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#1421
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Grivera,
If I wasn't confused before, I sure am now. Sent from my SM-G955U using Tapatalk |
#1422
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I've followed this thread..great thread with a great end. Finally!
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#1423
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Quote:
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#1424
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You've certainly been a good sport throughout this fiasco. I hope you enjoy your ride, and put many miles on it!
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"Those poor souls have made the fatal mistake of surrounding us. Now we can fire in any direction" 1970 Trans Am RAIII 4 speed 1971 Trans Am 5.3 LM7 1977 Trans Am W72 Y82 1987 Grand National |
#1425
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Question
So, I'm going to have to go through this whole thread to see who guessed the piston slap first so we can determine the winner. I will send the winner a Pontiac sign like I said I would. Hell, I'll even throw in some local Virginia beer. Hopefully we can all agree on the winner! Hahahaha!
I do have a question though. There seems to be some confusion if the bearing spun or not when it failed on the dyno. After reading the recent post, I do remember that it was discussed about the spun bearing. Has anyone heard of a piston skirt collapsing when a bearing is spun? Is that normal? What happens when a bearing is spun that could or would cause the piston to hit the head. Is that even possible? Considering that the knocking noise has been the same since when I first received the motor and stopped when that one piston was replaced, I would just like to get a better understanding of what happens when you have a spun bearing. Last edited by Va68goat; 09-23-2019 at 09:19 PM. |
#1426
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I thought it was determined that it didn’t spin a bearing???
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#1427
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Finally victory. Enjoy the ride.
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#1428
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I've been tuning in just about every day. Even made a post. Glad for everyone involved. I didn't know piston slap would sound that bad.
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Frank M. 75 Firebird 68 Firebird 400 RAIII 66 Chevy II 461 Pontiac in AZ |
#1429
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Just to say, the usual piston slap is different than what happened here, this was a collapsed skirt. And that would be why it didn't sound like piston slap, this was a knock. Slap is generally cause by loose piston to wall clearances, this was a gross clearance issue.
.
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#1430
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It seems there is some conflicting comments from the engine builder about the bearing failure. The damaged piston was from the same cylinder as the bearing issue on dyno before Joe received it. Coincidence? only if your from Iowa.
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#1431
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“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#1432
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__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#1433
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As far as collateral damage from a spun bearing, that's a theoretical debate that could keep this thread going forever. When a rod bearing spins inside the connecting rod, it rapidly self destructs due to friction and heat. During normal operation, the inside diameter of the rod's big end clamps the bearing halves in place (bearing crush). When bearing crush is lost for whatever reason, the inserts will spin inside the rod's big end. Loss of lubrication will also cause a spun bearing, when the friction wanting to turn the bearing insert overcomes the bearing crush keeping it stationary in the rod. Usually it makes a hell of a racket and the damage is limited to the rod and the crankshaft, unless the rod comes apart (thrown rod). Since this engine didn't throw a rod, the rod bearing would have had to do one of two things to damage a piston: 1: Rod bearing is destroyed enough that the excess slack between rod's big end and crank journal allows piston to hit the head during TDC. That would have left witness marks on chamber and top of piston. Should result in damaged piston crown and pinched #1 ring land. 2: Rod bearing gets hot enough to friction weld itself between crank and big end of rod. Rod is then effectively welded to crankshaft. Rod tries to whip around with crank, restrained only by piston. The piston is damaged from the abnormal forces. However, this typically tears the rod cap off or breaks the rod, resulting in total carnage. Motor would have had to be shut down just before it chucks a rod across the room, to damage a piston like this but not chuck a rod.
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 Last edited by chiphead; 09-24-2019 at 10:07 AM. |
#1434
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promptcritica,
The bearing was spun on rod #5. MidnightAuto, Thanks. I've driven that car for the last two days. It's great. I'm already thinking about what to do next to the car. tooski, I'm glad it worked out as well. It was great when Paul found the problem. When he disassembled the motor, he put one thumb at the top of the piston and another thumb at the bottom and when he rocked that piston back and forth, that sound was exactly what I have been listening to for almost 2 years. No better feeling when we installed the motor and started it and heard no knocking sound! 455GRIN, The #5 bearing spun on the original failed dyno which was the same cylinder as the damaged piston. hurryinhoosier62, It was great that Paul came here and fixed this motor. There is no doubt that there are plenty of shops that wouldn't have done that. As for what mgarblik said in his post about something getting into cylinder #5, that is just a possibility amongst a few other theories. Nothing has been confirmed that something fell into cylinder #5. I know there's a chance that it occurred but nothing has been confirmed. All that has been confirmed is that the bearing spun on #5 and the bearing was eaten up. Rod 5 and 6 were replaced along with the bearings. # 5 piston skirt collapsed, it was discovered, fixed and the motor is strong and knock free. Last edited by Va68goat; 09-24-2019 at 10:46 AM. |
#1435
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The engine sure sounds great now, congrats.
Any theories as to what would have happened if the engine was run with the damaged piston? |
#1436
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Gator67,
Thank you. Paul inspected and measured the #5 cylinder walls. He said it was fine. I had only driven the car for less than 250 miles since I received it. It was never driven hard during that time. |
#1437
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Theory only! It could have run like that for a very long time pissing off the owner every time he drove the car. Not the way to enjoy a great car like a GTO. I drove a Jeep 4.0L with the skirt actually broken off below the oil ring land. Found the entire half of the skirt in the oil pan when I finally took it apart after 2 years and 30K miles of hearing it knock. So the answer is we will really never know. Forged pistons are so soft and pliable, it may have just hung on there and operated indefinitely.
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#1438
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Some of you guys need to read post 1400 again. Paul goes into detail what he found and it will answer all of these questions.
He states right in there, the bearing wasn't spun. It was over heated and discolored the journal and the rod next to it but it did not spin inside the rod. The piston also never smacked the head and he explains why that never happened and couldn't have happened given the circumstances of this failure. He goes on to say that something entered the engine through the intake system and that's where the damage started. After all that Paul has done to make this right maybe it's about time some of you actually listen to what Paul has to say and drop the conspiracy theory crap. Bottom line is it's now fixed, Joe is happy and the engine runs as strong as ever. |
#1439
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FJ, this is where Paul previously said the bearing spun (Post 784):
__________________
Will Rivera '69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears '64 LeMans 400/461, #16 Heads, HR 230/236, TKO600, 9inch Rear, 3.89 gears '69 LeMans Vert, 350, #47 heads: Non-running project |
#1440
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Quote:
Sent from my SM-G955U using Tapatalk |
Closed Thread |
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