Slant Six Racing

Slant six racing

A very good resource on slant six racing is provided by slantsix.org. They have a series of slant six newsletters with tons of information, not to mention the largest collection of Valiant information outside of valiant.org.

Also check out Allpar’s Hyper-Pak page.

Truckee's newsletter suggested that the renaissance of slant six racing began at Bristol in 1997, when 12 slant six powered cars were racing together in the same place. The Truckee webmaster and Doug Dutra had come in to cover the event (Doug Dutra works with the Slant Six News, and according to Truckee developed a reproduction Hyper-Pak manifold). Jack Poehler has also written about racing in the Slant Six News.

One interesting aspect of the slant six is that it was originally developed as a performance engine, and was used for drag racing for a brief time. When it was new, it was hot. That was before the 225 slant six, with its very long stroke, came in and traded torque for high-revving horsepower. The original 170 cubic inch version was, oddly, reported to be the easiest to adapt to racing, because it could rev high.

Ben wrote: “JC Whitney is offering a four barrel intake manifold for the slant six, made by Offenhauser.”

Mopar's own Web site refers to the Hyper-Pak:

The Hyper Pak used a long runner, 4-barrel intake package, which is almost impossible to find today.

The aftermarket version of this intake manifold is a short runner 4-barrel. It should only be used in racing applications. What you would like [for the street] is the large runner, aluminum 2-barrel intake (P4529115). This manifold is no longer sold by Mopar Performance. However, it was sold for 10 to 15 years. So if you can find one, it is worth the investment.

The small 4-barrel carbs that are available today are much too large for 225 cubic inches, so you want to stay with a 2-barrel carb with 350 cfm or less. The production engines typically used a 1-barrel carb. The production cam was very small, so upgrade to a mechanical cam (P4120243) which has 244 degrees duration and .436" lift.

All of the production heads used 1.50" intake valves and 1.36” exhaust valves. The hot tip in the old days was to cut down 392 Hemi valves for high-performance applications, but that is no longer required. Use 1.70" intake valves (P4286785) and 1.44" exhaust valves (P4286786) — both are stainless.

 

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