Some say the air cleaner of an engine is like the front door of a house. That is, it’s what you see first and foremost. And the home owner can use that door to make a statement about the house without anyone seeing what’s inside. Much like what an air cleaner says about an engine without knowing what sits under it? Cylinder heads and head bolts may have a dramatic impact on the performance of an engine but do they work like the front door in setting the visual impression for the viewer?
Well, sort of. These days so many aftermarket heads have also become part of the ‘eye candy’ of a good looking engine but the head bolts are sort of the unsung hero holding everything together behind the scenes. It just happens to work out that way when we see a set of heads before they get bolted onto a block and go to work making big power. Yep, new heads are just plain sexy!
That works just fine with the fact that aftermarket heads are an industry that’s in constant motion – and that’s a good thing. It seems like someone is always coming out with a new version of an old head. With the rapidly advancing technology of design, production, machining and materials, parts are coming out faster, better and in some cases, even less expensive than ever before.
In some cases, the aftermarket heads are doing things you could never even dream about doing with the original OEM heads. So why not throw on a new set of heads on that motor you’re building? And don’t forget some new head bolts or studs to go with it. Why not, indeed. We rounded up the latest heads and listed them and their features here so engine builders can keep ahead of this fast-moving train.
Proving the Chevrolet Big Block is far from old, we have over half a dozen versions of BBC heads from some of the biggest names in aftermarket parts.
Brodix starts off their new cylinder head offerings with the SR20 that raises the bar in aluminum BBC heads. They are 100% CNC-ported and feature copper exhaust seats and ductile iron intake seats as well as .500? raised 440 cc intake ports with 2.400? intake valves. The SR20 flows at an incredible 507 cfm with the exhaust port flowing 335 cfm through a 1.800? valve.
The newly designed combustion chambers are 95 cc and the intake valve angle has been rolled to 20 degrees. The SR20 is radical enough to require the use of pistons, valve covers, head studs, shaft rockers and intake manifold that are specially designed for these heads. Tracy Dennis of Sunset RaceCraft Racing Engines said, “The SR 20 is going to change the sportsman racing market; it already has.”
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Dart Machinery is also offering a new aluminum head for big block Chevys called the 14° BC Pro1 head. It’s an as-cast head that requires no porting. Engine builders can use this head for Super Gas, Super Comp or bracket race engines. It also works great in the marine industry. Dart uses RMR Alloy for all their aluminum cylinder heads and block castings. The two part numbers are 18465030 – 14° BC Pro1 2.400/1.900 for the bare head and 18465136 – 14° BC Pro1 2.400/ 1.900/ 1.625D for the assembled head with titanium retainers.
Edelbrock is offering their new aluminum heads for Big Block Chevy motors with high compression. They’re called Performer RPM 454-O High Compression and come in three part numbers. 60429 are bare heads, 60439 are complete with valve springs designed for use with hydraulic flat tappet camshafts and 60435 comes complete with valve springs designed for use with hydraulic roller camshafts. These heads feature a 100cc chamber that is ideal for high-compression applications with both the intake and exhaust ports having been profiled for improved air flow.
The unique oval intake port shape produces flow similar to rectangular ports, but the smaller port size provides excellent seat-of-the-pants performance and crisp throttle response. They also have smaller-than-stock 11/32? valve stems for excellent flow and a lighter weight valve. They are available with two spring options, giving builders the option of choosing the right cylinder head for their engine package. Edelbrock told us, “In 2012, we decided to offer many of our popular cylinder heads with two valve spring packages.
This allows the consumer to choose the cylinder head spring package that is best for their application. The right spring that is matched to the camshaft will make for a smoother transition and increased valvetrain stability at high rpm, making the cylinder head more efficient.”
EngineQuest is offering their new 454 big block GM and 502 GM heads. The 454 GM is available in two runner sizes: 320 and 360 cc and is geared towards performance street and marine. These 454 heads are capable of being used on 1000 HP engines and come in 2.250 intakes and 2.30 intakes for the 320 and 360 runners accordingly. What sets them apart is they are 24 degree style. They rolled the head over two degrees from the stock 26 degree version GM made.
Those two degrees allow for a tremendous flow advantage. They also are equipped with bronze guides. Part numbers are Ch454a for the 320 intake runner with 2.250 intakes and Ch454b for the 360 intake runner with a huge 2.300? intake valve. EngineQuest also offers a head for the GM 502. It’s for Gen 5/6 and is mainly for marine use. While mostly for marine, the Ch502a can be used for the street. The part number is Ch502a for the stock style 502 GM with a 298cc runner and stock diameter intake. EngineQuest makes head bolts for all of these heads.