How long have you been an enthusiast of the Mopar brand? Has it been since the ’80s, ’70s, ’60s, or even earlier? If so, you remember the days when Mopar owners were treated like the red-headed step children of the automotive aftermarket (no offense to our readers who are actually red-headed step children, it’s just a saying). In fact, for many years Mopar owners had to deal with sluggish support when it came to high-quality performance parts for their cars and trucks, while off-brand owners enjoyed a plethora of support for their cars and engines. Times have changed, however, and now owners of Mopar big-block, small-block, and Hemi powered vehicles can purchase an abundance of performance parts to enhance the performance of their cars and trucks.

One of the biggest aftermarket supporters of the Mopar brand has to be Edelbrock Performance. Edelbrock was the first company to provide economically priced, great performing aluminum cylinder heads for Chrysler big-blocks and small-blocks, and we see more cars at events and races sporting Edelbrock Performer RPM heads than any other type of aftermarket head. Edelbrock also has a full line of intake manifolds, carburetors, and other performance goodies for Mopar engines, all of which can improve the power, performance, and looks of your ride. We know from our testing that the Performer RPM and Victor big-block heads can help achieve great power, so when Edelbrock introduced their E-Street line of heads for the big-block, we wanted to be the first to test them.

Edelbrock’s E-Street cylinder heads are designed as a bolt-on replacement head for non-emissions 1961-1978 Chrysler B and RB series big-block engines. The assembled E-Street heads are available in two different part numbers, 5090 and 5093 offering combustion chamber volumes of 75 and 84 cc’s respectively. Other than chamber volume, the specs for the E-Street heads are identical, with 210cc intake ports and 70cc exhaust ports, and swirl-polished stainless steel valves. Intake valves are 2.14-inch, and exhaust valves measure 1.81 inches, both with undercut stems for improved flow. Edelbrock installs their PN 5792 Sure-Seat valve springs on these cylinder heads, and the heads can handle camshafts with lifts up to .600 inch.

These cylinder heads are assembled with all new parts, including Edelbrock’s PN 9644 machined steel retainers, PN 9616 locks, and PN 9644 valve spring seats. Two-ring positive control oil seals are installed on the valve stems, and all of the provisions for the intake manifold, exhaust headers, rocker arms, and accessories are in the factory locations, for a true bolt-on installation. Additional benefits of the E-Street heads are dry, Heli-coiled exhaust bolt provisions, and spark plug provisions that are angled 15 degrees for more efficient combustion. The 383 we’re testing these heads on is equipped with a low compression ratio of only 8.37:1, so we decided to order the 75 cc chamber heads to increase the compression of our engine.

Compression ratio is an important factor when it comes to power, and with such low compression, the 383 in our Chrysler Newport isn’t what we’d consider a performance engine. We have already made improvements to our engine in previous articles, installing a Comp hydraulic flat-tappet camshaft and lifters, Comp double-roller timing chain and gears, Edelbrock Performer RPM intake, 750 cfm Edelbrock Performer series carburetor, and tti headers and exhaust. The details of these installations can be found in previous issues of Mopar Muscle, and netted improvements of some 33 horsepower and 27 lb-ft of torque at the rear wheels.

By replacing the factory 906 heads on our 383 with the E-Street aluminum heads, we’ll see several immediate benefits, including a 40-plus pound weight reduction from the front of our already heavy Chrysler convertible. Additionally, the smaller 75 cc combustion chamber will increase the compression of our .030 over 383 from 8.37:1 to 9.38:1, over a full point. 9.38:1 compression is still not what we’d consider high, but at least we’re going the right direction in terms of performance. The closed combustion chambers with angled spark plugs will also improve combustion efficiency, further adding to our engine’s performance potential.