Go With the Flow

Gain More Power, Torque and Efficiency From Your C-10 Exhaust With Hedman Hedders

Remember how we were all taught the fundamentals back in grade school: times tables for math, phonics for reading, and even the four basic food groups for proper nutrition? I recall my high school auto shop teacher explaining the fundamentals of the four-cycle engine by likening it to the human body. He lectured that if you want to run faster, you’ll need more oxygen and food to power your body; or in the case of an automobile’s engine, more air and fuel. He expanded his theory to note that the lungs play a major role in our bodies’ performance, and he related their functioning to an engine’s exhaust system, which shares some similarities.

Most auto and truck manufacturers strive to make their engines profitable, yet reliable, offering value to their customers. When it comes to factory exhaust manifolds, function beats out form because an engineer’s only goal is fitment. This formula has worked well for the vast majority of truck owners, but it leaves others, people like you, yearning for more power.

So why are headers important, and if they’re so good, then why don’t they come on the truck from the factory. Let’s go back to the more air, more fuel and more power theory and focus on exhaust manifolds. Factory exhaust manifolds are so restrictive it’s like trying to run around your block while wearing a snorkel: It gets the job done, but requires a lot of effort. Tubular exhaust manifolds, or headers, open up the path so spent gasses can flow away from the engine more efficiently. The ultimate goal of a performance exhaust header system is to decrease flow resistance, or back-pressure, and to increase the volumetric efficiency of an engine, resulting in a gain in engine torque.

This idea dates back to the middle of the last centry when the pioneers of land speed records and straight-line drag racers were in search of more top end speed. Countless trial and error attempts were made before the science was perfected, and their research has shown that selecting the length and diameter of the primary tubes makes a lot of difference between improving and restricting power. For example, tubes that are too large will cause the exhaust gases to expand and slow down, thus decreasing the scavenging effect. Tubes that are too small will create exhaust flow resistance where the engine must work harder to expel the exhaust gas from the exhaust chamber, reducing power and leaving exhaust in the chamber to dilute the incoming intake charge. Since engines produce more exhaust gas at higher speeds, headers are tuned to a particular engine speed range according to their intended application. A good rule of thumb when choosing an application is that wide primary tubes offer the best gains in power and torque at higher engine speeds, while narrow tubes offer the best gains at lower speeds.

With that being said, the other thing to remember when selecting a set of headers for your truck is fitment. Take, for example, collector clearance: Anybody who has ever owned a lowered vehicle with a set of long tube headers knows to avoid speed bumps at all costs. Other things to consider are the length of the tubing: Many manufacturers of headers produce a variety of styles and lengths. Shortys, long tubes, and mid lengths all have their pro and cons, so which style is right for you?

We asked the same question and received some great answers from the professionals at Hedman Hedders, follow along with this install of a set on a mid-‘80s square-body Chevy equipped with a 383 small-block. Hedman offers a variety of headers and recently came out with a C-10-specific small-block Chevy header. More specifically, it’s a mid length model with lowered trucks in mind. The headers come in a variety of materials and finishes.

Sources:

Headman Performance Group
Hedman.com

PPC Customs
121 Sunnyside ste 201
Clovis, CA 93611
559.281.8484

Text by Marcel Venable
Photos Courtesy of PPC Customs

Here’s a look at Hedman’s standard-duty headers for the 1973-87 GM truck line equppied with a small-block Chevy engine. This pair came from the factory with an extremely durable, protective ceramic-metallic coating: HTC coating. Hedman Hedders pioneered the use of ceramic-metallic coatings back in the early-‘80s, and it’s now available in black, as well. Previously used exclusively in the aerospace industry, Hedman Hedders recognized its potential for improving the lifespan and functionality of exhaust headers.

Before installing the new headers, we removed the old exhaust manifolds and the starter motor plus we made sure that the cylinder head’s surface was clean where the headers will mount. If need be, spray gasket remover on the surface and let it soak in for a few minutes, then use a hard plastic scraper to remove the old gasket material. Finish cleaning the area with degreaser and steel wool.

To install the headers, place the truck on a set of sturdy jack stands high enough to insert the new parts underneath the truck.

Set the gasket to the header flange and push a header bolt though the flange and the gasket to hold it in place. If this gets a little tricky for you, loop a piece of electrical tape around the gasket and the header to hold the gasket in place until you get the bolts set in place loosely. Be sure to remove the tape once you get all of the bolts started.

To prevent future damage, such as a seized bolt, use an anti-seize paste on all of the bolts, especially when using aluminum cylinder heads.

Run in all of the bolts to the flange; start in the middle and work your way out toward the end.

Underneath the truck, you’ll need to cut some of the old exhaust tubing off to align it to each of the header collectors. This is a ball-style collector that allows some wiggle room in fitting the exhaust tubing while maintaining a leak-free seal without the use of a gasket.

A pair of tubing flanges is provided in the kit that must be welded to the exhaust tubing so that the collectors will mate with the rest of the exhaust.

Hedman prides itself on quality and fitment, as seen here in this photo of how well the headers fit in this engine compartment. Ease of fitment makes routing spark plug wires easy to manage, resulting in no burnt plug wires or any other obstructions.

Reinstall the starter motor, start the vehicle, and let it run up to operating temperature. Then turn off the engine and check the torque settings on the bolts with a torque wrench while they’re still hot. Tighten them accordingly and repeat this process until the bolts stay tight after the engine has warmed up. Then lower the truck back down and get out on the road to feel the torque gain that a set mid-length Hedman headers will give you for many years to come.