Which pistons to get?

[BLK 68 R/T]

Long story short - my brother has a 68 Coronet 500, original 318 auto, now 440 4 speed. He had the 440 rebuilt several years ago and it ended up falling victim to the install of the dreaded low comp stock replacement pistons. Currently the motor runs pretty good on the highway but lacks the power it should have and it also has just never ran good at slower speeds, maybe due to the 509 cam + iron intake and small carb?? I don't know for sure? but he is tired of his engine "sucking" and is open to replacing the pistons and whatever else is needed.

Car is used for cruising around town and trips on the highway that total about 150 miles round trip when he comes to town to visit.

His current setup is:
440 bored .030 over, 3.75 stroke crank.
3.55 rear gear
275/60/15 rear tire
906 heads, freshened up with new stock size valves and new valve stem seals, stock rockers
Original iron intake with 625 carter carb
Cheap painted hooker headers that hit everything
Mopar "509" hyd flat tappet cam


Plan for upgrade is:

Sidewinder heads, 84cc - set up for the below cam + keep the stock rockers
I have a brand new Cam Motion hyd. flat tappet cam I gave him, .496/.496 lift @ 112 LSA + new USA made Johnson lifters
TTI 1 7/8 headers
Edelbrock RPM intake
Quickfuel 850 CFM carb

But on the pistons - There are quite a few choices, KB237, Icon, 440 source, Speed-pro 6 pack replacement ones, etc.
What would be a good piston choice for this combination?

I know (from this site, thank you!) that we need to make sure the machine shop he chooses has a torque plate for boring and honing as well as setting the pistons up at 0 deck with a .039 head gasket for good quench.

Also open to feedback/critique on this proposed combination of parts as well.

[c00nhunterjoe]

http://www.dodgecharger.com/forum/index.php/topic,118292.0.html

[BLK 68 R/T]

http://www.dodgecharger.com/forum/index.php/topic,118292.0.html

Thanks, I have read through that before as well as a whole bunch of the proven combos. None of which really answers my question as to which piston would be best suited for the engine. Unless you are referring to the talk of the 2355s being a good piston to choose since they are mentioned quite a bit in the link you sent?

[BSB67]

Long story short - my brother has a 68 Coronet 500, original 318 auto, now 440 4 speed. He had the 440 rebuilt several years ago and it ended up falling victim to the install of the dreaded low comp stock replacement pistons. Currently the motor runs pretty good on the highway but lacks the power it should have and it also has just never ran good at slower speeds, maybe due to the 509 cam + iron intake and small carb?? I don't know for sure? but he is tired of his engine "sucking" and is open to replacing the pistons and whatever else is needed.

Car is used for cruising around town and trips on the highway that total about 150 miles round trip when he comes to town to visit.

His current setup is:
440 bored .030 over, 3.75 stroke crank.
3.55 rear gear
275/60/15 rear tire
906 heads, freshened up with new stock size valves and new valve stem seals, stock rockers
Original iron intake with 625 carter carb
Cheap painted hooker headers that hit everything
Mopar "509" hyd flat tappet cam


Plan for upgrade is:

Sidewinder heads, 84cc - set up for the below cam + keep the stock rockers
I have a brand new Cam Motion hyd. flat tappet cam I gave him, .496/.496 lift @ 112 LSA + new USA made Johnson lifters
TTI 1 7/8 headers
Edelbrock RPM intake
Quickfuel 850 CFM carb

But on the pistons - There are quite a few choices, KB237, Icon, 440 source, Speed-pro 6 pack replacement ones, etc.
What would be a good piston choice for this combination?

I know (from this site, thank you!) that we need to make sure the machine shop he chooses has a torque plate for boring and honing as well as setting the pistons up at 0 deck with a .039 head gasket for good quench.

Also open to feedback/critique on this proposed combination of parts as well.

What is your plan for rods?  I would suggest aftermarket rods.

If it is in the budget, a light weight piston is always good

[BLK 68 R/T]

What is your plan for rods?  I would suggest aftermarket rods.

If it is in the budget, a light weight piston is always good
[/quote]

Had not really thought about rods. Just assumed that the factory ones were fine for what he is doing. I will definitely suggest changing them though and see what he says. Thanks for the suggestion.

[c00nhunterjoe]

Imo, the 2355s are too heavy given options today. Over 1100 grams if memory serves. Icon and probe make nice affordable pistons, or for a mild build a kb 237 would be a very similar piston as far as compression height goes, to the 2355. Depending on the machining, they will sit .010 to .015 in the hole and be a respectable, inexpensive choice. I have run the 236s which have the step dome on pump gas with no problems. There is no perfect part number for you at this point. There are alot of other variables stilk.

[firefighter3931]

My old 446 had Factory LY rods with Speedpro 2355 pistons and made 535hp/540tq on pump gas with a big solid cam and mildly ported Edelbrock RPM heads. Spun that motor to 6200 many times. Of course the rotating assembly was balanced and new ARP rod bolts were installed. The nice thing about the 6-pack replacement pistons is that they weigh close to the stockers so balancing is easy for the machine shop. 

For a cruiser you don't really need an aftermarket connecting rod or lightweight piston....especially with a hydraulic cam that won't ever see the high side of 6000 rpm. 


Ron

[69wannabe]

My old 446 had Factory LY rods with Speedpro 2355 pistons and made 535hp/540tq on pump gas with a big solid cam and mildly ported Edelbrock RPM heads. Spun that motor to 6200 many times. Of course the rotating assembly was balanced and new ARP rod bolts were installed. The nice thing about the 6-pack replacement pistons is that they weigh close to the stockers so balancing is easy for the machine shop. 

For a cruiser you don't really need an aftermarket connecting rod or lightweight piston....especially with a hydraulic cam that won't ever see the high side of 6000 rpm. 


Ron

X2!!! for a driving around town engine the 2355's work great and are not going to hold you back. I built a 440 years back with these pistons and a mild cam with cast iron heads and it was plenty peppy for street driving. 

[BLK 68 R/T]

Thanks everyone for the replies. I will talk with my brother and see what his budget will allow.

[c00nhunterjoe]

see what his budget will allow.

This is the 1st step before any decisions or questions should start.

[BSB67]

My old 446 had Factory LY rods with Speedpro 2355 pistons and made 535hp/540tq on pump gas with a big solid cam and mildly ported Edelbrock RPM heads. Spun that motor to 6200 many times. Of course the rotating assembly was balanced and new ARP rod bolts were installed. The nice thing about the 6-pack replacement pistons is that they weigh close to the stockers so balancing is easy for the machine shop. 

For a cruiser you don't really need an aftermarket connecting rod or lightweight piston....especially with a hydraulic cam that won't ever see the high side of 6000 rpm. 


Ron

Right, but if you rebuild a LY rod with good bolts, you'll be within $150 of stronger, lighter and better aftermarket rods.  Price difference for a light weight piston verses a 2355 is $200.  So back to my original statement, what will your budget allow.  This is $300 to $350 very well spent in my opinion.