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Holley Frequently Asked Questions

QUESTION Why do some header tubes have dents in them?
ANSWER Some tubes are dented at the factory for clearance around critical underhood components including spark plugs, power steering pumps, etc. If the dent is covered with paint or metallic ceramic thermal barrier coating it is supposed to be there.
QUESTION What is the difference between your Super Competition and Competition Headers?
ANSWER Hooker Super Competition headers are built from lightweight 18 gauge mild steel tubing with “tuned” lengths for maximum performance. Super Competition headers also use long transition collectors for reduced backpressure and increased exhaust flow. 5/16” machined flanges with welded O-rings make for a perfect sealing surface. Super Competition headers come with many different options in tube diameter and length for a particular application. Super Competition headers are the “World’s Best Header”. Competition Headers are built from durable 16 gauge mild steel tubing. Competition headers use long transition collectors for reduced backpressure and increased exhaust flow. 5/16” machined flanges with welded O-rings make for a perfect sealing surface. By removing some of the constraints on our designers when they design a Super Competition header, we can produce a Competition header for easier installation and a lower price. The Comp header will weigh slightly more than the Super Competition header but will last slightly longer under extreme climatic conditions. Competition headers are the “World’s Second Best Header”. We will sometimes spend two to three times more just to make a Super Competition Header work only five to ten percent better.
QUESTION How thick are your flanges and are thicker flanges better?
ANSWER “Not necessarily. A good flange seal can be provided through various flange thickness and tube/flange interface configurations when properly executed. Hooker header applications manufactured with a raised sealing bead are generally made with 5/16” minimum thickness flanges that are milled flat after welding to provide the designed sealing mechanism. Other header manufacturers simply run their flanges over a belt sander or body grinder, which is a far less accurate method of surfacing. Depending on the application, Hooker also builds various headers that do not use a raised-bead sealing mechanism. These applications incorporate the use of alternative construction methods that normally utilize 3/8” minimum thickness flanges, or thicker. All methods used by Hooker are designed to achieve a proper seal when installed as per the instructions.”
QUESTION Will your headers fit with aftermarket cylinder heads?
ANSWER Most aftermarket cylinder head manufacturers offer stock replacement and racing heads. Hooker headers will accommodate the stock replacement head in most cases. If the aftermarket head uses an angle plug configuration, the Hooker header for that application will have footnote 62 which says that it will fit with angle plug heads. If your aftermarket head is a straight plug stock replacement, the Hooker header for your application will fit. Most aftermarket racing heads have raised exhaust ports. Most Hooker headers are designed around the stock port height and will not accommodate the raised port heads. Hooker will produce headers for raised port heads when that particular head becomes the standard (for example: Super Competition header #6225 fits 1979-93 Mustangs with the popular TFS Twisted Wedge Race Head).
QUESTION Will your headers fit with my other performance equipment?
ANSWER In most cases, Hooker headers are developed around the stock engine location using stock equipment. Aftermarket products such as rigid motor mounts locate the motor in a different location causing possible fitment problems. Other performance products such as kickout style oil pans and performance “mini starters” can interfere with some header applications. Check the listing (read the footnotes) in our full line catalog or contact our tech department at (270)781-9741.
QUESTION What tube size do I need? Is bigger better?
ANSWER Header primary tube sizes vary on many factors: engine combination, transmission type, gear ratio and intended use of the vehicle. For example a truck header will be designed using longer length and smaller diameter primary tubes to enhance low to mid-range performance, where a header for a Pro Stock race car will have larger primary tubes and large collectors for the highest flow available. Bigger generally is not better when it comes to street driven cars. when you put too large of a header or exhaust on a street driven vehicle, you usually notice a severe drop in low to mid-range performance due to a lack of backpressure. To combat this issue, Hooker sometimes builds 3 or 4 different headers for a particular application with varying tube and collector sizes.
QUESTION Should I use exhaust wrap on my Hooker Headers?
ANSWER If your vehicle is being run on the street or for extended periods of time, you should never wrap headers. We never recommend exhaust wraps because it insulates the exhaust too much and retains moisture. This causes the exhaust temperature to be raised to a level that fatigues the header material causing cracks and can also cause rusting and pitting due to the moisture retained. .If you choose to use an exhaust wrap, the warranty will be void. If under hood temperatures are an issue, we recommend using Hooker’s Metallic Ceramic Thermal Barrier Coating. Our coating is applied inside and out. It is corrosion and heat resistant up to 1600°F. It also reduces underhood temperatures and has a polished high luster finish. Holding exhaust temperatures inside the header increases the exhaust gas velocity producing more horsepower. You can purchase any Hooker header with our Metallic Ceramic Thermal Barrier Coating by adding a -1 to the end of the part number.
QUESTION How thick are the tubes used in Hooker or Flowtech Headers?
ANSWER Hooker Super Competition headers use 18-gauge tubing, Hooker Competition Headers and Flowtech Headers use 16-gauge tubing and all shorty type headers use 16-gauge tubing.
QUESTION How do I know if my heads for a small block Chevy are factory dimensions?
ANSWER There are many aftermarket heads out there. Most offer a "stock" configuration head. One of the best ways to tell is to measure the distance between the spark plugs. The factory head had a 4.5" dimension between each spark plug. The stock head also uses straight spark plug exit not angled. Pay close attention to the information supplied by your head brand of choice.

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