Dorman# 674-501
Replaces General Motors# 372243
Fits the Following Applications:
1980-69 Corvette 5.7L (350 CID), 1968-66 Corvette 5.4L (327 CID), 1957 Corvette 4.6L (283 CID), 1990-83 Medium Duty, School Bus 5.7L; LH & RH
See eBay Compatibility List for Fitment Data
Automotive Color / Finish: Unfinished
Automotive Item Type: Standard Replacement
Bolt Hole Quantity: 9
Engine Manufacturer: GM
Exhaust Manifold Compatibility: Not Applicable
Exhaust Manifold Inlet Port Shape: Round
Gasket or Seal Included: 1 Flange
Hardware Included: 6 Studs, 3 Nuts, 3 Washers
Material: Cast Iron
Package Contents: Exhaust Manifold, 1 Flange, 6 Studs, 3 Nuts, 3 Washers
Notes: Includes Gaskets and Hardware (where required); Right; wo/Square Bracket
Dorman Exhaust Manifold
More like a complete kit than a single part, many of our Exhaust Manifolds include gaskets and hardware for a complete installation. Since this part is a direct replacement, the exact fit adds another layer of efficiency and convenience.
- Includes heat-shield for protection of hoses, wiring, and other engine components
- Cast iron or stainless tubular construction protects against warping and/or cracking
- Leak-resistant for long-lasting performance
- A rigorous quality inspection has been undertaken to ensure that this part conforms to product standards
Search Keywords: Exhaust, Manifold, Manifolds
Alternate Names: Exhaust Header
Exhaust Manifold
Frequently Asked Questions
What is an Exhaust Manifold?
- Exhaust manifolds do many different jobs (depending on application):
- Transporting extremely hot exhaust gases (up to 1400 F) from the cylinder head to the exhaust piping.
- Providing mounting for Oxygen sensors, A.I.R. piping, and EGR piping.
- Sealing the engine head and exhaust piping to prevent fumes and noise from escaping the engine compartment.
Why do Exhaust Manifolds fail and what happens when they do?
- Exhaust Manifolds can fail for some of the same reasons as any other type of exhaust part. Heat, thermal stress, and corrosion can produce cracks that result in leaks and noise. When a manifold fails there is a pulsing noise ranging from a soft ticking to a loud booming depending on the size of the leak. The hot gases can burn nearby wires and hoses, causing additional damage. Additionally, carbon monoxide vapors may find their way into the passenger compartment with potentially deadly results. The Manifold must be replaced when it fails.
Reprinted from Dorman's Exhaust Manifold FAQ.
Exhaust Manifold Replacement Tips:
- Always compare the replacement unit to the original before installation.
- Always start with a cold engine. Removing exhaust bolts from a hot engine may damage the cylinder head threads.
- Clean mounting surfaces are required for all exhaust manifolds. See the shop manual for any warnings or special instructions for the vehicle application.
- Use caution when replacing exhaust manifolds on aluminum heads.
- Never reuse the exhaust manifold gaskets.
- Torque all bolts to manufacturer’s specification. See the shop manual for torque specifications and sequences.
- If the original exhaust manifold is cracked and/or has a blue color, check for a rich running engine or an ignition system failure. If this condition is not corrected, repeat failure will occur.
- For ease of installation, replace the catalytic converter and manifold as an assembly on the 1996-98 Honda Civic, especially with high miles.
- Be sure to reuse all brackets and braces. Failure to do so will result in premature failure.
- Prior to installing the oxygen sensor into the replacement manifold, inspect the Oxygen sensor threads for damage. Failure to do so will result in damaged threads on the replacement unit.
- Be sure to use anti-seize on the oxygen sensor threads to prevent galling of the threads.
Reprinted from Dorman's Exhaust Manifold "Technically Speaking" Bulletin.
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