Pistons in a 77 440

[MagnumForce]

What are the differences between a late model 440's pistons and the pre 72 ones? I know the rods are shorter so i am buying a set of six pack rods to increase compression. Will i have to buy new pistons also or can i use the stock 77 ones?

[BSB67]

All the 440 rods are the same length.

The Six pack rods are heavy and would be my last choice.

The piston difference is the reason for the compression difference.  Specifically the compression height of the piston will determine a CR for a given head volume, i.e. the distance from the centerline of the pin to the top of the piston.

[Cooter]

As long as you ain't tryin to spin the damn thing to the moon and aren't looking for more than a hot street engine, cheapest route would be the Six Pack pistons and a rebalance. DO NOT RUN CLOSED CHAMBER IRON HEADS WITH THESE PISTONS.
Way too much compression.

[MagnumForce]

As long as you ain't tryin to spin the damn thing to the moon and aren't looking for more than a hot street engine, cheapest route would be the Six Pack pistons and a rebalance. DO NOT RUN CLOSED CHAMBER IRON HEADS WITH THESE PISTONS.
Way too much compression.

Ok so i can leave the stock rods in then? The heads i have are the stock heads from the 77 they aren't closed chamber right?

[ACUDANUT]

Ain't Six Pack pistons heavier, or was it the rods ?

[Cooter]

As long as you ain't tryin to spin the damn thing to the moon and aren't looking for more than a hot street engine, cheapest route would be the Six Pack pistons and a rebalance. DO NOT RUN CLOSED CHAMBER IRON HEADS WITH THESE PISTONS.
Way too much compression.

Ok so i can leave the stock rods in then? The heads i have are the stock heads from the 77 they aren't closed chamber right?

Your rods are fine, as are your heads. They are open chamber.

[Cooter]

Ain't Six Pack pistons heavier, or was it the rods ?

Both are heavier than 'LY' stuff.

[firefighter3931]

The speedpro 2355 6-pack replacement pistons are within a few grams of the factory high compression cast pistons so balancing is very easy. 

A 77 440 will have a cast crank which is an external balance engine so keep that in mind when purchasing pistons. 



Ron

[MagnumForce]

How does the cast crank affect the type of pistons i can buy? Or does it just affect the actual installation of the pistons?

[Nacho-RT74]

http://www.campbellenterprises.com/mopar_sealed_power_cast_pistons.htm

showing CH differences

[Cooter]

How does the cast crank affect the type of pistons i can buy? Or does it just affect the actual installation of the pistons?

The externally balanced cast crank engine will just need to be rebalance with a heavier than stock replacement piston.
if it were me, I'd find a forged unit and internally balance the engine. Plenty good cores today due to strikers...

[MagnumForce]

Ok is there any advantage to a internally balanced engine as opposed to an externally balanced one?

[Cooter]

Ok is there any advantage to a internally balanced engine as opposed to an externally balanced one?

Personally, I like not having to find a converter that's weighted, and I like the fact I can run a four speed without having to buy some high dollar flywheel and BS pilot bushing set up.

[MagnumForce]

sorry for bringing up an old thread but if i wanted to run stealth heads, which are closed chamber heads, what pistons would i need for that?

[Nacho-RT74]

you can use anyone... earlier ones the best for better compression. No one of the stock pistons will get the deck height anyway, both below the deck

Use earlier ones and a correct decking job on block could give you a nice quench using closed chambers and metallick headgasket.

However you can use nice KB Hyper pistons and will get you better numbers and less machine job on block.

All depending the investment you can afford and how much extra power want. Replacement stock pistons are cheaper, but then if you want quench, will spend on machine job. could affect engine geometry too, but relativelly "easy" to save.

KB Hyper pistons are priced a little bit more than stock replacements, and for quench will depend of block height. Maybe cut down a little bit less, but maybe still cut the deck. Will affect less the engine geometry.

Not a mech expert, but I have learnt a little bit

[Cooter]

Imo, make the parts fit the block, not the other way round.

[Nacho-RT74]

agreed