Hello,
A couple of you have shown some interest in Chrysler 6’s built in Australia otherwise known as the Hemi 6.
Before you get excited about spark plugs in the rocker cover type Hemi it’s nothing like that style.
The head chamber is similar in shape to a true hemi head but that’s about. The word hemispherical was used during the design process and an eager marketeer grabbed the phrase and ran with it.
The engine was originally designed at Highland Park in the US as a light truck engine. Ultimately it never went any further until the ever resourceful aussies snapped it up, tweaked it and went on to produce it here in Aus.
Around this time GM and Ford Australia had US derived engines in performance cars, 350,327and 307 chevy’s in the Holden’s and Ford had the Windsor and Cleveland V8’s.
Chrysler had the 273, 318 and 340.
The early 70’s also began the change into smaller more efficient smog junk engines. GM and Ford went on and designed their own six’s here in Aus.
Chrysler had the slant six but needed a change so along came the Hemi 6.
They were built in three sizes, 215, 245 and 265 cubic inches.
There was a 245 Heavy Duty produced for the smaller range of Dodge trucks. The oil pan is unique on the engine. That is fact. There are rumours that the truck version is a forged crank with heavier rods. I do not know this to be factual but I do have one and will do an autopsy on it shortly and find out for sure.
Touring car racing in Aus was a big marketing tool back then. Ford had the Falcon GTHO with a 351 Cleveland and Holden were pushing there 350 Chevy powered Monaro.
Chrysler did some serious testing and tuning and decided to campaign the six instead of going with the 340 small block. It is rumoured that the Chrysler bodies at that stage handled like an egg on a glass table with the weight of the V8 up front but with the six it was almost civil that’s how it went.
As you would imagine when Chrysler announced they were going to campaign an inline six a hundred cubic inches smaller in full size body there were a lot of expletives and gasps.
The early Valiant pacers did okay but it wasn’t until the E49 triple Weber carb 300hp version in the Charger turned up people started to sit back and take a look. A publicity stunt was conducted, which I might add may have gone very wrong for Chrysler which involved a drag race between the Falcon GTHO 351 against the Valiant E49 six pack….lucky for Chrysler the Hemi 6 won.
Whilst they were quick Chrysler never really set the world on fire though.
These engines are long stroke engine with a wide bore spacing which resulted in a long crank and cam.
It’s a 7 bearing crank. The block is very light for what they are.
Now throw 6500-7000 rpm into the mix they had some issues. One of the more notable is flywheel bolts continually loose or broken and the autos, broken flex plates.
It was common to machine six holes in the end of the crank and press fit dowels then press fit the flywheel to the dowels plus loctite and wire the bolts.
It’s a harmonic problem and it played havoc with the racers running at high rpm for extended periods.
Australian cars with the Hemi 6 had either 3 or 4 speed manual or Borg Warner 35 auto. There was a run done with the 727 Torqueflite. This block is physically different. The 904 Torqueflite was was never installed at the factory. They did however use the 904 torque converter with the BW35 auto the the taxis.
The Hemi 6’s use a small cross shaped steel plate as a flex plate to the converter. The starter ring gear is mounted on the converter.
For performance your choices in auto are BW35 for very mild and that’s it. The 727 block is very rare and hard to find so adapting is what you do. You can adapt a small block Torqueflite with an adapter setup…more often than not this isn’t successful.
GM trans work okay but a lot of work. New 4340 billet flywheel drilled to suit a TH400 small converter, adapter plate, powerglide with TH400 input shaft plus a handful of other bits n pieces.
If anyone wants one of these six’s try and find a later 1980-1981 S block. It has a big S cast in the side of it. These blocks can be bored .120” which is 4”. Now a big caution ! Any block you want to bore past .060” you need to sonic test. They suffered badly from core shift during casting. It is not uncommon to run out of metal going this big and it’s also not uncommon to go through a truckload of blocks to find a good one.
You can get a 320ci 4340 stroker crank for the 265 block along with forged rods and pistons.
There is a Hemi 6 here in Aus that runs low 7 sec quarters with factory crank, block and head. Everything is full of grout, girdled and braced.
For people like us 300hp is easy power with this engine and with some assistance, blow or squirt or both 400hp is easy.
A couple of you have shown some interest in Chrysler 6’s built in Australia otherwise known as the Hemi 6.
Before you get excited about spark plugs in the rocker cover type Hemi it’s nothing like that style.
The head chamber is similar in shape to a true hemi head but that’s about. The word hemispherical was used during the design process and an eager marketeer grabbed the phrase and ran with it.
The engine was originally designed at Highland Park in the US as a light truck engine. Ultimately it never went any further until the ever resourceful aussies snapped it up, tweaked it and went on to produce it here in Aus.
Around this time GM and Ford Australia had US derived engines in performance cars, 350,327and 307 chevy’s in the Holden’s and Ford had the Windsor and Cleveland V8’s.
Chrysler had the 273, 318 and 340.
The early 70’s also began the change into smaller more efficient smog junk engines. GM and Ford went on and designed their own six’s here in Aus.
Chrysler had the slant six but needed a change so along came the Hemi 6.
They were built in three sizes, 215, 245 and 265 cubic inches.
There was a 245 Heavy Duty produced for the smaller range of Dodge trucks. The oil pan is unique on the engine. That is fact. There are rumours that the truck version is a forged crank with heavier rods. I do not know this to be factual but I do have one and will do an autopsy on it shortly and find out for sure.
Touring car racing in Aus was a big marketing tool back then. Ford had the Falcon GTHO with a 351 Cleveland and Holden were pushing there 350 Chevy powered Monaro.
Chrysler did some serious testing and tuning and decided to campaign the six instead of going with the 340 small block. It is rumoured that the Chrysler bodies at that stage handled like an egg on a glass table with the weight of the V8 up front but with the six it was almost civil that’s how it went.
As you would imagine when Chrysler announced they were going to campaign an inline six a hundred cubic inches smaller in full size body there were a lot of expletives and gasps.
The early Valiant pacers did okay but it wasn’t until the E49 triple Weber carb 300hp version in the Charger turned up people started to sit back and take a look. A publicity stunt was conducted, which I might add may have gone very wrong for Chrysler which involved a drag race between the Falcon GTHO 351 against the Valiant E49 six pack….lucky for Chrysler the Hemi 6 won.
Whilst they were quick Chrysler never really set the world on fire though.
These engines are long stroke engine with a wide bore spacing which resulted in a long crank and cam.
It’s a 7 bearing crank. The block is very light for what they are.
Now throw 6500-7000 rpm into the mix they had some issues. One of the more notable is flywheel bolts continually loose or broken and the autos, broken flex plates.
It was common to machine six holes in the end of the crank and press fit dowels then press fit the flywheel to the dowels plus loctite and wire the bolts.
It’s a harmonic problem and it played havoc with the racers running at high rpm for extended periods.
Australian cars with the Hemi 6 had either 3 or 4 speed manual or Borg Warner 35 auto. There was a run done with the 727 Torqueflite. This block is physically different. The 904 Torqueflite was was never installed at the factory. They did however use the 904 torque converter with the BW35 auto the the taxis.
The Hemi 6’s use a small cross shaped steel plate as a flex plate to the converter. The starter ring gear is mounted on the converter.
For performance your choices in auto are BW35 for very mild and that’s it. The 727 block is very rare and hard to find so adapting is what you do. You can adapt a small block Torqueflite with an adapter setup…more often than not this isn’t successful.
GM trans work okay but a lot of work. New 4340 billet flywheel drilled to suit a TH400 small converter, adapter plate, powerglide with TH400 input shaft plus a handful of other bits n pieces.
If anyone wants one of these six’s try and find a later 1980-1981 S block. It has a big S cast in the side of it. These blocks can be bored .120” which is 4”. Now a big caution ! Any block you want to bore past .060” you need to sonic test. They suffered badly from core shift during casting. It is not uncommon to run out of metal going this big and it’s also not uncommon to go through a truckload of blocks to find a good one.
You can get a 320ci 4340 stroker crank for the 265 block along with forged rods and pistons.
There is a Hemi 6 here in Aus that runs low 7 sec quarters with factory crank, block and head. Everything is full of grout, girdled and braced.
For people like us 300hp is easy power with this engine and with some assistance, blow or squirt or both 400hp is easy.
