Re: Hemi 6
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Re: Hemi 6

Bob, it turned out to be a great engine but wasn't destined for a long life in production...

First you must understand that since 1949 Australia's automotive market was centred around relatively lightweight 6-cylinder cars built in Australia. Starting with the Holden, the market ramped up a bit when the first Falcons arrived. The S-series Valiant (powered by a relatively huge 225) arrived in 1962. By then Holden had a new 7-bearing engine in the works and were up to 179ci, Falcon had their 170 engine but both would go larger in time.

There were plenty of other cars on the market here, mostly 4-cylinder European and British cars, but BMC joined the 6-cylinder race by adding a couple of cylinders to their 1600cc B-series engine to create a 2.4-litre six for their new cars, the Austin Freeway and Wolseley 24/80. We now had four locally made 6-cylinder 4-door cars with station wagon variants. Holden and Ford also had utilities (pickups) while the Valiant line grew this addition in 1964 or so.

Your mention of local content is important. Our Sales Tax laws focussed on this closely and cars with 98% local content attracted this tax at the lowest rate. Fully imported cars paid the highest, around 50% and over when import duty was added.

The slant 6 was assembled here, but from components sourced from Canada. Other parts came from Canada, like like suspension components and transmission parts, Canada being a Commonwealth country and thus there was a lower level of import duty.

It became imperative to remain competitive to make the engines locally and as the sixties rolled towards and end this meant that the slant wasn't viable. It was heavily undersquare in a market where the savvy buyers knew that oversquare was more efficient. Chrysler Australia took over an experimental engine the Detroit people had been looking at as a possible truck engine, an engine they had been working on also as an experiment in building lightness into the engine.

As built in the US it had a taller block and was aimed at around 300ci, but the Australian engineers with the help of their American counterparts reduced the stroke, reduced the deck height and designed the 'hemi' head. It went into production in late 1969 and instantly provided more horsepower than any other six fitted to one of the popular cars. By 1971, and apparently against the advice of the American team, a 265 version was built.

While the 265 had about 220hp in 2bbl form, later renditions using triple dual-choke side draught Weber carburettors gave as much as 302hp. 

Along with the engine other locally made parts were added. In 1967 rear axles and transmissions made by Borg-Warner in Australia replaced the A903, A904 and 7.25 rear end, that there was no 4-speed initially has been mentioned. Unfortunately, Chrysler Australia didn't push for a 4-speed initially because their most colourful race driver (provided with under-the-lap assistance and cars) reckoned it wasn't necessary. "You only need a 4-speed off the start line," he insisted. They learned later, but lost a lot of opportunity in the period they awaited the 4-speeds.

Yes, the intake manifold is like the slant's, but there is even spacing between all the ports. The engine does suffer from some lack of final development problems, but it sits in the engine bay and is durable in normal use, usable in racing. It is not as tall sitting vertically as the slant is laid over at 30 degrees, just to rub it in to those who think the slant is lowered by its angling in the engine bay.

And it's a good hundred pounds lighter than the slant...


On Thursday, 25 December 2014 08:13:53 UTC-5, bobsbelvedere wrote:


Interestingly, Australia had a strict minimum domestic content requirement, which meant the cars were stuck with a 3-speed manual transmission, which hurt off-the-line acceleration.  Even so one magazine tested the car 0-60 mph at 8.1 seconds.  Maybe one of our Australian members can add some more to this discussion.  Bob from Maine

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