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Catastrophic Engine failure. 454 gen 6

Old 07-12-2021, 12:16 PM
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Default Catastrophic Engine failure. 454 gen 6

Before I pull my engine and do the autopsy... Seeing what some theories are on what let go. Engine wouldn't rev past ~2,200 rpms, but seemed to run perfect up to that. 8* timing. Seeing how we launched and I had my wife and son with me I decided to just put up the river and anchor for a while. 8.5 mph up against the current for three miles. No issues. Sat for several hours and then putting back with the current at ~ 11mph and a loud bang from the bilge and silence. Engine died. I didn't even bother trying to turn it over. I knew it was catastrophic. I looked in the bilge and sure enough there was oil.
Up until this point I was running 160*, 50 psi oil pressure and 2,000 rpms. No alarms or any kind of warning before it happened. There's a small crack in my oil pan from what I can only assume is a rod coming through. I just finished rebuilding this motor and finally got everything dialed in. Or so I thought... I did all the work except the machining and have the pics to go back through and see what I did. The only thing I can assume is the rod bolts let go on the third or fourth piston or I dropped a valve and it got wedged. Any other guesses? I'll pull it in a couple of weeks, but for now here are a couple of pics and a vid of it running. Listen to the valve train. I didn't like it from the first start. Too loud for a hydraulic roller motor. It's the factory non-adjustable rockers and lifters. Torque to spec and call it a day. I was planning on putting an adjustable set in over the winter...https://youtu.be/KekmU_mr6PA





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Old 07-12-2021, 12:30 PM
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150psi oil pressure at 2000rpm??? 😳
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Old 07-12-2021, 12:41 PM
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Give us some history on why engine was rebuilt in 1st place and its overall condition along with any rigging/exhaust parts replaced too.
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Old 07-12-2021, 12:54 PM
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What were the rod and main bearing clearances set to ?
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Old 07-12-2021, 01:28 PM
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Originally Posted by underpsi68 View Post
150psi oil pressure at 2000rpm??? 😳
Originally Posted by SB View Post
Give us some history on why engine was rebuilt in 1st place and it’s overall condition along with any rigging/exhaust parts replaced too.
Originally Posted by F-2 Speedy View Post
What were the rod and main bearing clearances set to ?
Some crazy oil pressure huh? 50 psi... Engine came with the boat. Needed to be rebuilt. Tired and beat. Nothing in particular. Sent it to the machine shop. Cleaned, line bored, honed, new cam bearings. Crank polished. All the tolerances were in spec, but I don't remember off the top of my head. I have inner and outer gauges and measured everything. No plastigauge... I reused the pistons and rods as well as the lifters and pushrods. Cleaned all the parts well before reinstalling them. Topped the short block with L29 heads that I cut for posilocks. This is also an L29 block. 9.3:1 compression. I'm running a new/used mag cam.
It has a new full closed cooling system. Runs at 160-165 which I verified with laser thermometer. The exhaust manifolds, 3" spacers, risers and elbows are all less than 2 years old. Very clean. Now running antifreeze. Rebuilt the OE 9780s Weber carb a few weeks ago because I thought I might have had plugged secondary's. No difference. It has a new intake also.
I'm also wondering about hydro lock as a possibility, but I can't see how. New flappers and it was after driving for two miles while moving.
Last thing. I had two issues that I had to straighten out that might have added to the problem. 1. Less than 10 psi oil pressure on first start. I didn't install three galley plugs under the spider. Figured it out quick and installed them. 70 psi after I installed them. 2. I had a problem with my FWC. I was running at 210 because a hose was running to the top of my exhaust manifold instead of to my spacer. Fixed and 160 after.










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Old 07-12-2021, 02:14 PM
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Video is pretty noisy like its starving for oil up top, did you look at the crank and rod bearings after you noticed the lifter valley pugs missing ?
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Old 07-12-2021, 02:27 PM
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Originally Posted by F-2 Speedy View Post
Video is pretty noisy like its starving for oil up top, did you look at the crank and rod bearings after you noticed the lifter valley pugs missing ?
I didn't like the sound of the valve train at all. Sounded like a diesel. I wasn't able to pull the caps to look at the bearings. The motor was still in the boat. I just pulled the intake to reinstall the plugs. I saw the oil pressure was good so I just figured it was a noisy stock valve train. I have the exact same motor in my 69 Camaro, but I used Lunati lifters and adjustable rockers among a few other mods... Very quiet.


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Old 07-12-2021, 03:19 PM
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...
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Old 07-12-2021, 03:20 PM
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Oh, okay. I read about it in this book.
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Old 07-12-2021, 04:19 PM
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I missed something I think... I know payup asked about my cam from the notification email. That's Ultraslick cam lube. None of it was dry.
SB, book probably wasn't for me lol, but that about sums me up right now if it was.
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