Allard J2X With Ardun Heads on a Ford “Flathead” V8

In a previous post dated July 12, 2012 I was critical of the design of the Ford “flathead” engine.  Recently I saw an Allard J2X that had a Ford “flathead” V8 engine that had been fitted with Ardun heads.  Ardun heads are interesting on several levels.  These heads converted the Ford “flathead” V8 engine into a hemispherical combustion chamber overhead valve engine.

A cross section of a Ford “flathead” engine fitted with the Ardun head conversion is shown below:

 Ford “Flathead” V8 Engine Fitted With Ardun Heads (from C & T Automotive)

The addition of these heads to the Ford “flathead” engine increased the output of the 239 cubic inch engine from 100 horsepower to about 150 horsepower.  The Ardun heads were designed by the Ardun Mechanical Corporation of New York which was headed by Zora Arkus-Duntov and his brother, Yura.  Many of you might recognize the name of Zora Arkus-Duntov as the eventual Chief Engineer for the Chevrolet Corvette.

The Ardun Mechanical Corporation designed the Ardun head in 1947/1948.  But unfortunately the Ardun Mechanical Corporation went bankrupt in 1949.  Then in the early 1950s Zora Arkus-Duntov became involved with Sydney Allard, the developer of the Allard sports car.  Allard pioneered putting American V8 engines in smaller, lighter British sports cars.

The first Allard sports cars were fitted with the Ford “flathead” V8 engine.  Later Allard began to offer Ford V8 engines with the Ardun heads in the Allard J2 and J2X cars.  An example of an Allard J2X with the Ford “flathead” fitted with Ardun heads is shown below.

1953 Allard J2X With The Ford/Ardun V8

In 1953 Zoro Arkus-Duntov joined General Motors and was instrumental in getting General Motors to install their new V8 engine in the Corvette.  The Corvette has not looked back since.

Ardun Heads Mounted on the Ford “Flathead” V8 Block

Note the size of the Ardun heads on the Ford V8 engine.  This typical of “hemi” engines.  In hemispherical engines the spark plugs are mounted on top of the hemispherical combustion chamber with the intake and exhaust valves located each side of the spark plug.  With the angles of the intake and exhaust valves in a hemispherical combustion chamber the result is a large head size.  This arrangement and large head size is also very noticeable on all of the more famous Chrysler hemi engines.  With single camshaft engines this wide spacing of the intake and exhaust valves results in very large rocker arms. I think that engines with hemispherical combustion chambers are great candidates for dual overhead camshafts on each bank of cylinders.

The Allard J2X Is A Rather Small Sports Car

This particular Allard J2X is said to be the only Allard in the United States fitted with the Ardun heads.  As good as the Ardun heads were in improving the horsepower output of the 239 cubic inch Ford V8, the power output from these engines pales in comparision to some of the other engines that were also fitted in the Allards such as the Chrysler V8 engines with about 235 horsepower and the Cadillac V8 engines with about 250 horsepower.

This Allard Has Left-Hand Drive

The Allard cars are interesting as these were the first relatively successful cars that combined British car design with American V8 power eventually leading to the AC Cobra, Sunbeam Tiger, and the Jensen Interceptor cars, among others.

The Allard J2X Cars Were Widely Raced During the 1950s

See my post on March 9, 2013 about an Allard J2 with the 331 cubic inch Chrysler Hemi engine.

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7 Responses to Allard J2X With Ardun Heads on a Ford “Flathead” V8

  1. Al Halliday says:

    diff topic. New to engine rebuilds. I have stuck 1947 mercury 1 ton with 239 flathead. Have carburetor off and wondering how I can tell which valves are stuck? I poured diesel fuel down top of intake manifold and it came out 3 of 8 sparkplug holes. Any help would be appreciated , thanks Al from Nova Scotia Canada

  2. I was aware that there was an overhead conversion for the Ford flat head but had assumed that the conversion was accommodated by installing a pair of SHARP heads from a Southern California manufacturer. It’s obvious that ARDUN has solved that problem hands down but was there ever another solution?
    Thanks. Russ

  3. Pingback: History Reimagined: We test drive Hollywood Hot Rods' 1932 Ford – SILVAVLIS

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  5. Darren Perkins says:

    I am Having trouble locating tappet clearances for the Ardun alloy head conversion to ford flat top v8 if anyone could help me out !
    Thanks in advance!

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