The E-Street heads will also offer flow improvements over our 906 castings. The 906 heads on our 383 have a little bit of match-porting and bowl work done, but the E-Street heads provide better flow and an improved combustion chamber, equaling enhanced performance, right out of the box. In applications with a larger than stock camshaft, like ours, Edelbrock recommends installing adjustable rocker arms rather than using the factory, non-adjustable units. Comp Cams Pro-Magnum rocker arms are a great choice, offering a lot of benefit for the cost, so we ordered a set of their PN 1621-16 roller rocker arms for our big-block. We also ordered Edelbrock’s PN 8591 head bolts, a pair of Fel-Pro PN 1009 head gaskets, and a PN 1214 intake valley gasket to complete the installation.

The E-Street heads install just like factory cylinder heads, and the head bolts are installed and tightened in the standard sequence to a final torque of 70 lb-ft. Edelbrock recommends checking piston-to-valve, piston-to-head, and valve-to-bore clearances, and we found all of our measurements to be adequate. The Edelbrock instructions are very complete, and detail all of the issues you could encounter during installation. With the heads in place, we installed our Comp Pro-Magnum rocker arms and used a checking push rod to measure pushrod length. The Pro-Magnum rockers use ball/ball style pushrods, and ours measured 83⁄8 inches. After measuring, we ordered the Hi-Tech pushrods from Comp and got busy installing the intake, exhaust, and spark plugs on our engine.

Even though the E-Street heads use a spark plug angle of 15 degrees, they will work with most factory and aftermarket exhaust manifolds and headers. The tti headers we installed in a previous article offered plenty of clearance, and our factory replacement plug wires with 90 degree boots posed no installation issues. Remember that with aluminum heads, anti-seize compound must be used on the threads of the spark plugs to protect against dissimilar metal corrosion.

The Edelbrock heads require 14mm by ¾-inch reach reach spark plugs (long-reach), which are different than factory short-reach plugs, so you’ll have to buy new plugs when installing these heads. We picked up a set of Autolite 3924 plugs at the local auto parts store for our application. Remember that spark plug heat range requirements depend on the cylinder pressure of the engine, and the general rule of thumb is the hotter the engine, the colder the plug. Our engine isn’t all that hot with just over 9:1 compression, so we chose spark plugs on the colder end of the range.

After installing our pushrods and setting valve lash at zero plus one turn for our hydraulic lifter application, we topped our heads with a set of Edelbrock’s stamped steel, logo valve covers for a clean look. With the installation complete, we turned the key and fired up the 383 to check for leaks. Our engine ran great and seemed crisper when we opened the throttle, so we were eager to see what kind of improvement the E-Street heads would net. Our preliminary test drive was encouraging, and we could definitely tell that the 383 in our Chrysler was making more power and torque. With no problems after a local test drive, we took the big Chrysler over to our shop in Tampa, Florida, to strap it onto the Dynojet chassis dyno.

Installing new parts on your Mopar is great, especially when you can feel the difference in the seat of your pants. Taking your car or truck to the track is a fun way to track performance improvements as well, but the best way to measure how much power and torque your engine is making is on an engine or chassis dyno. Engine dyno’s are an excellent way to measure the true, unrestricted horsepower and torque that an engine makes without the parasitic drag of engine accessories or a drive train, but a chassis dyno measures the true power that is transferred to the rear wheels of the vehicle.