What alloy are my Arias pistons?

I bought a set of pistons second-hand but they came with no information sheet. I would like to know if they are 2618 or 4032 alloy so I can set the proper piston to wall clearance.

They are +.060" 426 Hemi pistons. Under the dome they are marked with the arias 'A' and the 'Speedmaster' logo. There are no other marks or coatings.

Skirts measured at 4.308"
Compression height measured about 1.765"
Dome Height is about .515"
Total Height from pin centerline to top is 2.28"
Dome volume is about 85cc
Pin diameter is 1.094" retained by spiral locks
Rings are 1/16, 1/16, 3/16

The skirts have a couple oil grooves going around them.
The wrist pin holes have 2 oiling holes per side. (4 per piston)

They may have been sold new to FHO in Canada in the early nineties. Know its a long shot, but any help would be much appreciated. I already E-mailed Arias so far, but haven't tried FHO yet.

If they are intended for racing they will NOT be the street alloy
If they have a job number or part number on them call Tim at FHO 905-797-2459 and ask him about them

Good luck with that. The very first stroker motor I ever did was done with some Ross pistons that Muscle Motors sold me. The pistons they sold me were blower pistons but they didn't tell me that. The shop set them up as if they were normal pistons and I scuffed one of them the first time the engine got warm. That Muscle Motors rotating assembly was only one step up from junk but I was too dumb to realize it at the time.

I’m gonna go with........ “aluminum alloy”

you be correct

Do you have anyone in your area that could do a metallurgical analysis for you? I see the aluminum percentage varies quite a bit between the two alloys (85% vs. 94%) with most of the difference being made up with silicon. This should be a cakewalk for a lab.

I reckon I'll just run them loose and let them slap, the block is junk so nothing to lose anyway. I'm thinking maybe like .006"-.008" piston to wall.



Why didn't I think of that? Lemme just pop on down to the corner metallurgical analysis lab. I hear they're running a 'buy one spectrum analysis, get one rockwell hardness test free' deal...

Unless they are something special your Arias pistons should be a 2618 alloy, which is what the vast majority of racing pistons use. One post mentioned scuffing with the 2618 alloy, and my experience is that since the 2618 alloy is also very hard, even with proper clearance, scuffing can be a problem, I know it has been on my engines over the years. Most of my engines go 4 years or so, and I like ross pistons, many times they will show scuffing on the cylinders. And it is the alloy, not the pistons.

The 4031 alloy forged pistons, with a 12% silicone content are getting popular, I would not hesitate to run them on say a bracket type engine, and also from my experience they do help a lot with cylinder wall scuffing. The expand about 15% less than the 2618 alloy, so you need less clearance, that helps keep the rings sealed up better as well.

The 4031 alloy is not the same as the Hypereutectic high silicone cast pistons which I think have around 20% silicone content. Several years ago they started using hypereutectic pistons in OEM engines, and I am seeing lots of stock replacement cast pistons for older engines coming as hypereutectic castings. I don't mind the change in material, except they have stopped putting in the warnings for clearance and ring end gap changes needed for hypereutectic VS regular cast pistons. So you got to be careful to figure out what you have.

Hmm.

SGS North America Inc.
Columbus, IN 47201

Element Materials Technology
Columbus, IN 47201
Daleville, IN 47334
Fort Wayne, IN 46803
South Bend, IN 46628
Warsaw, IN 46580

Team Industrial Services
Crown Point, IN 46307

Fort Wayne Metals
Fort Wayne, IN 46809


Hmm.

Got what I needed, .007"

Kinda on topic, how do you pronounce Arias? I've heard it pronounced uh-rye-us and air-ee-eez.

Kind of off topic but how do you pronounce Weiand? Why-and or Whee-and?

Julie Arias, former wife of Nick Arias Jr. pronounced it like Aireus, if I'm remembering correctly now
I haven't talk to her or seen her in a long while
She use to work for NHRA at a lot of the west coast national and division 7 races.

Y-and.

Almost cast in stone.....

I used to run three of them on a modified pull tractor, whenever calling for parts or even buying the complete motors which way back it was pronounced just as its reads, maybe the more "professional" drag people had to put a un needed spin on it.

How many guys pronounce Edelbrock as “eldebrock”?

Must be something with some guys tongues.

kind of like "al YOU min E yum"............