It really depends on the lifters and how much preload they require.
There is a time and place for new pushrods.
Trend Performance - About the Company and Founder Bob Fox
It all depends on how things go together. Sometimes you need longer or shorter pushrods. For instance, roller lifters are taller than solids. They also have require more spring pressure. The solid for my black '66 Charger calls for 900 over the nose and 300 on the seat.
If you put together an engine that takes advantage of a t&d setup and you have valve spring pressures that handle stock pushrods t&d rockers are overkill for the application. Solution - buy roller lifters, solid roller cam and....new pushrods! : D
If you are using a juice cam you might find the adjuster out there a ways if the lifters require .045 of preload to quiet things down.
From
www.compcams.com
Rocker Arm Adjustment/Lifter Preload
All but a few Chrysler engines were equipped at the factory with non-adjustable rocker arms. Anytime a solid lifter camshaft (either roller or flat tappet) is used, you must also use the adjustable rocker arms and appropriate pushrods.
When installing any high performance hydraulic camshaft, the lifter preload is something which must be considered. Too little preload will result in a noisy valve train, and too much preload will result in tight valves and a poor running engine. Either condition can result in less than expected performance or engine failure. After the cam, lifters and rocker arms are installed and prior to installing the intake manifold, you must check the plunger depression in the lifter. With the cam on the base circle (valve closed) the plunger in the lifter should be depressed .040”-.060”. With nonadjustable rocker arms, you must change pushrod lengths to obtain proper lifter preload. This is a delicate and time consuming process, so if you have any questions, contact the CAM HELP® line at 1-800-999-0853.
