Re: Cast pistons VS. Cast Pistons LOL!!

[biljoh@xxxxxxxxxxxx]

On September 22, 2004 Tom Jennings wrote:

> > It might be that back-in-the-day that the quality of the casting was
> more consistent -- mix, thickness, porosity, cooling rate, cooling
> evenness, alloy used, etc. Manufacturing is a tricky process, there's
> lots of room for variation; really high quality manu's more readily
> throw parts back into the scrap bin if something is out of spec; lower
> cost manu's like Badger might accept them.

  -That certainly makes sense and could explain why some of my OE pistons had different markings than the others 3 or 4 of them actually. They must have thrown out the questionable castings.-
> 
> There's a calculus for this, but we don't have access to it. When
> there's just one of you, and you're making one motor, paying out of
> pocket, saving $500 cast vs. forged pistons probably isn't worth it.
> YMMV.
> 
     -I agree only if the forged are needed for the application- and they can have problems too-

>  
> Pinholes in castings are caused by bubbles and pockets of gas, implying
> poor quality control, when the part is machined the top half of the
> bubble is removed leaving a pit. You have to wonder if there aren't
> other bubbles in the metal, say in the skirts, or near the top ring
> groove...
> 
  -I'll be sending back the piston that has the small pinhole in the top even though my builder said he has seen it before and that these flaws are common to cast pistons, I don't like the fact that the other 7 are perfect and that one has that extremely small pinhole, and you are right I have no idea if there isnt a big bubble under that pit, luckily my machine shop has a brand new catalog and can get the same pistons brand new, badger has started making them again, hopefully the vendor will swap it for me though and save me 40.some dollars for a single if I have to buy one, and hopefully they won't want the whole set back to exchange for another set that could have the same deal 7 perfect pistons and one with a minor flaw(roll eyes).

> They're "good enough" parts for "good enough" rebuilds, eg. a repair
> shop does a rebuild on an older car, it lasts long enough to be way out
> of the warranty of the repair shop. It can even be the most honest shop
> in the world; if an engine fails years later, how would the shop know?

  Unfortunatley you are right about some shops that would let an engine go out the door that could have a problem, but I am going to take the "When in doubt, toss it out!" approach, that pinhole piston is going back. 


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