598"/.610" lift at the valve. The chance you take is the 9905 spring stacks @ 1.160". Max lift will occur at 1.330", putting the spring .170" from stack open, with .080"-.100" being the optimum.
Bob

Sonny Spectre 30

Now this is what i am talking about! Thanks for all of your responses.

Sonny