Brake Proportioning Valves The True Story of a Misunderstood, Misused and Misnamed Brake System Component by James Walker, Jr. of scR motorsports.
Originally Posted by TK6. I got the PAC1. 21. PAC1. 21. 5s as they have less pressure. Hmmm. If K RIPPER is right about the stock LS6 springs 9. I have a question about the 1. LS6 cam. PAC claims 2. LS6 spring measurement. PAC 1. 21. 5 would only have about 2. If the GM spring is rated at 2. I doubt GM put much extra stiffness into their valve springs, rather, I bet they did a PILE of testing to get them just above the minimum requirements for the cam profile. Looks like the 1. LS1 spring replacement, not an LS6 spring raplacement. On that same note, the open force on the stock LS6 cam for the 1. Looks like PAC has designed a spring thats taller than the LS6 spring with a lower K value. This looks like a no brainer replacement. For 6. 5 extra from SDPC the 1.