difference between a 440 HP and 440 six pack motor

[CRAIGXLH1]

what the difference between a 440 HP and 440 six pack motor beside the intake and carbs. do they have a difference block or heads, can you tell the
difference by looking at them
thanks
craig

 

[AR67GTX]

I remember the 6-pack has heavier duty (and heavier) rods. Seems like the camshaft had a little more duration on maybe the exhaust side.

 

[RustyRatRod]

The six pack pistons also have a greater compression height. Also, if I remember correctly, because of all the internal mass (huge mafungo rods) the six pack is also externally balanced.

 

[Supershafts]

what the difference between a 440 HP and 440 six pack motor beside the intake and carbs. do they have a difference block or heads, can you tell the
difference by looking at them
thanks
craig

By looking at them without intakes, no you wouldn't see a difference you would need to remove the heads to see which was which or remove the pans or put them both on scales. The 6pk will be heavier, but if the 440hp was a late edition it may have gotten 6pk rods thrown in it also just because as many 440s did especially pd vehicles got them thrown in.
Besides you wouldn't want 6pk rods anyway other than a coffee table item

 

[69Coronetrt]

First, what year are we talking about? The 69 internals were different than the 70-72s.

 

[Garys1969RR]

What is the actual factory spec for the 440 6-pak piston compression height? I heard some had a positive deck clearance. ( Above the deck). While most 440s have a below the deck clearance. .015" to .020" on 60s models. Late 440s (77-78) have .100" or more below deck.

 

[Meep-Meep]

Six pack pistons are flat tops with have 4 valve reliefs and have a compression height of 2.065". They are just about zero deck but not positive. The only positive deck wedge motor that I'm aware of is the 383 HP, but even so I have yet to see one. My numbers matching 68 RR was completely original in 1982 and the pistons were not positive deck. That may be the blueprint spec but reality often doesn't follow the print.

Other differences are: The cam is a low taper lobe design but has the exact same specs as the Magnum cam. Valve springs may be stiffer. Distributor advance curve should be different. Rods have wider beams. Externally balanced because of the heavier rods. 6 QT oil pan perhaps in 70-71 only.

 

[65 Plymouth Satellite 426]

Aren't The Six-Pack Rods Marked With An LY on Them?

 

[Garys1969RR]

I believe all 440 rods are marked "LY". At least the ones I've seen were. Even from a cast crank motor. Not sure what the 6-pak rods were marked with. But I do know they were heavier duty. Thats one reason the cranks are externally balanced.

 

[Garys1969RR]

Thanks, Meep Meep. So a 0 deck 440 piston would have a C/H of 2.067 I believe. Which makes the 440 6-pak with a C/H of 2.065 have a .002" below deck clearance, right? So by ordering 6-pak pistons I could gain some compression I think.

 

[Cranky]

In 1970, all HP engines got the 'big' rod because they were having warranty issues with rod failure but all Mom did was make the problem worse by using a heavier rod with the same size rod bolt. The 6 pack rod works well when prepped. I used to grind them heavily and install SPS bolts and go racing. This was back in the early 80's before good aftermarket rods were readily available....never had a failure with the old no good big rods And the 6 pack pistons are blueprinted to be .020 below deck if the deck is on the money from the factory.

 

[Cranky]

Aren't The Six-Pack Rods Marked With An LY on Them?

No LY markings on a 6 P rod...

 

[Sweet5ltr]

Also, six pack camshaft was a 3-bolt design and was split pattern. .464 int./.464 exh. 268*/284* duration (or so I've read, do not have my engine manual with me). Not sure of LSA, probably 114-115. I have a 73' HD highway patrol 440 in my car that was internally balanced, with forged cranks and six pack rods from the factory. Just had standard flat-top pistons (8.5:1CR), HP camshaft from 73', and a four barrel.

 

[Cranky]

I've always heard that cop car 440's were supposed to have 6 pack rods but the few I've torn down just had LY's in them. Same goes for motor home 440's....never found any big rods in them either but they were all later models too. Mom may have used the big rods until they ran out.

 

[benno440]

if the 6 pack is externally balanced then you should be able to see the externally balanced harmonic balancer right?

 

[Sweet5ltr]

I've always heard that cop car 440's were supposed to have 6 pack rods but the few I've torn down just had LY's in them. Same goes for motor home 440's....never found any big rods in them either but they were all later models too. Mom may have used the big rods until they ran out.

Read some Chrysler info that lead me to believe that 1974 onward, most were built with cast cranks and standard rods. 1973 was the last year of the forged steel crank/heavy rod combo due to availability. Engine is INTERNALLY balanced, other than externally like the original 1969 1/2-1971 six pack engines. Piston weight is the dividing factor with the earlier 440 "six pack rod" combo and the move to external balancing. Later years, with forged cranks, the engines were internally balanced with the 'six pack' rods. Piston weight was reduced for this move.

 

[Cranky]

I've had a few tell me that they pulled late model engines out of motor homes that had the big rod but since I didn't see it....oh well lol. Yeah, all the later model cast crank engines were external balance but I've seen a factory internal balance 6 pack engine....all the ones I've seen were all external including the 70 and up 440HP 4 barrel.

 

[Sweet5ltr]

I've had a few tell me that they pulled late model engines out of motor homes that had the big rod but since I didn't see it....oh well lol. Yeah, all the later model cast crank engines were external balance but I've seen a factory internal balance 6 pack engine....all the ones I've seen were all external including the 70 and up 440HP 4 barrel.

It surprised me as well. If the engine would have came with a cast crank it would have been externally balanced. Engines with forged cranks and six pack rods were internally balanced after 1971 when the piston weight was lightened or so far that is my 'best' explanation. I also believed that all engines with the six pack rods were externally balanced prior to my rebuild, when I researched the topic in detail. It was luck to find this configuration. Car also had 213 HD cylinder heads on it, with additional cooling passages. It looks like MoPar was looking out for the Florida Highway Patrol and wanted them to have the last of the 'good stuff'. We didn't even realize until recently, that their was no "440" Road Runner in 1968-1970.. Only the six pack was offered in late 1969, and not the standard 440/four barrel configuration. I guess the thing to do was to pick up a 383 car and toss some 440 badges on it in the late 60's and early 70's.

Good write-up on Internal and External balanced applications:
http://www.dodgecharger.com/forum/index.php?topic=63186.0

 

[Cranky]

I knew about the 68-70 road runners not coming with the 4 barrel 440 but didn't know about the post 71 balance deal. Uncle Sam drafted my butt in early 71 and since mom did some radical body changes that I didn't much care for (not to mention lowering compression for 71 a ton), I kinda didn't pay much attention to her cars after that except for the 71 Cuda and even that didn't much catch my eye until 86 when I bought one lol

 

[RustyRatRod]

The six pack has three carburetors and the 440 HP has one. heh.