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Replacing the stock exhaust system on a 1968 small-block Corvette

Scavenging Expedition: Get perfect, spot-on fit from Corvette Central’s Deluxe exhaust system for C3 Vettes

Jim Smart Mar 6, 2018
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What is it about exhaust system replacement that leaves us befuddled? We get uptight because good, methodical exhaust shops are hard to find. Exhaust shops are generally short on attention to detail, which is frustrating—especially if we’re building a show car. The average exhaust shop isn’t going to give your Corvette the exacting attention to detail required in either a concours restoration or a restomod show car project.

Corvette Central can help with show quality OEM-style exhaust systems and parts for C1, C2 and C3 Corvettes. We’re talking perfect fit, drop-in replacement systems that are on par with what GM was installing on new Corvettes at the St. Louis assembly plant a 50 years ago. No grief. No hassle. Perfect fit.

We’re restoring a 1968 Corvette roadster at Hot Rods by Dean in Phoenix. Hot Rods by Dean has built some of the most incredible hot rods and muscle cars in the world. Our C3 1968 Corvette is among the easier restoration projects these professionals have ever tackled. Hot Rods by Dean is going to show you how to perform a complete exhaust system installation in your home garage.

Hot Rods by Dean has opted to replace the exhaust insulation blanket, too, which is also available from Corvette Central and is easy to install. It is critical to use the exhaust blanket in order to keep excessive heat and noise out of the cabin. If you’re building a restomod where authenticity isn’t important you may opt for any number of insulation and sound deadening kits available from Corvette Central.

The most important thing to remember about C3 restoration is how to infuse cool hidden modifications that will improve your driving experience. Classic looks on the outside complemented with hidden improvements that will enhance the relationship you have with your classic Corvette. Vette

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1. Corvette Central makes exhaust shops obsolete with complete exhaust systems and parts for 1968-’82 (C3) Corvettes. We’ve opted for a stock bolt-together exhaust system with all the hardware and hangers. Hot Rods by Dean is going to take the Corvette Central system and apply professional installation techniques that are crucial to a restoration.

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2. This is the center exhaust bracket (PN 323078) from Corvette Central. We like the close OEM-style attention to detail shown here.

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3. The exhaust hangers use authentic details to mimic the nuances of the factory pieces.

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4. This is the exhaust manifold heat riser, which allows hot exhaust gasses to flow to the intake manifold for a quick warm-up. Most of the originals have seized up from rust and corrosion. The Corvette Central heat riser offers increased freedom of movement.

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5. These exhaust tips (PN 328185) from Corvette Central are 100 percent stainless steel and are the last items you need to install.

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6. You do have choice when it comes to exhaust systems from Corvette Central. These are stock OEM replacement mufflers, which offer perfect fit. Corvette Central offers a variety of C3 exhaust system options, from dead stock to throaty aftermarket.

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7. We like these reproduction cast-iron ram’s-horn exhaust manifolds for the 350ci small-block. They offer an authentic demeanor and perfect fit. We’ve plugged the air injection ports for this particular application because we’re not running a smog pump. You can have these exhaust manifolds ceramic coated, which will keep them looking like new.

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8. Our reproduction cast-iron exhaust manifolds are bolted to the engine and are ready for the rest of the exhaust system. It’s nice working with new hardware void of corrosion and damage. What’s more, these are mighty authentic castings as far as reproductions go.

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9. The new heat riser assembly is installed prior to the extension pipe. Once you have your C3 up and running don’t forget to occasionally spray the heat riser shafts with penetrating lube to keep the butterfly free.

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10. Here’s another look at the reproduction exhaust manifolds provided by Corvette Central. These are really nice reproductions right down to the casting numbers and markings.

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11. This adapter insert is fitted into the exhaust pipe as shown. When installed, it will penetrate the pipe for a permanent fit. The adapter is needed because we’re going from a 2-inch pipe at the manifold to a 2 1/2-inch exhaust system all the way to the rear.

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12. We’re using a brass hammer to seat the adapter. Brass is softer than steel, which means we drive the adapter into the pipe without damage. If you use a steel hammer, you will damage the adapter.

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13. The exhaust pipes are fitted to the exhaust manifolds like this. Secure the nuts and flat washers, but do not fully tighten them yet. You want pipe flexibility for adjustment as you make your way back through the exhaust system.

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14. Here’s the driver-side where the exhaust pipe joins a new exhaust manifold. Corvette Central’s hefty 14-gauge (0.070-inch) wall aluminized tubing outlasts standard steel tubing by 2:1. How’s that for durability?

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15. The exhaust pipes are grounded via this ground strap at the first pipe union.

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16. Because the pipes are properly sized with slip-fit joints, they fit together with ease. You want the pipes fit to where there are no gaps. Gaps cause an annoying hiss and flutter, not to mention dangerous exhaust gas leakage. You may apply high-temperature exhaust sealer at these joints prior to joining, which will eliminate any risk of leakage. One other option is to weld these pipes together once they are joined and properly adjusted. The entire system must be properly adjusted prior to any welding.

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17. This dicey transition through the crossmember has to be undertaken carefully. Any pipe contact with the chassis will transmit engine harmonics and will drive you crazy.

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18. The tailpipe/muffler exhaust hangers install only one way so there’s virtually no way to mess this step up.

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19. The mufflers are positioned and installed as shown. Install them loosely until you get the entire system positioned.

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20. Each muffler is lined up with the hanger and positioned. Now is the time to go through the entire system and ascertain correct pipe clearances and position. You want at least a 1/2-inch between the pipes/mufflers and the chassis. Make allowances for movement during vehicle motion.

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21. Your Corvette Central mufflers should hang as shown.

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22. The muffler-to-pipe unions should look like this with the U-bolts positioned so the threaded tips point down.

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23. Where the pipes transition through the chassis, make sure you have plenty of clearance around them.

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24. Our nearly complete exhaust system installation looks like this, with plenty of clearance among the pipes, mufflers and chassis. All we have left to install are the stainless tips.

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25. Check out the fit here. The mufflers clear the body nicely, and at the proper angle relevant to the quarter-panel. Once you have ascertained exhaust system positioning, tighten all the fasteners and clamps firmly.

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26. We like these stainless tips from Corvette Central. They’re easy to install and they accent the Corvette’s aero-smooth rear fascia. Use the provided clamps to secure these tips to the mufflers.

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27. This is the foil and fiberglass transmission tunnel insulation blanket (PN 533565) for 1968-’75 Corvettes, which installs in the transmission tunnel to keep destructive and miserable heat out of your Corvette’s interior. You can take your heat/sound insulation even further with additional insulation options from Corvette Central.

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28. Here’s the transmission tunnel insulation blanket installed. You’re going to need the installation rivets (PN 532015) or the complete insulation retainer and rivets kit (PN 532566) to complete the installation.

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29. This is the 1968-’69 underbody insulation blanket (PN183010), which is installed next.

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30. Hot Rods by Dean installs the complete transmission tunnel and underbody insulation blankets. You must have the complete retainer and rivet kit to complete the installation.

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31. Both the transmission tunnel and underbody insulation pads are installed and should look something like this. We obviously performed this installation before the engine and transmission, and exhaust, were installed.

Photos by Brian Brennan

Sources

Hot Rods By Dean
Phoenix, AZ 85027
623-581-1932
www.hotrodsbydean.com
Corvette Central
Sawyer, MI 49125
800-345-4122
www.corvettecentral.com

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