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What has sustained bracket racing for so long i...
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Some manufacturers like Edlebrock have enlisted v...
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RHS offers its Pro Action cylinder heads in three...
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A Closer Look at BBC Bracket Racing Cylinder Heads
Bracket racing has been around for about 35 years and in the beginning not many drag racing sanctioning bodies took it seriously, even though they had been essentially handicapping cars by their elapsed times in the eliminator categories for years. But having an entire event run with bracket cars was deemed as something sure to fail.
By Len Emanuelson
However, it proved to be just the opposite sportsman racers loved it and it allowed local drag racing to thrive and grow.
Back in its infancy, I covered weekly bracket racing in Southern California at the now defunct Irwindale and Orange County International Raceways. The action was hot and heavy with full fields of “Quick 32” cars and a couple hundred other cars competing in slower brackets. I even ventured back to Byron Dragway in Byron, IL for the first big $5,000-to-win and later $10,000-to-win events.
Bracket racing has come a long way since then with sophisticated electronics controlling throttle stops, delay boxes and anything else that will help give the driver a perfect reaction time to the starting lights, and to run as close to his dial-in elapse time as possible without going too quick and breaking out.
What has sustained bracket racing for so long is that a racer can build what he wants, unrestrained by rules or a class system. You can race a door car, altered, dragster, whatever as long as it meets the safety requirements for that association or track. You can also build the car that fits your budget and tastes. The light car/big engine combination can be fast, yet not break the bank. A heavy car/small engine combo might offer the consistency to put you in the winner’s circle week after week.
The key to any race engine combination is the cylinder heads. And what is available today in the aftermarket makes building a fast and competitive race engine relatively simple. The old days of grinding the ports on a set of iron heads, running to the flow bench, and then back to grind some more, are gone. Pro engine builders will always experiment to find that little edge in airflow, but for a bracket engine it is a waste of time and money and to be quite honest, these new heads are so good out of the box, most people will just screw them up by grinding on them. The real truth is that a set of state-of-the-art CNC ported heads will be at least a 100 hp better than the best ported iron production heads.
The plan was for this article to cover all bracket race cylinder heads but that quickly grew out of hand. And much of what we are discussing applies to all aftermarket cylinder heads; however, for the sake of focus we will cover more specifically what is new in the big-block Chevy (BBC) market. BBCs make up a huge part of the bracket engine business and are the focus of just about every cylinder head manufacturer. What started out as a canted valve 24-degree production head at GM in 1965 has morphed into mutations with half the valve angle, symmetrical ports and countless other changes and improvements. The choices are nearly endless with manufacturers like Brodix offering approximately 38 different BBC heads for sale. Armed with a little research you can find exactly what your customer’s engine needs to go to the winner’s circle.
Today’s aftermarket heads offer the engine builder a lot of advantages. Most serious bracket racers put 200-400 passes per year on their engines. Down south you can run three or more money races per week when the weather is good, and that racks up lot of run time. The durability factor for these aluminum aftermarket heads is 10-fold right out of the box. A big leap forward in materials such as virgin and super clean alloys used in the casting process (making them easy to weld for repair), heat treating, super thick deck surfaces and seats and guides put in place as only CNC machines can do it. You’ve got 5-axis CNC porting machines that can blend areas the human eye and hand cannot. Plus most heads have hardened or copper alloy seats and bronze valve guides.
One of the terms that may confuse some engine builders not up on the latest BBC terminology is that most heads are referred to by intake valve angle. Like we mentioned, Chevrolet designed the BBC with a 24-degree intake valve angle. The current practice in the performance aftermarket is to “roll” the cylinder head to a flatter intake valve angle with the extreme being Dart’s new 11-degree Big Chief and Pro-Filer’s 12-degree spread port head. When you roll the head in this manner two favorable things happen you raise the intake ports and the combustion chamber gets smaller both having a positive effect on power.
Another reason to abandon production heads is that they simply cannot feed the really large displacement engines that are common today. Even the dragsters are going big 509s, 555s. 572s, 632s are “meat and potato” engines with 700cid-plus becoming more commonplace. It takes port volumes in the 360cc to 420cc range, bigger valves bordering on 2.500˝-diameter and straight ports to handle these displacements.
For many years you could only find this kind of flow from a symmetrical port Pro Stock style head like the Big Chief and Big Duke. Now virtually every cylinder head manufacturer offers a conventional-style 24 degree head that will handle 1,100 hp, and is much easier on racer’s budgets because they do not require a special intake manifold, new headers and a dedicated shaft-rocker setup that when all tallied up could double the cost of the cylinder head upgrade.
Another factor dictating cylinder head selection is the march forward in cam profiles. It wasn’t long ago that a .750˝-lift cam was a really big cam. Pro Stock big-blocks are now running valve lifts in excess of 1.00˝ and valvespring pressures well above 1,000-pounds over-the-nose (valve fully open). Now hard-running bracket cars are running lifts and spring pressures never dreamed of a couple of years ago, and certainly more lift and pressure than an OE cylinder head can handle. These lifts and pressures require longer valves to prevent valvespring coil bind and a valvetrain and valvetrain mounting solution stout enough to open the valves without power-robbing deflection.
It’s worth mentioning that making your customer aware that stepping up to a good set of aftermarket cylinder heads is just part of the solution a rock-solid shaft-type rocker system is a must to get the most out of these modern designs, and also protect your investment and engine against damage. Establishing correct rocker geometry means that you need to move the rocker to the proper height and pivot location and you just don’t have that option with a stud-type rocker.
So let’s look at what’s available to make your customers go fast and keep the engine intact, run after run.
Air Flow Research
With nine conventional 24-degree BBC cylinder heads in its lineup, Air Flow Research is another one of those companies that can meet just about any BBC racer’s needs. Several oval port versions for heavy door cars are available and a trio of heads (345cc, 357cc and 375cc) focused on the really big motors. With more than 440 cfm flow for the largest port, AFR completes the package with .750˝-thick decks, slightly raised exhaust ports and low- and mid-lift numbers that ensure big power numbers.
Brodix has one of the most complete line of competition BBC heads available, and its Web site has a very precise selection guide that will allow you to choose the right cylinder head to optimize your engine combination. Brodix is one of several manufacturers who sell a top-end assemblies that include heads, manifold, valve covers, gaskets, sparkplugs and bolts which is a great idea because engine builders and racers often mismatch manifolds and cylinder heads, which costs power. Plus if you need these assembly components that when purchased separately really add up it becomes and even better deal.
Brodix offers both conventional 24-degree-style heads and 11-,14-, and 18-degree spread ports. Its Head Hunter and BB-4 and BB-5 series are conventional style heads that both offer huge flow numbers and advanced features such as rolled valve angles and raised intake ports (BB series). Brodix’s PB 1600 is a conventional port head with a 16-degree valve angle, It’s 416cc port flows a whopping 515 cfm and is suited well for a big-inch nitrous application.
Dart also offers top end kits with fully assembled heads, manifolds, valve covers and installation components. Dart’s top of the line heads include its Pro 1 CNC head that is available as-cast with a 275cc intake runner or 5-axis CNC ported with either a 335cc or 355cc runner. Its new Pro 2 cylinder head is intended for the larger displacement engines with a 380cc intake runner. Brass head bolt tubes allow room for these super-wide intake ports that would normally interfere with the head bolts.
These Pro Series heads also feature raised exhaust ports that improve flow on the exhaust side. Dart’s go-to head for bracket engines is the Dart 360 “Big M” that is available in a number of runner sizes. And while the Dart Big Chief has been outlawed from Pro Stock after winning three championships, it continues to get upgrades like different port shapes and valve angles. Dart will CNC port Big Chief heads to fit your engine combination.
Rick Roberts of Edelbrock Engineering made a good point in concluding that Edelbrock’s entire BBC cylinder head product line is appropriate for bracket racers. He even knows of a Super Gas competitor that uses Performer RPM street heads. It’s just a matter of how much power you need. And that holds true for almost every head manufacturer. Even and entry-level iron aftermarket head is superior to some 25-year-old iron heads that have been kicking around.
Edelbrock set out more than 10 years ago to build the ultimate 24-degree conventional port cylinder head. The Victor 24 is the result and will support engines in the 750-1,100 hp range and on 632 cid engines and larger. They are sold completely assembled in a variety of forms, and will handle camshafts with up to .880˝ lifts. If you are mounting and all-out effort Edelbrock’s Spread Port Big Victor CNC is good for 1,300 hp-plus on a 632 cid engine and is sold without hardware so the engine builder can specialize for the lift they desire.
Pro-Filer Performance Products
Pro-Filer has kept it simple by offering one basic 12-degree spread port design, but it has powered some of the quickest cars in the country. Available in two runner volumes (415cc and 470cc), Pro-Filer’s claim to fame is out-of-the-box performance. They flow 496 cfm @.900˝ lift and the extremely tiny 60cc combustion chamber allows for lighter pistons, more compression and improved combustion.
Patriot Freedom Series heads meet the demands of the BBC world, while keeping the quality high and the price reasonable. Patriot’s BBC heads are as-cast with a 320cc intake runner, bronze guides and a 5-angle grind. These heads come standard with a 119cc chamber. The company’s top of the line assembled heads come with 21-4N stainless 2.250˝/1.880˝ valves, .800˝ solid roller springs, titanium retainers, 7/16˝ studs, guide plates, machined locks, and Viton seals.
Race Flow Development
Curtis Boggs, Race Flow Development says they are very involved in the BBC market. “We have done about 5 years worth of engineering work together with Edelbrock to develop their conventional BBC casting. It’s currently the most powerful and fastest big block head. I know some others have claimed that about their heads as well, but typically on the track our cars are faster. Our shop car, Wayne Horton’s racer, runs about 6.85 or 6.90 flat constantly, and it’s a 598 cid BBC with a single 4-bbl cast intake and our conventional heads.”
Boggs points out that cylinder head design is much more complicated than producing a great flow number. The proper valve size, throat area, port area, short turn apex, air speed and wet flow all play a key role in how the head runs on the track as well as the efficiency of the port are all much more important.
RFD works with engine builders to custom-tune its heads to for drag racing applications, whether it's for a dragster or a door car. Boggs says they service many pro engine builders and specialize in producing custom port designs and “Private Label” CNC programs.
RFD has several cylinder head packages designed for specific applications, but most heads are custom designed. Boggs says they offer their own custom port designs for Dart, Brodlx, Edelbrock aftermarket heads including GM, Ford and Mopar factory heads.
Racing Head Service
RHS offers its competitive Pro Action rectangular port 24-degree-style head in both iron and aluminum. It comes in two sizes 320cc that will support 800hp-plus and 360cc that’s good for 1,000 hp. It is also available with full CNC porting in the Pro Elite series that kicks flow up over 400cfm. Again, it is a simple, but effective approach to making big power out of your bracket BBC.
Trick Flow is another company that has kept it simple by offering just two versions of its rectangular port 24-degree heads and a single oval port version. The race-breed rectangular port comes in both 360cc and 320cc runner configurations and is available with a spring package that will handle .850˝ lift cam. Trick Flow is a true value proposition with assembled heads costing less than some of its competitor’s bare castings.
Like Edelbrock, World products has many BBC cylinder heads that fit a good many race applications, but the head getting all of the attention is its new Merlin X. The head has been “rolled” to a 16-degree valve angle, but still accepts standard GM Mark IV intakes. World recommends new pistons to get the most out of the new tiny 90cc combustion chamber shape, and these heads were designed for a Jesel shaft rocker system. The mainstay for bracket racers using World Products has been the Merlin III that supports 800 hp as-cast and is available in a 310cc or 350cc intake port. With CNC porting option a 572 cid engine produced an additional 40 hp over an as-cast head.
There are many more cylinder head companies with innovative and quality products. Due to the limited space we have here we unfortunately didn’t get to write about their products in detail. However, do some research and you’ll be surprised at what’s available. The path to dependable big-block Chevy performance is well lit.
For information about these and other suppliers click on the Buyers Guide tab.