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  #16 (permalink)  
Old 03-24-2015, 11:32 PM
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The sellers name is't "Brian" is it. There's a thread on another board posted by a guy who got burned by "Brian" in N.C. Pistons are probably some cast "claimer" style pistons, and that one could't take the detonation. I am Butch/junior stocker.

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  #17 (permalink)  
Old 03-25-2015, 08:24 AM
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Quote:
Originally Posted by Jahblah90 View Post
I don't know how to tell the type of piston. All I know is the pistons are dome. And the guy told me it needed piston rings but didn't mention that the piston was jacked up. It was going to be disassembled anyway to figure out the specs for final compression. I have never wanted dome pistons to begin with so swapping pistons was not out of question. Just kind of blows if the guy KNEW and didn't say. Glad the wall isn't destroyed.
I bought once a 305 TPI long block and the seller said it has blow by and rings need to be changed, i tore it down to find 7 broken pistons
When i talked to the seller he asked if i find the problem and i told him what i found, he said that he had a 4-71 or 6-71 blower on top of it and factory cast pistons...
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  #18 (permalink)  
Old 03-25-2015, 06:11 PM
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No, the guy I bought the engine froms name is Jerry. But I'm in Jacksonville if that narrows down the "brian" list in NC lol But he DID say the truck was his son's originally sooooo, Maybe. I bought the engine from the dad...Mid-late aged man, maybe in his 60's. He seemed to be a really cool dude so I figured I could trust him.

Another re-ring horror story lol I'm passing on any more "engine needs rings" sellers. Or i'm going to start pulling heads before cash is even touched!
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  #19 (permalink)  
Old 03-25-2015, 11:54 PM
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. Yeah, if any hint at all that something is wrong with an engine, just start offering 'core' price for it...

. Don't think that's detonation damage... in the wrong spot... butted ring ends makes the most sense... I love high compression engines... would just put a new domed piston in and keep going... check gap in other top rings... inspect for shiny patches like that in other cylinders indicating rings were butting... check for any other pistons with broken ring lands... check for rod bearing damage/bent rod from locked piston... run some kerosene or other octane booster in Premium gas...

. 64cc, 70cc, 76cc heads?

http://www.summitracing.com/popup/ca...ion-calculator
.
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  #20 (permalink)  
Old 03-28-2015, 10:56 AM
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UPDATE: I decided to go pull the other head and rotate the engine over to get better looks at the pistons.

Here is a closer view at piston #2

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It had a few tiny dints in it, i'm assuming from valve damage.
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  #21 (permalink)  
Old 03-28-2015, 11:02 AM
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Pulled the left head off and #3 piston has the same type damage with dints in the head. Took a picture of the #3 chamber and the valves look exhausted.

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Cylinder wall isn't damaged and no other pistons or chambers are damaged. Still spins over very freely. I really do believe in respecting my elders but I honestly feel like cursing the old dude out. He could have been honest with me. I would have been a bit more prepared for the repairs instead of buying other crap. I was a few bucks short when I purchased this and gave him my word that I would bring him the rest later and I did. I was a complete stranger and could have just not took him the rest of the cash but I have integrity. Guess he doesn't.

Last edited by Jahblah90; 03-28-2015 at 11:10 AM.
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  #22 (permalink)  
Old 03-28-2015, 11:32 AM
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. Not valve damage... from the pieces of rings and pistons that were removed...

. Valves don't look damaged... there's just been some moisture/water in there that caused a little surface rust...

. What's the heads casting numbers(s)...?
.
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  #23 (permalink)  
Old 03-28-2015, 02:05 PM
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They are the hecho Mexican 993 heads. Port matched and such. But that makes me feel a little better knowing the valves weren't hitting the pistons. I had not plan to reuse the heads anyway.
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Old 03-29-2015, 12:26 AM
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Yeah, the dents on the pistons are caused by the pieces of the broken rings and piston ring lands being repeatedly mashed at TDC until they were broken into small enough pieces to go out the exhaust.

If I were to bet, I'd say massive detonation and the resulting runaway combustion heat caused the rings to run much hotter, causing them to expand more and closing the gap, so that the ring ends butted end wedged in the bore tearing one end of the ring off and the top ring land/piston top with it. In one of your pic's you can even still see one intact ring end right at the break point on the piston.

A 383 with that much dome and even a large 76cc head like the 993's is still over 11:1 compression, pump gas would kill it in short order.
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Old 03-29-2015, 06:37 AM
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crank damage ?

I have seen more damage on the bottom end when pistons are damaged, time to see if the crank is bent and conditions of the rods.
Time for a complete tear down and carefull inspection of everything.
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  #26 (permalink)  
Old 03-29-2015, 07:59 AM
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UUUUGGGGHHHHHH!!!!!!!!!! If the crank is bent, someone OWES me something! If nothing but an explanation. I borrowed money to buy this POS!!! I will get into the bottom end next Saturday, if not today. I'm going to give the guy a call today. Need to ask him a couple of questions.
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  #27 (permalink)  
Old 03-29-2015, 10:08 AM
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Why did you borrow money to buy something and not verify it's condition before purchasing? Sometimes people lie, sometimes they remember differently, sometimes they repeat what they were told, sometimes they make up stuff. There are no guarantees with the human factor involved.
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Old 04-02-2015, 04:51 PM
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Quote:
Originally Posted by Jahblah90 View Post
They are the hecho Mexican 993 heads. Port matched and such. But that makes me feel a little better knowing the valves weren't hitting the pistons. I had not plan to reuse the heads anyway.
Another attemp to make a sows ear (993 heads) into s silk purse. Send 'em to a recycler and start over.

Bogie
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  #29 (permalink)  
Old 04-03-2015, 11:40 AM
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. I get about 10.7 - 10.9 compression ratio depending on how far the pistons are below the deck... maybe 350 - 375 HP depending on cam... max power limited by head flow... definitely needed to be using octane booster in Premium gas or racing fuel... did you see what ring gap they were using?
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  #30 (permalink)  
Old 04-04-2015, 07:24 PM
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Quote:
Originally Posted by Jahblah90 View Post
UUUUGGGGHHHHHH!!!!!!!!!! If the crank is bent, someone OWES me something! If nothing but an explanation. I borrowed money to buy this POS!!! I will get into the bottom end next Saturday, if not today. I'm going to give the guy a call today. Need to ask him a couple of questions.
This is beyond frustrating. I have been burned many times, so I feel your pain.
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