Would you use this piston? (Pics)

[jenkins71]

Hi, just bought a mildly used set of pistons for my 440 build. Most of them look good, like this one:


But this one has some detonation damage around the edges.


Would you re-use it? I single I can buy a single piston for about $50 on summit. Wouldn't be a big deal to replace it. Is that a viable option?

Also, how important is it for a street/occasional strip motor to have the piston and rods all balanced?

I know I will have to balance my crank, correct?

 

[69Bee]

It actually looks like water damage to me. Even if you were able to get a close replacement, TRW has been out of business for quite some time, I would expect to see a weight difference between new and old. I would run all of these, or buy a new set. Because of the difference between these and stock, I would definitely balance the engine.

 

[lewtot184]

old heavy trw 11.5 rod breaker. i'd find something else.

 

[dvw]

If it is detonation (can't tell from the pic) the ring grooves should show damage as well. Look at the top of the ring groove. If the upper land looks good they should be fine. Many people ran this piston for years. It's an old design that requires a fair amount of clearance and are heavy. For a budget street occasional strip they work. In my experience they tend to use oil.
Doug

 

[Cranky]

A buddy and I ran a 69 road runner in Super Street using those pistons swinging on prepped 6 pack rods turning 7k with it! I would smooth the sharp edges to guard against hot spots. You don't have to go crazy with it. Use a very small rotary file and just dress the edges of the pits. And in the past, I've taken as much as 200 grams out of those pigs by ball end milling the bottom side.

 

[Seax440Dodge]

It actually looks like water damage to me. Even if you were able to get a close replacement, TRW has been out of business for quite some time, I would expect to see a weight difference between new and old. I would run all of these, or buy a new set. Because of the difference between these and stock, I would definitely balance the engine.

TRW isn't out of business per se, they just stopped making pistons... they have their hands in a lot of stuff...

as far as the piston, that looks like a L2295

 

[Meep-Meep]

You should bead blast the tops and get a really good look before making any decisions. However, I do see some pits on the edge that might cause a hot spot if left alone. What you might do is carefully blend those pits smooth and hopefully you don't remove a ton of material doing it. Another observation is in a 440 that is an 11:1 CR piston with an open chamber head and you don't want that on the street. I have the exact same set of pistons that I got really cheap and my plan was to cut the domes off and make them into zero deck flat tops, so if you have nothing in those and have access to a mill start fly cutting. Balancing in my opinion is a must no matter what, but then again balancing machinery that spins 60 KRPM is what I do for a living so I'm a bit **** regarding that.

 

[super-bee_ski]

"..............but then again balancing machinery that spins 60 KRPM is what I do for a living so I'm a bit **** regarding that." End quote"

I'm dizzy alreaedy!

 

[jenkins71]

Thanks for the input guys. Just dropped em off at my machine shop. The machinist reassured me, saying "eh, that's nothin" in regards to the pitting. He is going to check em out in terms of wear, and bead blast them if need be.
Yeah, I guess I should get everything totally balanced, not just the crank. Mo money! It's all good though.
How come this piston uses thin rings?

- - - Updated - - -

Also, I believe my CR will be okay, as my heads are actually 96cc and I am using a thick head gasket.

 

[bigmanjbmopar]

Just get new and get rid of any questions, I love me some Diamond pistons

http://www.diamondracing.net/pdf/MoPar-Section.pdf

 

[69Bee]

TRW isn't out of business per se, they just stopped making pistons... they have their hands in a lot of stuff...

as far as the piston, that looks like a L2295

That is basically what I meant; they are out of the piston business.

 

[jenkins71]

Dudes, I can't afford new pistons, so i got a lightly used set.

I'm scrounging over here!

 

[super-bee_ski]

COOL!

"Just do it"

They will be OKAY...

 

[jenkins71]

COOL!

"Just do it"

They will be OKAY...

this guy rules!

 

[jenkins71]

Hey so the crank HAD 2266 pistons in it. Any idea if these 2295's are heavier or lighter than the 2266's?

Just wondering, because i heard Mallory metal gets pricey...

 

[Cranky]

I'm pretty sure the pop ups are heavier since they have a higher compression height. That's the way they did their pistons. I know for a fact that flat top 6 pack pistons are heavier than the 66's....

 

[jenkins71]

Can a machine shop remove weight from all the pistons rather than adding Mallory metal to the crank?

Seems like that would kills 2 birds with one stone.... Lighten the heavy pistons and prevent the use of expensive heavy metal...


Man, my mind is constantly consumed with this engine build! I can't concentrate on anything else...

 

[Cranky]

Can a machine shop remove weight from all the pistons rather than adding Mallory metal to the crank?

Seems like that would kills 2 birds with one stone.... Lighten the heavy pistons and prevent the use of expensive heavy metal...


Man, my mind is constantly consumed with this engine build! I can't concentrate on anything else...

Read post #5. If I can remove weight, so can any machine shop with a milling machine and a piston vise. Thing is, it's time consuming but how long does it take to rebalance the rotating assembly?

 

[jenkins71]

Are there any benefits to having a heavier set of pistons? I want this thing to be a low-to-mid torque monster rather than a horsepower screamer.

 

[lewtot184]

they should balance ok with a stock ly rod and steel crank, or at least the last one i played with did. the piston is about 825grms but if i remember correctly they have a heavier than stock pin.

doing a zero deck would require .050+ cut off the block. pretty sure those have a 2.03 compression height.

- - - Updated - - -

Are there any benefits to having a heavier set of pistons? I want this thing to be a low-to-mid torque monster rather than a horsepower screamer.

no. the piston has to stop and change direction every crankshaft revolution. as revolutions increase the stress of starting, stopping, changing direction of the heavy reciprocating parts causes parts failures. those pistons have been obsolete for decades. they were used because they were easy to get and we didn't have options, didn't know better, or didn't know how to find options. they're throwback to mid '60's technology. those pistons with an open chamber head and pump gas are problematic. the dome configuration doesn't work well with plug location.