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MHS / PAC RPM Series .500" Lift Stage 3 4V Valve Springs
.500 Lift - No Machining Required. Includes 4130 Chrome Moly Steel Retainers. Suggested for Turbo applications over 25lbs of Boost.
MHS / PAC Stage 3 RPM Series 4V Valve Springs
These MHS / PAC RPM Series Valve Springs are designed for use with 4.6L / 5.4L 4V B, C, 03/04 Cobra / Mach 1 and Navigator Cylinder Heads. They are supplied with your choice of 4130 Chrome Moly or 6AL-4V Titanium Retainers with a +.050" Design to raise the Installed Height from the typical 1.430" to 1.480". These Valve Springs have been through multiple anti-fatigue processes and work very well on High Boost / High RPM applications. Good for anything from 10lbs of boost and 6K RPM to 40lbs of boost and 9500 RPM. We have tested these springs after over 300 passes at 9000+ RPM and have not seen any signs of fatigue after checking every single one on our spring tester. Less than 1% change in seat pressure and spring rate.
There really is no need to go any higher than .480" Lift on Non GT500 Style 4V Cylinder Heads. Although these springs are more than capable of handling .500" Lift at a 1.480" Install Height, there really is no reason for it and .480" lift is our suggestion for these springs.
We also encourage everyone running aftermarket 4V cams and valve springs to upgrade to the Accufab Secondary Timing Chains as the OEM Secondary chains were just not designed for much more spring pressure than stock.
|Seat Pressure||115lbs @ 1.480"|
|Open Pressure||230lbs @ 1.000"|
|Spring Rate||240 lbs / in|
- Item Requires Shipping
- 4.0 lbs.
- W8.0000” x H8.0000” x L8.0000”
- Free Shipping!
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