440 Six Pack/6BBL Myths and Lesser Known Facts
There are many myths and lesser known facts about the 440 Six Pack/6BBL engines produced by Chrysler.
These myths include:
- Six Pack Rods
- Camshaft and bolts.
- Compression ratio
- Pistons
- Cylinder heads
- Distributor
- Torque
- Production years
Let’s take a close look at these myths and expose the truth around these iconic Mopar engines. First, let’s dispel this myth.
Myth: The only difference between a 440 Six Pack/6BBL and a 440 High Performance is the intake and carbs.
False! The rest of this article explains why.
Six Pack Rods
Myth: The 440 Six Pack/6BBL had heavier connecting rods than the 440 High Performance engine.
Let’s start off in 1969, the first year of the engine. The 440 Six Pack/6BBL engines came with the same connecting rods as any other 440 produced that year. The length, width, weight and beams were the same. Except the rods were 100% Magnaglow inspected which may have made them more durable.
In 1970 the rods were beefed up across the beams resulting in a heavier, stronger connecting rod. These rods are what people call “Six Pack” rods but they were also installed in the 1970 and later 440 high performance engines. Therefore, they were not unique to the Six Pack engines.
Many people believe it was the Six Pack engine responsible for the stronger rod because racers were revving them higher than the regular 440. This resulted in many blown engines, but they are not unique to the Six Pack and Six Barrel engines.
Since the “Six Pack” rods came in many engines, it is one of the reasons why they are not difficult to find at the swap meets. I just picked one up for $10 at the latest Chrysler Nationals in Carlisle, Pa and hung it up on the wall in my man cave area.
Compression Ratios and Pistons
Myth: The 1969 440 Six Pack had a 10.5 compression ratio and pistons with valve reliefs.
While this was true in 1970, it wasn’t the case in 1969. The ’69 engines had the same compression, 10.1:1, and flat top pistons (with no notches) as the 440 High Performance. Although the top ring had a Molly filled face.
The Dodge and Plymouth Technical Service Bulletins released about the 440 3-2 bbl engines, listed 13 items about the engine different from the 440 High Performance. Not one of them mentioned different pistons or compression ratio, just the top ring.
The NHRA engine specifications for the 440 Six Pack/6bbl engines list the 1969 engine with 10.1:1 compression ratio, pistons without notches and the same deck clearance as the 440 engine. The NHRA was given these specs from the manufacturers.
In 1970, the engine was rated at 10.5:1 compression and did have the four valve reliefs in the top of the piston. At the same time, the 440 H.P. compression was decreased to 9.7:1.
In 1971, Chrysler claimed the compression was decreased to 10.3:1 but the notched pistons remained. Therefore, in reality, the 440 Six Pack/6BBL engines only had 10.5 compression for one out of the three years or four years, of production.
Four years? Yes, read down further about the production years of the engine.
Camshaft
The 440 Six Pack/6BBL came with a more aggressive camshaft.
For all the years of the Six Pack/6BBL engine, the camshaft had the same lift and duration as the 440 high performance engines.
Although the camshaft did have a different lobe design. The Six Pack/6BBL used Hemi valve springs and due to durability testing with the stiffer springs, it was necessary to use a low-taper design. This design allowed more rotation of the lifters in the bore to reduce excessive wear and tear.
For this reason, the lifters were also different. They were the same as the 440 H.P. except .0005 undersize and flat faced.
3 Bolt Cam
Myth: The 440 Six Pack/6BBL used a 3 bolt cam, same as the Hemi.
This is true for the 1970 and 1971 engines, but in 1969 the camshaft used the same sprocket, chain and number of bolts as the 440 High performance.
The technical service bulletins released by Dodge and Plymouth in 1969, about the 440 3-2 bbl. engine differences, does not state any difference with the cam sprocket, chain or number of bolts.
Different Cylinder Heads
Myth: The 440 Six Pack/6BBL engines were produced with better cylinder heads.
The casting numbers of the 440 Six Pack/6BBL cylinder heads were no different than any other 440 head. The ports and chambers were exactly the same and not modified.
Although there were some differences in the components installed on the heads.
- The valve springs installed were the same as the Hemi engine’s springs.
- The rocker arms were stronger than the 440, although the same design and appearance.
- The valves used a chrome flash valve stem.
Distributor
Myth: The 440 Six Pack/6BBL engine had the same distributor as the 440 High Performance.
The 440 Six Pack/6BBL engines were produced with a dual breaker distributor.
Production Ended in 1971
Myth: Chrysler ended the production of 440 Six Pack/6BBL engines in 1971.
1971 was the last year of the high horsepower and compression muscle car engines or was it? In 1972 the street Hemi was gone but Chrysler planned on continuing the 440 Six Pack and Six Barrel, as shown in these 1972 brochures. Let’s take a closer look.
Dodge planned on having the big block Six Pack in the Charger Rallye model. In this 1972 Charger brochure, you’ll see the 440 V8 Six Pack under the optional engine list.
This is a 1972 Dodge Brochure indicating the 440 Six Pack as an option on the Charger Rallye.
Plymouth was planning the same in the GTX. In this 1972 Plymouth Satellite brochure , in the Road Runner description, it states the GTX engines include a 440 4 barrel or 6 barrel V8.
In addition, the 1972 service manuals also included the Six Barrel engine in their fuel, engine and engine specifications. The 1972 dealer salesman data books also included the engine.
Planning is one thing but were these cars actually built?
Yes, today there is one known ’72 GTX and 2 Charger Rallye cars produced with the mighty 440 from the factory. Rumor is 6 or 7 of them were produced before Chrysler shut the door on the iconic 440 engine.
This video below tells a story about the 1972 Plymouth GTX which came from the factory with a 440 Six Barrel.
So the next time you come across a 1972 Charger or GTX somewhere in a barn or the weeds, you may want to take a closer look at it. I could only imagine a few of these cars were overlooked and eventually destroyed because no-one bothered to check the vin.
Torque
Lesser Known Fact: The 440 Six Pack was rated with the same torque as the 426 Hemi.
Many people are aware the 426 Hemi was Chrysler’s most powerful engine during the muscle car era. The 426 Hemi was built for higher RPMS on the ovals which made it less of a torque monster on the street.
It was a different story for the 440 Six Pack rated at 490 foot pounds of torque at 3,200 rpm. This equaled the Hemi’s torque which was also rated at 490 ft. lbs. but at 4,000 rpm.
This lower rpm torque would give the 440 Six Pack the advantage off the line many times during a stoplight to stoplight race. Of course, in the long run, the Hemi would outrace the Six Pack once the race over.
More 440 Six Pack Articles
440 Six Pack/6BBL Horsepower and Torque
