Community Q&A Question: VALVE SPRINGS

Asking About: Mustang Ford Racing GT40x Cylinder Head 64cc (79-95) 5.0L/5.8L



What's the sping rate on the valve spings that come with these heads? Do I need to upgrade the bee hive valve spings to run an X303 cam?
from San Diego |
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Accepted Answer
These come with the M-6513-A50 valve springs. Seat pressure is 123lbs at 1.800'', and Open pressure is 303lbs at 1.250''. The range Ford Racing recommends for the X303 cam is 120lbs seat pressure, and 295lbs open pressure, so you would not have to upgrade the springs these come with. It is very important to check piston to valve clearance.
from Hewitt |
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