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OUTSIDE DIAMETER
Most V8 engine valve springs have an outside diameter of about 1.50″. The spring’s specific outside diameter is machined into the cylinder head to create the valve’s spring seat. This is usually prevalent in two closely related engines: the 1967-92/93 A-engine (small block) and the 1992/93-2003 Magnum (small block).
The A-engine springs have a 1.50″ OD while the Magnum uses 1.42″ OD.
A-engine springs do not fit on the Magnum engine family. Machining the spring seats to the larger diameter is one solution to resolve this situation. This operation is commonly done for racing engines, but it’s expensive for a street engine and for just a cam change.
The best solution is to use a specially designed HP Magnum valve spring like
P5249464 and use retainers
P4452032 (no special machining required). This is good for valve lifts up to .525″ lift. If you need more lift capacity, then use
P4876062 spring (with the “032“ retainer) for up to .600″ valve lift.