Head Master Part 1

July 16th, 2010

Text by Dick DeLoach

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.

Sources:

Dart Heads

248.362.1188

www.dartheads.com

Clay Smith Cams

714.523.0530

www.claysmithcams.com

Manley Performance

800.526.1362

www.manleyperformance.com

Westech Performance

951.685.4767

www.westechperformance.com

1. The first step in revamping the 283 V-8 is replacing the heads with Dart Iron Eagle S/S cast iron heads. We’ll also add new chrome Dart valve covers when we install the heads.

2. Machinist Evan Speilman says the Dart heads have very clean castings, but he still de-burrs and cleans every head they sell.

3. Next the head is washed thoroughly with soap and water and then blasted dry with an air hose.

4. Then the top (valve train side) of the head is painted with Rust-Oleum metal primer.

5. With head turned over, the exhaust ports and head surface are carefully tapped off.

6. The exterior surfaces of the head are then painted gloss black and the head is ready for machining. (Note: the heads can also be machined then prepped.)

7. While Speilman was prepping one head for machining, head specialist Chad Langdon worked on the other head by honing the valve stem seals and the bronze valve guides to make certain they are concentric.

8. As you can see, a tiny bit of material is present after precision honing work.

9. The head is then placed in the resurfacing machine and adjusted to make sure it is perfectly level.

10. A carousel with rotating blades then moves across the surface of the head shaving it smooth to ensure the deck is perfect. The head is now ready to be assembled.

11. Langdon preps the Manley Performance valves by first painting the edges of the poppet end with bluing liquid. This is done to make sure the entire surface of the valve has been hit with the grinding wheel.

12. The valve is then placed in a seat grinding machine and the surface of the valve ground slightly.

13. The valve seats are then painted with bluing liquid in preparation for honing.

14. The valve seats are then honed using the proper grinding tip.

15. You can see that the bluing liquid has left a ring around the grinding tip, meaning the valve seat is concentric.

16. With the valves and seats ready, the valve stem guides and valves are lubricated and the valves are inserted into the block.

17. Next, the Clay Smith Cams Teflon valve cups and spring seats are installed over the valve stems.

18. Then the valve springs (pre-set to the proper pressure), spring retainers and split locks are installed, using a spring compressor.

19. The finished heads are ready to install. Stock airflow is in the 230-to-234–cfm range but it can be improved a bit with a valve job and some chamber work to achieve airflow in the 240-cfm range.

20. In addition to many different styles of valve covers, Dart also offers the Iron Eagle S/S head preassembled, as well as bare.

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