Setting up a big-block Chevy Valvetrain is incredibly easy. In this tech installment, we'll show you how to properly set up a set of Dart BBC adjustable pushrod guideplates.
From horsepower to engine longevity, valvetrain geometry is everything. And, in the world of big-block Chevrolet engines, some finessing is almost always required. Due to tolerance stacking on factory blocks, varying aftermarket components, and about 10,000 other reasons, adjustable pushrod guide plates are a necessity––something Dart Machinery founder, Richard Maskin realized a long time ago when he patented the big-block Chevy adjustable guideplate.
Before that product was introduced, engine builders had to cut, tack weld, check, repeat to get their rockers to correctly align over the valve stems. Now, the process is much simpler, extremely adjustable, and can be handled in no time. In the photos below, we'll walk you through the entire process of setting up adjustable pushrod guideplates for a big-block Chevy head.
Shown is a standard, solid guideplate vs. a Dart adjustable guideplate. The adjustable plate is a two-piece design held together by an allen-head screw and locking nut. Note: the piece stamped *DART* always goes on top.
Shown on this Dart aluminum Pro 1 head are the threaded holes designed to accept screw-in rocker studs and adjustable guideplates.
The guideplate has a raised and lowered end that accomodates both the intake and exhaust pushrods. It will only fit on the head one way.
Thread in the rocker studs through the guideplate by hand, making them snug, but allowing some movement in the guideplate.
Tighten the guideplate's allen screw so it is snug, but not overly tight. The trick is to allow them to move slightly when force is applied.
Install both the intake and exhaust pushrods in the respective guideplate slot. We used Trend Performance pushrods for this engine.
Next, a Comp Cams aluminum rocker arm was set in place over the rocker stud and the position of the roller wheel was noted.
Note how the rocker's roller wheel is slightly off center on the valve stem? This is the issue adjustable guideplates are designed to correct.
Using a drift and dead-blow hammer, lightly tap the guideplate to move it backward or forward. As the guideplate rotates, so will the rocker arm. Check the rocker alignment after each tap with the hammer.
Continue to tap and check the rocker alignment until it is dead-centered over the valvestem, like shown.
Next, use a torque wrench to tighten the aligned rocker to spec, making sure it does not rotate. Move to the next rocker and repeat the process.
After the job is done, both rockers should be perfectly centered over the valves like shown.
