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Discussion Starter #1
Indeed, this is the reason for my 0 psi reading, My question is, should I re-use this piston? It's just a daily driver, and I dont want to go through the headache of pulling the crankshaft. I might add that the P79 that was on the block is shaved .040. The intake left a half-circle crease that is not longer than 3/8". The exhaust smacked a little harder, and left a crease about 7/16". I have another P79 head (I have lots of parts, 5 parts cars.) Would it be ok to just slap it on there? thanks.

-andrew
73 240z
82 zx
 

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Hi Andrew------------The real question here is actually what damage has been done to the engine that's not visible. IMHO, after an incident like this, you would be well advised to check the #1 connecting rod and its cap and bolts for damage. And, of course, the only way to do this is to tear the engine down. You can do this without removing the engine from the car. FWIW

Roadman
Gulfport, MS
 

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I'm really just trying to be lazy, but sue, me, it's gonna get cold outside awfully quick, and I still have a fuel problem to deal with, after I get this back together! The valves just barely kissed the piston, surely, that cannot be too much stress? Just looking for something to tide me over through the winter!
 

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Hi Andrew------------Yeah, I can understand what you mean about working in the cold. I'm sure you are aware that you can pull that piston without pulling the crank by loosening up the motor mounts and jacking the engine up far enough for the pan to clear. You'll need to pull the head in any case, which IMO is the major part of the job. Or you can roll the dice and replace the engine if it grenades, maybe with an L-28 turbo? Good luck!

Roadman
Gulfport, MS
 

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LOL, grenades, I like that term, as long as it doesn't apply to my stuff! :) I have the head off of the car right now, I just hate pulling oil pans. It doesn't look like it did any damage to the bore, so I'm thinking it will be ok.
 

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I unknowinly had valve float at high rpm's till one of my intakes hit a piston hard enough to knock the keepers out letting the valve drop only to be hit even harder which seriosly bent the valve and snapped the valve guide off. This was enough to keep it lodged and not drop all the way into the cylinder. I had the guide changed, stuck a new valve in and put Schneider valve springs on. Nothing else was done to the motor and it still runs strong.

On another motor I missed a shift(bad tranny), stuck it in second instead of fourth, I was turning 6500-7000rpm befor the shift. I would guess the rpms went to 9000. It jumped the timing chain bending all 6 intakes. These weren't as bad as the above one but the car had no compression. Again just changed the valves. Pistons are pretty strong and can take a little wack, they just don't like detonation.
 

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Discussion Starter #7
t4240z, that's what I like to hear! parts that can be whacked, and then not even dinked with, and re-used! Your story sounds worse than mine, you make me feel better :p
 

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years ago i had a 1600 vw engine that the piston ate an exhaust valve. i mean
big hole in the top of the piston. i was on a budget so i took the piston off
at the pin and went to the local junkyard and bought a used one
i didnt even put new rings on it. i just stuck it in there with a rebuilt head
and it purred like a kitten until i sold the car a year later
 
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