96 5.7 carbed engine piston question

[zslave]

After much diagnosis and disassembly I have found that I have a chunk missing from the top of #5 piston likely due to the blown head gasket. I have assembled a pile of parts to put it back together but I cant find the same piston as OEM. The one I ordered is a sierra part# 18-4173, which has a shorter piston skirt but is the correct part for my engine. I'm only going to replace the bad piston and am unsure of this one. From what I can find, there is an "old" and "New" piston for this motor. anyone know if they weigh the same, and can I mix the new one with the other 7. other than the piston, the engine is spotless and fairly low hour. Any advice or help would be appreciated. I want to get it back together before it gets really cold here, but this is really holding up the progress. Thanks. Chris

 

[achris]

Re: 96 5.7 carbed engine piston question

Got a serial number for your engine?

 

[Bondo]

Re: 96 5.7 carbed engine piston question

After much diagnosis and disassembly I have found that I have a chunk missing from the top of #5 piston likely due to the blown head gasket. I have assembled a pile of parts to put it back together but I cant find the same piston as OEM. The one I ordered is a sierra part# 18-4173, which has a shorter piston skirt but is the correct part for my engine. I'm only going to replace the bad piston and am unsure of this one. From what I can find, there is an "old" and "New" piston for this motor. anyone know if they weigh the same, and can I mix the new one with the other 7. other than the piston, the engine is spotless and fairly low hour. Any advice or help would be appreciated. I want to get it back together before it gets really cold here, but this is really holding up the progress. Thanks. Chris

Ayuh,.... The actual Cause of yer issue is more likely Detonation, which burnt the top off the piston, 'n blew the head gasket,...

A Lean condition is the #1 cause, with the stuff they call gasoline these days,...

When ya get it back together, make Sure the fuel system is up to snuff,...

Btw,.... Bring yer old piston to an automotive parts house, or yer GM dealer to find a exact Matchin' piston,....
There are part numbers on 'em,...

 

[superbenk]

Re: 96 5.7 carbed engine piston question

That seems like the kind of thing you'd want to make sure was a matching set.

 

[Volphin]

Re: 96 5.7 carbed engine piston question

It is critical that the piston match the others. If you used one piston that was different, you will cause destructive vibration throughout the rotating assembly that will cause other parts to fail. Bondo is correct. Any GM dealer can get you that piston and ring assy. Better pick up a carb rebuild kit too. You were WAY to lean.

 

[zslave]

Re: 96 5.7 carbed engine piston question

got a serial number for your engine?

0f772664

 

[zslave]

Re: 96 5.7 carbed engine piston question

If I go with an automotive piston, will the compression ratio be the same? I have the casting/part #10128213 and will hopefully be able to get one locally

 

[Bondo]

Re: 96 5.7 carbed engine piston question

If I go with an automotive piston, will the compression ratio be the same? I have the casting/part #10128213 and will hopefully be able to get one locally

Ayuh,... The piston is within industrial tolerances, if the Part Number is the same,...

They All came from GM in the 1st place,...

 

[zslave]

Re: 96 5.7 carbed engine piston question

That was a dumb question on my part, of course the compression is the same. if only the New piston matched the old. For some reason my local delco warehouse cant get the one I had and the replacement from Napa/sierra is different. Off to some other parts stores. Thanks for the advice.