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Thread: 1968 S engine rebuild - seeking wisdom

  1. #1
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    Hi, I have a 68 s motor that has been completely rebuilt. The engine has not loosened off after being started a few times, and idles ok. However when the engine is turned off it spots instantly. Is this common in newly built engines? I am expecting not. The engine has a reduced weight flywheel but I suspect this is not a material factor.

    There is good oil pressure, and both banks are wet under the rocker covers ( near side is dryer than the far side)

    Currently looking to pull engine back out again

    Grateful for opinions, other shared experiences
    Last edited by Richsmith901; 03-23-2018 at 11:21 AM.
    Rich
    68 911S
    mbr. 2393

  2. #2
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    No wonder it's trying to seize... you're running no belt.


    After warming up pull all of the spark plugs and test your breakaway torque at the crank. (Put a torque wrench on pulley bolt and determine at what torque setting the crankshaft finally rotates.)

    Then do it again when completely cold and report the numbers.

    Not All-Conclusive but will provide some data for an opinion.

  3. #3
    Rich, what is the problem? It leaks oil?
    1966 911 #304065 Irischgruen

  4. #4
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    “spots” = “stops”.

    At least that’s what I took the liberty of assuming?

  5. #5
    Senior Member NZVW's Avatar
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    Quote Originally Posted by Frank Beck View Post
    “spots” = “stops”.
    My engine "stops" when I turn it off,, never really considered it an issue.

    Nice engine by the looks though and would be a shame to have to strip it down.

    Clarify the "spots" and Im sure the 'wise' will have a few suggestions.

    PS I was in Sevenoaks in 87 when it became just Singleoak after the "storm"

    Mark
    Last edited by NZVW; 02-22-2018 at 08:25 PM.

  6. #6
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    Frank's advice is good, go with that. You might also pull all the spark plugs and rotate the motor by hand. The motor should turn over easily. Any stiff resistance indicates a real problem. My father-in-law built his own tractor motor. He had me paint it and I had to rotate the motor and it was harder than hell to turn. I told him he sized his main and rod bearings incorrectly. And even if it ran, it wouldn't have any oil clearance and would ruin itself quickly. He didn't listen to me and put the motor in the tractor anyway. IDIOT! Still waiting to hear the upcoming Trainwreck. There's not a whole lot I can do for the guy, he's got to help himself. Unfortunately he's family.

  7. #7
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    Hi

    Frank is correct, spots = stops.

    My garage now has the engine back out again, they will be back on it on Tuesday. We should get torque measurements from the cold but not hot engine. Unfortunately the engine was already on its way out at the point I sent the message.

    Are there ‘common causes’ for a tight engine, i appreciate that each engine can have its own unique issues.

    What would be a normal range for the torque with plugs out?

    Many thanks Rich
    Rich
    68 911S
    mbr. 2393

  8. #8
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    Quote Originally Posted by NZVW View Post
    My engine "stops" when I turn it off,, never really considered it an issue.

    Nice engine by the looks though and would be a shame to have to strip it down.

    Clarify the "spots" and Im sure the 'wise' will have a few suggestions.

    PS I was in Sevenoaks in 87 when it became just Singleoak after the "storm"

    Mark
    OneOak or SingleOaks just doesn’t have the same ring to it..
    Rich
    68 911S
    mbr. 2393

  9. #9
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    Important to isolate exactly where the problem is as you're disassembling. (Cams, IMS, pistons, crank.) More than likely mains. Good luck with that.


    "spots"... still laughing... Was really hoping someone would recommend a feminine napkin.

    Surprised you guys didn't connect the dots. Although I've never heard the term before, "engine has not loosened off" was the tell.

  10. #10
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    Quote Originally Posted by Gearby View Post
    Any stiff resistance indicates a real problem. My father-in-law built his own tractor motor. He had me paint it and I had to rotate the motor and it was harder than hell to turn. I told him he sized his main and rod bearings incorrectly. And even if it ran, it wouldn't have any oil clearance and would ruin itself quickly. He didn't listen to me and put the motor in the tractor anyway. IDIOT! Still waiting to hear the upcoming Trainwreck. There's not a whole lot I can do for the guy, he's got to help himself. Unfortunately he's family.
    Don't be short sighted; opportunities like these usually take a well engineered and cunning plan. You've been given a gift! Use it wisely in the future.

    (Personally, I look forward to the day when my son in law thinks he's the smartest one in the room. That's when the real games will begin.)

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