alright guys i had a problem about 2 weeks ago had my number one piston crack a chunck about 1/2 wide and and 2 inches long on the outter side of the piston broke off exposing the rings... i sence have tossed new rods and pistons in the car new gaskets everything fired it up for about 3 minutes... oil is milky already so i take the plugs out crank it over a few times and just the number one piston is shooting out fluid like a pump... i wanna say that that chunck of metal poped through the heads and broke the water jacket in just the number one... not sure never had this happen before? looking for someoen who has...

i might just get a new set of heads but its running on a 383 stroker with a decent lift dont really have the money for a aftermarket set just yet...and not many stock heads will do the job i had the 76cc heads pnp with tripple springs on them... i have the stuff to do a pnp,valve and spring job again just gotta track down a decent set of pre 87 heads... any help would be great thanks guys

 

Sounds like there is a block problem for it to be squirting coolant, or possibly the head on that one side is shot. May I ask what the engine was doing when you broke the piston?? If you hit something then you will more than likely have damage to the cylinder wall or head, if you were spraying nitrous the block or heads maybe warped, which means you will need to deck the block or mill the heads.

Best bet is to take it apart and take it to a good machine shop where they can check for cracks by heating the block up (heating the block up will cause the crack to get red hot before the rest of the metal). But that is work for a professional to do and check out for you because there could be so much wrong with it.

If you live near Chicago Illinois I have a good machinist that does the work on the side, he used to own a shop but retired and took all the equipment home with him and does it out of his house.

Good Luck!!

 

well i swung the heads over to have it checked out... at the time i was just breaking in the motor driving it very moderate not taking it above 5,000 rpm and the nitrous was hooked up but not being used of course till the motor was broken in... from what all i could tell when i tore it apart... the AC delco plug in the number one dropped the center porcelin out of it... bounced around a bit and busted the piston... it took a good chunk outta the outter ring of the piston off ill toss up some pics in a second... but i didnt find the rest of that piston... so had the heads at the shop as i was getting the new ones cleaned and they magnafluxed it...it cracked it right at the valve side... intake and exhaust it was spitting out both once i took the headers off... hard to see the crack and impossibal without the valves out of it... but my guess is when it broke off it shot up with the valve open and just crunched it and cracked the head... so i got the exact same heads... 76cc big port heads that im gonna port and polish tomorrow and toss some bigger springs and updated valves in... only reason im doing it is cause i have them laying around and i know it will support the flow i need for my 383... long story short i was in a rush didnt check the heads for internal damage just external which was fine... and now i gotta toss a new set on... so hopefully i will have it running this weekend... thank god the block was fine have some cash done in the machining in it.. and the motor didnt even have 150 miles on it when it broke the piston... ad ac delco was no help on that eaither... so im done buying there products... atleast new ones...

 

i really want to get a set of AFR 210cc but they dont make the cumbustion cahmber size i want off hand they made it for the zz383-500hp motor but besides that i dont notice them for sale... so its a custom order int he 2 grand range... but id rather go all or nothing... no point getting a 1,000 dollar set of heads when i just will turn around and get the 2 grand ones the next year... but these stockers will do for now.... here is the pic of the piston damage

 

The piston failed first and took out the plug, not the other way around. That's damage I've seen so many times I don't want to even think about it any more. Cast or Hyper pistons run in extreme detonation or with upper ring gap too tight. That's EXACTLY how they fail, every time.

Top ring gap closes down from the heat or the gap just being too tight, it locks in the bore and the next time the piston descends from TDC it rips off a chunk of ringland above the top ring, always near the valve relief pocket on the side of the piston. Every time, just like clockwork.

You didn't find the piston chunks becuase they got mashed up into little pieces and flew out the exhaust. You see those little gouges on the piston face in that picture? That's chunks of your ringland that were getting mashed up in the quench area between the piston and head as the piston continued to go up and down. You'll see more marks on the head as well plus little chunks of aluminum that have "welded" themselves to the valves and valve seats.

BTW- this type of damage can happen in a matter of SECONDS at WOT. Last set of hypers I blew up were running just fine at the 1/8th mile mark but were blown to smithereens by the 1000' mark. I hadn't even pulled 3rd gear yet. When it happens you will usually know right away- it's be running strong one second, popping and stuttering the next. That's becuase the piston chunks hold the valves open before they all finally exit and also becuase the plug often gets destroyed in the process as well.

Also- those almost look like Keith Black hypers. If so, you MUST MUST MUST follow their recommendations on top ring gap. They require MASSIVE gaps compared to a stock piston or a forged high performance piston. Top ring gap around .032" for a street nitrous motor with KB Hypers is the spec. A typical pre-gapped ring set will have maybe HALF that much ring gap. Guaranteed engine damage if you do it wrong. GUARANTEED.

 

they are acctually hypermax pistons by dynagear... now owned by badger piston they are hypertec with a dome as you can see... i was using "total seal" file fit rings and it ran fine for the first 100 miles no problem... temp never went past 175 degrees had constant 60psi or more of oil pressure and it didnt rev past 5,000rpm... they were old pistons but in a box on a shelf for years... there is acttually only one set in stock left of that piston at badger and i wasnt going to buy the last set in the world so i upgraded to a TRW forged piston with forged 5.85 rods... they were huge back in the day before aftermarket rods flodded the market... a chevy diesel rod... and although i know the 6 inch is a great rod im still affraid of the pin being in with the rings... but i just finnished pnp a new set of 76cc stock heads for now and putting in the isky springs that cam with my cam studs and everything else hopefully get it up and running by sunday