question on stock rockers for small block

[74sat318]

On stock rockers(non adjustable) is there a rule of thumb or situations when you will need to switch to adjustable rockers, looking at making a cam change and wondering if I can keep the stock rocker set up on my 318 motor, I know I have to get new valve springs to match cam. Duration of cam at .050 is INT-227 EX-241, Lift INT-.486 EX-.473 , its a hydraulic flat tappet cam

 

[69 Runner]

That cam has more lift on intake than exhaust, but less duration on intake than exhaust?

 

[Cranky]

If you want to stay with the stock type rockers, at least go with the heavy duty ones from Mopar Performance. The stockers from the factory are kinda light and a push rod may push through it. Also keep in mind that rockers and shafts are a wear item and should be replaced at rebuilds etc. A friend has the MP ones on a 318 and turns 6200 with it....480 lift cam.

 

[74sat318]

The cam is Comp Cams Thumper series, its the smallest of the three in the series, yeah its got some wierd specs, I am going to go with new heavy duty rockers from Mancini Racing along with there new shafts

 

[q-ship]

If it were me, I would stick to the stockers if they are in good condition.

To answer your original question, the only time you NEED to go with adjustables is if you are running solid lifters. You are "better off" with adjustibles if you have milled your heads or block a bunch (.060 or more), or are using ultra heavy valve springs that could damage the stockers --- the cam you are contemplating won't require such heavy springs, --- and even if you were using one that did, all but the best adjustable aftermarket rockers will wear out quicker, than say the 273 stock iron adjustables, and any would need heavy duty pushrods if the springs were that heavy.

Spend your money where it can be of some use, not on things that aren't necessary (or probably worse than what you have).