Bad Forged Pistons?

[1NASTYGN]

I have less than 200 miles with these pistons. I purchased from a reputable forum vendor and I want to see if this would be considered " normal" wear before I sell to another member. Seems like coating is falling off, pistons were not hitting cylinder walls

 

[Chuck Leeper]

Where did that stuff end up, in the oil pump screen?
Looks to me that the coating was put on but not cured.

 

[1NASTYGN]

On screen, we thought it was silicon.

 

[haywire4130]

Egads! Are they std bore? What was the piston to cyl clearance? Definately looks like a defective coating

 

[1NASTYGN]

.40 Block was over bored and I was not comfortable with the build to begin with. My new builder feels it is defective coating. I spoke to the vendor I purchased from and I was told they are Wiseco custom pistons he sells with his stoker kits.

 

[David Husek]

The pistons were purchased from me. The problem here is the pistons are 3.840" and the block was bored to have .008" - .009" clearance. This info is from speaking with his new engine builder on 3 way calling. From the pictures I would say the pistons are no good. Excessive clearance will rock the piston in the bore and will have excessive wear on the skirt as you are seeing. The way you described the noise the motor made is explained by the excessive clearance. The spec is .0045" clearance. You are just about double what is recommended. The statement that the piston does not touch the cylinder wall is totally false and your pictures show this clearly as the coating has been removed from rocking. I would definitely find a good builder and I recommended two east and west of you that can get the job done for you.

 

[bison]

What was the bore diameter?


Sent from my iPhone using Tapatalk

 

[1NASTYGN]

David I will send you pics of the cylinder walls and I'm not going to go back and forth with you over this. I understand the coating would wear off where the piston would slap on the cylinder. What we are seeing is coating falling off. As you stated on our phone conversation. You know of no one who has had to rebuild a motor using one of your stroker kits and can't defend that this could be a defective piston. You have always done me right with parts and pricing and in no way am I saying your parts are not up to par. I had a bad machine shop build my motor and I have learned my lesson. I wanted to make sure I didn't resell junk to another board member is all. I will rebuild using a reputable builder.

 

[turbo89]

David I will send you pics of the cylinder walls and I'm not going to go back and forth with you over this. I understand the coating would wear off where the piston would slap on the cylinder. What we are seeing is coating falling off. As you stated on our phone conversation. You know of no one who has had to rebuild a motor using one of your stroker kits and can't defend that this could be a defective piston. You have always done me right with parts and pricing and in no way am I saying your parts are not up to par. I had a bad machine shop build my motor and I have learned my lesson. I wanted to make sure I didn't resell junk to another board member is all. I will rebuild using a reputable builder.

how much do you want for the pistons .. if your only concern is the coating .. who cares.. that's easily remedied .

 

[1NASTYGN]

I have everything listed on parts for sale. LOL

 

[1NASTYGN]

More pics.

 

[turbofabricator]

Looks to me like the bottom of the bore was not deburred and it scraped the coating off of the piston. Common mistake for many builders.

 

[1NASTYGN]

Bore size is 3843 all cylinders

 

[earlbrown]

Good god. If that number is accurate, You might have around .009"+ cylinder to wall clearance.


Depending on the architecture, the slug might be flopping over at the bottom of the bore and squeegeeing the OD right off everytime it goes past BDC

 

[1NASTYGN]

It is bud. I have everything for sale on another post.

 

[earlbrown]

Since it's 4.3 thou oversized, I'm guessing someone just honed the crap out of it until it was clean then let it fly with some STD pistons?

If the rest of the block is in good shape I can make you some new +.005" pistons to match your messed up bores if you want to save it.

 

[1NASTYGN]

I already purchased another block and David Husek made me a new set of pistons to match the rods and crank I purchased originally. Stand up guy.
I have the block with billet caps, 215/220 cam, double roller chain, and front cover for sale. less than 200 miles. no track or dyno time. I'm not sure if anyone would be interested in the 3840 long arm stroker pistons.

 

[1NASTYGN]

I do have the bock for sale and just had Wiseco re coat the pistons. The pistons are for sale also