Olds 455 Broken Timing Chain...weird coincidence?
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Olds 455 Broken Timing Chain...weird coincidence?

  1. #1
    Junior Member
    Join Date
    Aug 2017
    Madras, Oregon

    Default Olds 455 Broken Timing Chain...weird coincidence?

    Hello all,

    First post here. Recently got a 1975 Spectra 18' with an Olds 455 with a Jacuzzi WJ pump. Boat has around 300 hours on it. Unsure of the history of the boat. As far as I know, neither the engine or pump have been rebuilt, but both seem to be in good shape. Has GM style Mallory HEI distributor, Edelbrock carb and manifold, but other than that, it seems stock.

    Quick background: Took boat out for the first time two weeks ago. Ran and drove great. Stopped at dock for lunch, key chain broke and ignition key fell in lake. Had to hotwire to get going. Kept jumper wire between batt and ign terminal on ignition switch on loose in case I had to shut the motor down quick. Was cruising along at about 40mph and jumper wire came loose and engine shut down like like I had turned the key off, which I functionally did. Boat quickly coasted to a stop. Reconnected jumper, cranked, but engine wouldn't start. Fiddled around for an hour on the water trying to figure out the problem. Couldn't figure it out and got a tow home.

    Once home I troubleshooted more thinking something was wrong with ignition system. Ended up discovering distributor rotor wasn't rotating when I cranked engine. Removed distributor, noticed cam wasn't spinning with crank. Took timing cover plate (not sure of correct term) off and peeked in at timing chain. Timing chain broken. Haven't taken off harmonic balancer so can't get a great look inside yet from timing cover plate. But, I think damage is limited to broken chain.

    My question is, what about the weird timing coincidence? I am doubtful it is a coincidence. Jumper wire came off and engine shut down and timing chain broke at the same time. Did something cause the timing chain to break after the engine shut down from ~4000rpm and boat coasted to stop? I never heard or felt any strange sounds as I was cranking the engine immediately after the shutdown so I don't think anything else is damaged. And I believe the 455 (stock, anyways) is a non-interference engine. I don't think water came in through exhaust logs and hydro-locked the engine. Exhaust flappers in good shape.

    Any thoughts are appreciated.


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  3. #2
    Senior Member SoldHondaBoughtHondo's Avatar
    Join Date
    Oct 2009
    Lake Havasu az.


    I was olds/chev/cad service tech for almost 15 years...the boat in my avatar..455 olds....cant ever remember a bbo losing a timing chain unless it was a plastic stock deal...oil pump drive ok? Hydrolock the motor cant hurt the chain. Maybe a pic of the damaged chain would help. When you pull the front cover there should be a big washer on the crank in front of the gear on the bottom..maybe mechanical pump arm came apart and stuck in the chain....maybe the bolt for cam gear/fuel pump drive came loose? Tear it down..you should find the problem.
    "A liberal paradise would be a place where everybody has
    guaranteed employment, free comprehensive healthcare, free
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    utilities, and only law enforcement has guns. And believe it or
    not, such a place does, indeed, exist: It's called prison."

    Sheriff Joe Arpaio
    Maricopa County Sheriff's Office

  4. #3
    Senior Member
    Join Date
    Mar 2009


    Has nothing to do with your engine (THAT is a bizarre coincidence!)....But I was just up in Sumpter, OR to see the Gold Dredge and the eclipse, and was reading the July issue of Air Classics....The article in there was about a B-17 with a long and varied history, but it is named....."Madras Maiden" and is at your airport in the Erickson Aircraft collection...I even looked up where Madras was in my Oregon Atlas to see it was just north of where I traveled years ago thru Prineville and Redmond.
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  6. #4
    Senior Member Untamed 777's Avatar
    Join Date
    Sep 2010
    Central Oregon

    Default Race at Haystack

    Hey Pinkie Drag boats at Haystack this weekend, get it fixed and bring it out
    Team Untamed 777 T/E

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