Photos by Dick DeLoach
Prepping a Set of Dart SS Heads
There are many ways to extract more horsepower out of an engine without resorting to massive internal modifications. By getting the most out of the induction system, an engine will work to its max. One piece of the induction system that many overlook is the heads and valve train. But it is these components that can have the largest effect on not only overall horsepower, but in what RPM ranges that power is produced.
That is why when the owner of this Chevy Nova wanted to get the most out of his engine, and had already installed an Edelbrock carb and Weiand intake manifold, he figured that the next logical step is to turn his attention to the heads and valve train. This vehicle has a 283 V-8 with mild RV cam, but other than that the engine is stock. Though small in displacement, the 283ci Chevy engine is a long-standing workhorse that is capable of producing surprising amounts of usable horses. While this won’t be a racecar, or even a daily driver, the owner still wants it streetable, so our goal is to pump up the power with components that don’t require constant tweaking and adjusting.
We started by establishing baseline numbers at Westech Performance (Mira Loma, California) on the SuperFlow AutoDyn chassis dyno. It was determined that the engine had one head gasket that needed replacing and the heads could use reconditioning at the very least. The valve seats and valve “poppets” (mushroom shaped ends) had some buildup, requiring grinding, and the springs were fatigued and needed replacing. It quickly became obvious that the best long-term solution was to replace the heads and valve assemblies all together.
We put in a call to Jack McInnis at Dart Machinery (Troy, Michigan), and after a brief discussion about our project, the engine size and our goals; he suggested we use a set of their new Dart Iron Eagle S/S cast iron heads (PN# 10021070), a vast improvement over factory originals that McInnis said should add about 35-to-40 more hp.
To give you a little background on Dart, Richard Maskin founded the company in 1981 in a two-car garage in Oak Park, Michigan, with a desk and a phone. Maskin soon turned his passion for drag racing into a thriving enterprise; eventually producing complete cylinder heads from scratch.
It wasn’t long before Maskin became well known to drag racing fans as a mechanical mastermind whose engines have won NHRA Pro Stock championships and dozens of national events. This hands-on experience laid the foundation for Dart Machinery, today a leader in aftermarket cylinder heads, intake manifolds and engine blocks. “Our engine program and our daily interaction with leading engine builders and winning racers keeps Dart on the leading edge of technology,” Maskin said. “We apply everything we learn to produce more powerful and more reliable parts for Dart customers.”
In recent years, Dart’s spread-port Big Chief heads have set the standard in classes ranging from Pro Street to Pro Mod. This tradition of innovation has continued with the introduction of affordable Iron Eagle S/S and PRO 1 cylinder heads for small- and big-block Chevy V-8 street/strip applications. “Iron eagle S/S heads are a great, economical performance upgrade for street cars, trucks and street/strip use,” McInnis said.
The heads feature thick port walls (extra meat for porting), enlarged water passages, multi-angle intake valve seats, hardened and radiused exhaust valve seats, bronze valve guides and heart-shaped 49, 64 or 72cc combustion chambers.
The heads can be purchased bare or fully assembled including stainless steel valves, valve springs, retainers, locks, seals, studs, and guide plates. They come with your choice of angled or straight plug locations and accept all early and late model accessory brackets. For our article we chose bare heads because we wanted to use valves and springs from a couple of other companies.
We arranged to have the head prep and valve work done at Clay Smith Engineering (Buena Park, California), a company well known for its high-performance and racing cams for more than 75 years and a distributor of Dart products since Dart began. “In the years I’ve worked Clay Smith I’ve found that Dart cast iron heads are among the cleanest castings we see,” head specialist Chad Langdon said. However, Langdon explained that they still have a prep, paint and machining procedure that they go through with every head they sell, which was great for us.
We followed the process to see how Langdon and machinist Evan Speilman do it. Check out the photos and you’ll find that prepping and assembling heads isn’t all that hard if you know the game plan.
Clay Smith Cams