Exploring Edelbrock’s New E-CNC Chevy Heads
He moved on to the California Institute of Technology (Caltech) to receive his PhD. Roberts cut his teeth at Air Flow Research where he came to know the late Ken Sperling and his wife, Phyllis. Sperling was a mentor and friend to Roberts, allowing him to practice and learn his craft. In 1991, Roberts joined Edelbrock where he has been ever since.
We asked Roberts about how the E-CNC cylinder head came to pass. “Like many projects this one was an evolution. We experimented 12 years ago with what I refer to as a factory angle milled head. During my days in a porting shop we routinely performed an angle mill operation to reduce the chamber size after extensive port and chamber grinding. It was a whole lot of work to correct the head bolt holes and intake face so everything would go together,” Roberts reflected.
“I got the idea to just ‘roll’ the deck of the head from the very start of machining rather than do it after the fact like we had to in the porting shop. Our first version was a big block Chevy and we rolled it 1 degree. The only problem with the head was the rolling operation dropped the height of the exhaust ports around 1/8-inch and caused some problems with the outboard short head bolts.”
We asked Roberts to expand on development of these heads, “Pat Musi came along with his 555 crate engine idea which was first built using our big bad race 24-degree head. The problem with that was that the exhaust ports were raised 0.531-inch over stock which made header fitment in the chassis of a door car a real pain. There were a lot of complaints. We then took our old rolled over head design and dusted it off. Since we were going full CNC it meant the exhaust height issue in the original head could be addressed. I decided to change the roll angle from 1 to 1.5 degrees and not only restored the original stock exhaust bolt height but raised over stock an additional 3/16-inch. I figured that would help exhaust flow performance without requiring custom headers in a door car.”
Roberts’ review of the overall E-CNC program is exceptional, “In the end we were delighted with the results. Here you have a good flowing fully CNC ported cylinder head compatible with off the shelf pistons, intake manifolds, rocker arm systems, and headers for a very reasonable price. The intake port ended up a little smaller than that on the race heads but gave up nothing in the final product and now does not require any kind of special exhaust system.” We learn from Rick Roberts development of these heads didn’t require much computer aid time because they’re an adaptation of castings that already existed.
E-CNC – Bang For The Buck
If you’re on a tight budget – and even if you are not, the E-CNC head is great bang for the buck for even the most modest of street engine projects because when you consider what it costs to take factory iron heads and massage them to spec, putting them on the shelf and opting for E-CNC is a no brainer.
Expect to spend on the order of $500 for a valve job with hardened seats, fresh guides, and new valves for those rusty old iron heads not including port, bowl, and chamber work. Bare, the E-CNC 185 head retails for $738.99 at Summit Racing Equipment. At the other end of the scale at Summit is the complete E-CNC 355 big-block rectangular port head for $1629.95.
The E-CNC cylinder head is assembled using manganese bronze valve guides, powdered metal interlocking valve seats, one-piece stainless steel valves with hardened tips, duty-designed valve springs, hardened spring cups, and 3/8-inch rocker arm studs for durability.
What you have on your side with the E-CNC is technology mostly with advanced combustion chambers and port design – air/fuel management that will net you more power than those stock iron heads ever could. And because they are A356 aluminum, they remove excess heat like an iron head never could.
E-CNC 185 Small-Block Chevy
- Intake Flow at .600-inch Lift: 254cfm
- Exhaust Flow at .600-inch Lift: 203cfm
- Chamber Size: 64cc
- Intake Runner Volume: 185cc
- Exhaust Runner Volume: 75cc
- Intake Valve Diameter: 2.02-inch
- Exhaust Valve Diameter: 1.60-inch
- Deck Thickness: 9/16-inch
- Valve Spring Diameter: 1.46-inch
- Maximum Valve Spring Lift: 0.575-inch
- Rocker Stud Diameter: 3/8-inch
- Push Rod Diameter: 5/16-inch
- Spark Plug: 14mm with 3/4-inch reach (Champion RC12YC)
Spring Pressure – You Need To Know
Two E-CNC heads are available for the small-block Chevy – one with springs for flat-tappet hydraulic cam and the other for roller hydraulics, which boils down to spring pressure. Otherwise – same castings. If you’re seeking a complete head, consider spring pressure in the process.
Though Edelbrock offers you one E-CNC small-block head with two different spring pressures, keep in mind valve springs must be cam profile, valvetrain weight, and rpm compatible.
Another factor is valvetrain weight. The lighter the valve, the less spring pressure needed. By the same token – the heavier the valve, the greater spring pressure should be. Roller tappets require greater spring pressure because roller lifters are heavier. The more valve train weight you have meaning valve, retainer, keepers, rocker arm, push rod, and lifter – greater spring pressure required.
Too much spring pressure will cause excessive wear. Not enough spring pressure will cause valve float at high rpm. Follow your cam manufacturer’s directions to the letter. When you order a camshaft, opt for a complete kit including valve springs.
What Does It All Mean?
Edelbrock continues to demonstrate to us it still has kept its corporate foot in street and strip performance and hasn’t let up on the throttle even in the toughest of economic times. Instead, it has kept its imagination at work developing exciting products enthusiasts want – and at a price enthusiasts can afford. That said, we will cop a pair of E-CNCs, please.