Heat Seal

What’s New In Header And Exhaust Gaskets

Jeff Smith Sep 1, 2001 0 Comment(s)

Step By Step

There are several styles of header and collector gaskets available from a wealth of sources such as Mr Gasket, Fel-Pro, Earl’s, SCE, ROL, and others. The latest designs are the aluminum and embossed copper gaskets.

One of the more popular performance gaskets is the Fel-Pro perforated steel-core gasket also available for collectors. Fel-Pro offers 15 different header gaskets for the small-block Chevy alone.

Most performance gaskets come with slotted-end bolt holes to make installation easy.

SCE makes a slick embossed copper gasket with ridges that are designed to increase load pressure at the sealing ring to prevent leaks while maintaining bolt torque. These gaskets are available for small- and big-block Chevys and also for header collectors.

The Earl’s Pressure Master gaskets use an aluminum frame that encloses replaceable aerospace graphite foil seals.

These gaskets combine superior torque retention with a leak-proof seal. Earl’s offers six different gaskets for small-blocks and one for a big-block, with replaceable inserts for each.

There are also collector seals available.

There are several exhaust-port openings for a small-block. For proper sealing, make sure to use the gasket that matches the port and offers the most gasket surface.

ROL Gaskets offers both the standard fiber gaskets as well as a graphite wire-reinforced high-performance gasket for V-6 small- and big-block Chevys. The Hi-temp gasket has excellent heat-conduction characteristics that prevent localized hot spots (like around the center exhaust ports on a small-block) that can warp header flanges and create leaks.

Mr Gasket also offers a Copperseal 0.043-inch thick gasket for small- and big-block Chevys that come with header bolts that include lock washers for bolt retention. Mr Gasket also offers fiber material and Ultra-Seal graphite-impregnated gaskets with a perforated metal core.

Summit also offers copper header and collector gaskets for small-block and big-block Chevys.

ARP’s small 3/8-inch–head stainless steel bolts work well for headers because they can clear tight spots around header tubes at the flange. Stainless steel bolts can also be used on collectors to prevent corrosion.

Even the best wire-reinforced gasket will burn through if bolt torque loosens. You can tell a header or collector gasket is leaking by the carbon track on the gasket. Often, just retorquing the bolts will produce a leak-free seal.

Harry Truman once said, “If you can’t take the heat, stay out of the kitchen.” He could have been talking about either thin-skinned politicians or header gaskets. It’s hard to imagine a component that is heat stressed more than a header gasket. Exhaust-gas temperatures in excess of 1,300- to 1,500-degrees F are not uncommon, yet the gasket is required to withstand this heat blast several times a day for years. Is it any wonder that header gaskets blow out occasionally?

On the other hand, there are few things more aggravating than that ticking sound that gradually builds into a full-fledged leak, making your otherwise pristine Pro Touring Camaro sound more like a cantankerous Stanley Steamer. You could have all the trick parts in the world bolted to that Camaro, but with an exhaust leak, it has no more boulevard appeal than a ¼-million-mile ’74 Vega with two dead cylinders.

The best defense against those infuriating exhaust leaks is a great offense starting with quality gaskets. Like most things in life, you get what you pay for and those paper gaskets that come with most header sets are good for a month or two of operation before they surrender to heat and exhaust gas pressure. But those gaskets are not your only choice now that there’s a whole slew of slick header and collector gaskets. The latest versions are the aluminum and copper gaskets that are soft enough to conform to the header flange yet durable enough not to melt under that daily hot exhaust assault. But there’s more to this story than just new materials. There are several techniques and tricks you can employ to ensure that the header bolts stay tight, and the gaskets keep their place.

Torque Talk

The biggest challenge to sealing headers and collectors is keeping the gasket tight against the head. The most common problem with blown header gaskets isn’t the gasket itself, but the fact that the bolt loses its torque. While it may seem that the bolt loosens because of some occult combination of heat cycling and vibration, the truth is that the gasket compresses and this reduction in thickness causes the bolt to become loose.

This is a common problem with the conventional compressed-fiber-material gaskets. After the gasket is tightened and subjected to several heat cycles, the material compresses. This reduces the distance between the header flange and the head, which creates the same effect as loosening the bolts. Once bolt torque is lost, exhaust-gas pressure can push past the gasket. In a relatively short time, the hot exhaust gas can burn the gasket, creating the exhaust leak. Several years ago, numerous companies began making high-performance gaskets that were less compressible. The most common design is the wire- reinforced graphite-compound gasket made famous by Fel-Pro. These gaskets compress less than fiber-style gaskets due to their internal wire reinforcement, but it’s still a good idea to recheck bolt torque at least once. The graphite coating also prevents sticking and allows the gasket to move when the header heats up and expands.

The latest generation of gaskets are the copper or aluminum-frame gaskets. The aluminum gaskets rely on an internal graphite seal to prevent leakage. These seals can be replaced if they leak or become damaged so you don’t have to buy the frame in addition to the seals. There are several copper gaskets with SCE as the originator of the embossed copper header gasket that is designed to create a leakproof seal when the header is tightened down. There is a slight amount of crush built into the embossed area, and the ridge creates an increased clamping load without requiring increased bolt torque. Copper also does not suffer from the movement problems that can plague other gaskets. Even with all these advantages, it’s still a good idea to retorque any gasket after one or two heat cycles to ensure a solid, long-lasting seal.

As you can see, there’s much more to header and collector gaskets than just pulling them out of the package and bolting them on. There are plenty of different styles and prices to choose from. But regardless of which you choose, a little maintenance is required to make these gaskets live longer.

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