well i ripped apart my old LG4 a few days back with my girlfriend and found out why it was running like crap.

sorry the camera didnt want to foucus too good.

but 3 out of 8 pistons are totalled, i blew off chunks off the tops and cant find the tops of the pistons that broke off.

 

2

 

3 last one

 

How big a shot were you spraying?

 

LOL none, that was an untouched LG4 from 83

 

So, now what?

Can we assume you're going to install a 4" bore kit?

 

Heh, even my L69 wasn't that bad...

And were did you find a girl into that stuff????

Find me one!!!

 

Well SOMETHING happened to those pistons!!!

Here's what I can tell you right from the get-go: Your top rings were gapped too tight. That's EXACTLY what happens to pistons when the top ring ends butt together- chunks of pistons above the top ring get ripped off exactly like that. The top ring gets some serious heat in it and the gap closes down (or the gap is just too tight to begin with). When the piston hits TDC the ring locks tight in the bore. The crank starts to pull the piston back down but the top ring don't want to budge. Everyting above the top ring starts to tear off. Seen it many times. This is POSITIVELY what destroyed those pistons.

Now for the $64,000 question: why? Either the top rings were just gapped too damned tight to begin with or there was something throwing a LOT of heat at the pistons- detonation being the A#1 culprit- nitrous or not. Detonation makes for BIG spikes in combustion temps. But so does running lean or over-advanced spark with or without detonation.

The GOOD news: a set of fresh pistons with properly gapped rings (for your application- N/A, blower, nitrous- they all need different gaps) will likely solve the problem forever IF the engine is running well, no detonation is encountered and the combo is generally well chosen with matching parts and adequately tuned.

 

If there was less carbon id say head gasket failure but since thier nice and carboned up (Serious detonation). The ring gap could be a possibility but what Ive seen it is causes more of a slanted wear pattern not just chunks ripped off the piston. Either way a rebuild or beef injection is nessasary.

 

this was a bone stock, never molested engine from 1983, everything was at stock settings. i think it was from always running 87 octane, but i always gave it regular tune ups and crap.

and i dont care this happened a year ago and i just now cracked her open, now the camaro has a built 355 in it.

 

BTW- you may want to take it easy on the Jack Daniels and beers when you get around to RE-assembly!! (backround of picture).

 

lol, na i just kept those from my 17th birthday in april. that was a fun night.

i turn 18 april of next year. :lala:

 

lol the chunks of the pistons most likely got ground up into a fine dust.. Have fun with that project! Good luck.