Zoomie392 Header Set, Chrysler-Imperial 392 Hemi Engine

Dimensions

Zoomie Length

Most Zoomie headers are offered in two lengths, either a standard 16″ (40.64 cm) or a longer 19″ (48.26 cm). (Big block Chevy Zoomie headers are a specific style and only one length). It is relatively easy to determine the length needed for the application. To be clear, 99% of all applications will use the standard 16″ length. The longer 19″ version requires a much higher chassis or engine location to allow necessary ground clearance.

To provide a simple example, the header should not hang down below the bottom of the wheel. However, this will vary depending on the wheel and tire profile. In the graphic below, a low-profile tire provides less ground clearance; therefore, the bottom of the header should maintain a higher value from the ground.

Many like to have that scraping-the-ground look on their street rods. However, that sort of look is best suited for trailered show vehicles and not those expected to travel city streets, including driveways, v-drains or dips, speed bumps, or other hazards that could damage the Zoomie header set.

Baffle Installation

Zoomie and Chopster Header Baffle Inserts:

Due to possible liability issues, Sanderson does NOT provide mounting holes for mounting the muffler baffle inserts. The customer or installer is responsible for the safe installation and proper securing of the insert.

Baffle Installation Procedure:

1. First, make sure the inserts are the correct size for the application. Sanderson’s 1.875″ (1-7/8″) inserts are for small block engine applications, and the 2.250″ (2-1/4″) inserts are for big block engine applications.
2. For NEW installations – Notice that one end of each Sanderson muffler insert is partly closed off with a welded washer.
3. Use a tape measure to determine the depth of the insert from the end of the tube. Use that measurement to mark the inside of the header tube. The insert depth should be held up slightly from the short-side radius at the lower bend and not bottom out (see image below). Measure the insert depth for every tube.
4. Insert the muffler into one of the header pipes with the partially closed-off end first. DO NOT FORCE. The insert should be snug but not too tight.
5. There are various methods to secure the insert. Either drill a hole slightly in front of the insert and install a stove bolt and locknut (or use red Loctite), or drill and tap directly into the baffle ring, using an appropriately sized bolt with a small amount of red Loctite on the bolt threads
   1. NOTE: Some customers have used sheet metal or self-drilling/tapping screws to hold the mufflers in place, but such screws tend to vibrate loose.
6. When the mufflers are securely fitted in all eight pipes, the headers are ready to install on the engine.

Hemi Engine History

It is crucial for us to know which Hemi engine is in your vehicle because there is more than one. (Sam of Century Performance Center, Inc provides this article.)

First, Some History:

Although Chrysler trademarked the term “Hemi” somewhere in the 1950s, it wasn’t until the second generation Hemi, the 426 that showed up in 1964, that Chrysler started using the Hemi term to officially define the name. The name originates from the hemispherical cylinder head and, more specifically, the combustion chamber design. The 426 Hemi, often referred to as the “elephant,” became well-known quickly for its use in NASCAR and a few special production vehicle applications. The trademarked name was not officially recognized from a commerce standpoint until February of 1966, 2 years after virtually everyone knew something about it.

However, while most people immediately recognize the term “426 Hemi”, it was not the first Hemi engine. The Chrysler FirePower (not yet coined as a Hemi) 331 V8 was the first to find itself between the fenders of a few 1951 model year vehicles. And there were others … which gets us here.

Each Hemi engine group uses a different exhaust port and bolt spacing. Therefore, Sanderson Headers for the Hemi engines vary slightly to include specific port and bolt layout flanges and varying primary tube bend radiuses to accommodate different exhaust port exit angles. Here are the four Hemi engine groups for which Sanderson builds headers. You will see in the list below that the Dodge and Desoto Hemi engines include a dimension. This is the easiest way to determine the difference between those two engine groups. Please refer to the graphics below the list to explain this dimension.

NOTE: Sanderson does not offer header sets for late model 5.7L, 6.1L, 6.2L, and 6.4L engines.

• Chrysler 426 Hemi
• Chrysler/Imperial FirePower  331-392 (331, 354, 392)
• Dodge 241-325  (14-3/8″)  (241, 270, 315, 325)
• DeSoto 276-345 (14-3/4″) (276, 291, 330, 345)

This first graphic shows the 14-3/8″ spacing for Dodge Hemi engines.

This second graphic shows the 14-3/4″ dimension of the DeSoto Hemi engines.

If you have any questions regarding the proper engine group or flange selection, please contact us by phone or through our Helpdesk.