Magnum Valve Lift - How far can the rocker go?

[Bruceynz]

Hi Guys,

I have a .533" lift cam, what is the maximum I can get away with the factory rockers before it will start spitting out push rods?

Also what is a good option for rockers if I need to buy some? (I am not racing, street engine)


Engine: 5.2L - 5.9L Magnum
Camshaft Type:  Hydraulic Roller
Basic RPM Range: 1200 to 5700
Valve Lift Intake: .507
Valve Lift Exhaust: .533
Duration Intake: 274
Duration Exhaust: 278
Duration at 050 Intake: 221
Duration at 050 Exhaust: 225
Lobe Separation: 110
Intake Centerline: 108
Firing Order: 1-8-4-3-6-5-7-2


Thanks
Bruce

 

[XfbodyX]

Its gonna take a better spring, still could probably find a single, but if your rockers are in good shape and your not beating it I think youd be ok.

You using the 1.6 oem rockers?

Id also look hard at the ex side retainer to seal clearance.

 

[Bruceynz]

Hi,

I Have these springs and retainers, see red arrow

 

[Oldiron440]

Aren't the magnum heads limited to .525 lift without machine work?

 

[Bruceynz]

As above, mopar performance make a special spring and retainer to allow stock mag head up to .600" lift with no machine work.

 

[XfbodyX]

I would of been tempted to go with the spring one up from what you picked and check coil bind and added the proper shims if needed to get the right coil bind. But since you have them that doesnt matter. The cam companies try to state the .060 just to save there ass, ive ran as tight as .070 combined in street strip applications. But there is a happy middle ground for a off the shelf spring.

Id consider a entry level adjustable rocker or at least anticipate possibly needing a different set of push rods due to factory inconsistencies of oem rockers so you get the proper lifter preload. But in the end if you check everything on every rocker, every installed height, you will know right away if you have too much or too little preload. On top of checking on install if it breaks up in the higher rpm is a sign of too much and if you find a hint of noise on fireup sometimes that indicates too little.

What lifters do you have?

 

[Bruceynz]

I have stock replacement roller lifters.