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Piston problem

Jc cooper

Second gear fun!
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Has anyone ever heard of a forged .30over in 440 collapsing in skirt by .008 due to detonation supposedly , need input from engine gurus , head gasket blown both sides major blow by all started when number 5 porcelain blew out and went downhill fast less than twenty hours on it , up to my ears in alligators,
 
If you can post some pics, it would help! Sounds like more than one thing wrong.
 
Oh boy....sorry for your troubles Jc. I am not one of the 'gurus' which you seek but I'm very curious to know all your build specs and conditions in which this occurred.
 
No pics engine is out and back to builder 67 440 .30 over balance line hone arp in everything rods resized deep pan great temp and oil pressure Comp cams xe274h their adjustable rockers block decked heads resurfaced forged pistons flat top combustion chambers in .40 range to keep cr about 10to1 915 heads seats and stainless valves
 
Well off the top I'd say you 'should' of been okay detonation-wise with that cam at 10-1? It's not closing the intake super late but it's no stocker by any means. Not sure what "combustion chambers in .40 range" means, is it that the quench distance is .040? Either way, I could understand some pinging to let you know there was an issue? But that sounds like a major disaster. Like a parts failure or something wasn't put together right...
 
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You betcha!, but not in twenty hours. I had a 2295 trw .030 collapse a skirt by about that amount, but never had a blown head gasket, or any of the other problems. It was running elevens on pump gas, but turned a rod bearing, and I found the collapsed skirt on teardown. I bought one new 2295, and now running some 100LL as a sweetener for the pump gas.
Edit: 2295 is a small dome, trw claimed 11.5cr, really much closer to 10.5cr with my 906s.
 
Yea piston .10 below deck gasket.40 compressed with 915 heads builder assured all slugs were micred at install builder in business in Houston area for decades builds pro stickers as well as others not sure what happened, referenced you guys cause if it’s happened you’ll have heard it ,
 
What gas were you running? Alcohol free 93? 10%91? I don't know what is available in Texas.
 
Super she’ll premium with can of Royal Purple octane boost , builder wants to say too much timing or carb issues but 850 thermoquad is typically not lean in secondaries 6322 with tuning
 
Well off the top I'd say you 'should' of been okay detonation-wise with that cam at 10-1? It's not closing the intake super late but it's no stocker by any means. Not sure what "combustion chambers in .40 range" means, is it that the quench distance is .040? Either way, I could understand some pinging to let you know there was an issue? But that sounds like a major disaster. Like a parts failure or something wasn't put together right...
 
No pinging tried in in third gear 4/s lugging briefly no run on at kill bump key fired right off no indicators , but a mystery now !
 
Which came first, the chicken or the egg? Did it overheat, and then blow the head gasket? Did it blow the head gasket then overheat? Did the blown head gasket hydraulic a cylinder, causing the collapsed skirt? Was the collapsed skirt scored up?
Edit; was the collapsed skirt in the same cylinder as the blown out sparkplug? If it was, I would bet on a hydrauliced cylinder.
 
Two blown head gaskets is a big red flag to me for some sort of jetting/timing/octane issue.

Nothing to do with the piston skirts caused the gaskets to fail.
But, more than likely...... whatever caused the gaskets to fail is also the related to the cause of the collapsed skirt.
 
Which came first, the chicken or the egg? Did it overheat, and then blow the head gasket? Did it blow the head gasket then overheat? Did the blown head gasket hydraulic a cylinder, causing the collapsed skirt? Was the collapsed skirt scored up?
Edit; was the collapsed skirt in the same cylinder as the blown out sparkplug? If it was, I would bet on a hydrauliced cylinder.
What ya mean hydrauliced as with oil or something else no scores on piston and more than one no over heating
 
A hydrauliced cylinder is one that fills with fluid (fuel or coolant, in the case of an engine) that will not compress when the piston comes up on the compression stroke. Since the fluid wont compress , things bend, like pistons, connecting rods, valves etc. If the gasket blows damage is usually not quite so bad. Sometimes it just blows sparkplug pieces out. Fuel can fill a cylinder from a bad needle and seat, and an electric fuel pump. Coolant can get in thru a cracked head or block, or a bad head gasket.
 
Ok got u or maybe a leaking valley pan gasket due to to much machining
 
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