My Twin Turbo Build - Page 4

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  1. #46
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    Default secondary cam chain Fail

    Hi guys well i had a couple of hours to do a partial teardown of my engine and here is what i found.

    the secondary chain has stretched and broken it has no identifying marks on it whatsoever...the primary chain is a Morse.

    i believe the sprocket let go first and began bunching itself into and oval shape which stretched and broke the chain.

    when i look at the tool steel key it shows evidence of stress and trauma beyond a single event... the sprocket cracked and the key kept driving it until disintegration.

    Im no expert but The sprocket appears to be either Cast or powdered metal.

    the crank sprocket is supposed to be high quality but it has a definite chan wear pattern after only about 12 hours in service.

    4 intake valves kissed the pistons and closed.. 4 have slightly bent stems and remain open... i believe this damage was post event.

    Attachment 169649Attachment 169651Attachment 169653Attachment 169655Attachment 169657Attachment 169659Attachment 169661Attachment 169663Attachment 169665

    oh well need to order more parts

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  3. #47

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    I agree with your post mortem, Jonathan. That secondary gear looks suspiciously like a powdered metal piece. Can you get a better pic of the surface of the gear along one of the crack faces.

    The crank gear shows a heat treatment on the teeth, visible from the blued / rainbow colors around each set of drive teeth. That does not mean it is a steel gear it could be something else. In the pic I couldn't see tooling marks around the OD from machining the gear. Again it might be the pic but it also could be a powdered metal gear. Look at the keyway in the gear. If it is a smooth continuous square cut from front to back like a broach would leave it is probably steel. If it has a molded appearance at the front or rear of the keyway it is most likely powdered metal.

    Cloyes should still have their steel crank gears which are used on all versions of the engine 2V / 3V / and 4V. If they do not then the next best source in Boundry's Pump Division folks who make the aftermarket oil pumps. At the PRI show this year I saw billet steel crank gears which they made for Coyote's in their booth. The booth folks said they had them for ModMotors also. It might be worth a call. FWIW they ar 2x the Cloyes price but have added some nice design features to improve gear strength.

    Good adjustable steel cam gears are hard to come by since Cloyes stopped making them. I would check Michael at L&M and also Accufab to see if they have any alternatives. If they do not, then it might be worth the effort to ask Boundry about their willingness to build them. Worst case scenario it is always possible to go to an aftermarket sprocket manufacturer give him a stock gear and ask him to build some for you. If you do be sure to build them as 9-way Cloyes clones not the 7 way pieces that I believe are made in Australia. Use a good steel like 8620 and be sure to heat treat them after they are finished machined.

    Something to keep in the back of your head is the beating that a 2-step gives to valve train drive components. Instead of a smooth continuous pull the 2-step continuously shocks the drive chains and gears. That beating is savage and typically the root cause of failures like this one.


    Ed


    p.s. Here is a link to the Boundry site listing showing their crank gear => Boundry Crank Gear This is a 21 tooth gear like the 4.6 and early 5.4 engines use. The late GT500 engines used a 19 or 20 tooth gear to reduce the size of the exhaust cam primary drive sprocket. Ford wanted to reduce the valve cover height apparently for some in chassis fitment considerations. That meant a smaller primary drive gear on the exhaust and an associated smaller crank gear. Our engines use 21 tooth crank gears and 42 tooth cam gears. The Boundry piece is a 21 tooth crank gear — just what the Doctor ordered.

    In the FWIW bucket it is made of heat treated 4340 which is much tougher than 8620.

    p.p.s. I just chatted with Travis at Boundry. He said they have been looking at producing a steel 9-way adjustable secondary gear since Cloyes has stepped out of the market. I am sending him some stuff on the gears in the next few days so he can have a look at what it might take to make this happen. More to come ...
    Last edited by eschaider; 01-24-2019 at 11:55 AM. Reason: Added postscript

  4. #48
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    Default

    Hi Ed thanks for the very informative reply...I am in touch with Brandan at LM engines, I’m looking at best options for me.

    I do not use a 2 step just transbrake and right foot😄.

    Here is a clear pic.

    Best regards Jonathan
    Attached Images Attached Images  

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  6. #49

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    Looking at that pic, my bet is we are looking at powdered metal there, Jonathan.

    I was talking to Michael at L&M earlier today and he told me they were going to have the gears custom made for L&M. So that should take some sting away from the availability issue. I also had chat with Travis at Boundary today. I am going to be sending him a Cloyes sprocket for him to evaluate. I'd say there is a 50/50 chance that Boundary might add the gears to their product offerings. Near term Michael @ L&M would be the short way home.


    Ed


    p.s. To break one of those gears w/o a two step I would bet they were powdered metal possibly with the keyways cut after the gear was formed. If that were the case it could easily explain the failure. Two steps are a good thing to avoid if at all possible. The beating they give the valvetrain's chain drives is unholy.
    Last edited by eschaider; 01-24-2019 at 11:32 PM. Reason: Added Postscript

  7. #50
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    Default

    Hi Ed,
    i am reviewing a few options at the moment as to a way forward...evaluating a short term repair over a possible full rebuild with sleeves etc.
    i won't be going for the two step,, no need i already have more power than we can put on the ground, this new setup has been great i wish it had hung together longer as i will miss the second race of our short season due work and being broken.

  8. #51

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    Quote Originally Posted by Thunderbolt287 View Post
    Hi Ed,
    i am reviewing a few options at the moment as to a way forward...evaluating a short term repair over a possible full rebuild with sleeves etc.
    i won't be going for the two step,, no need i already have more power than we can put on the ground, this new setup has been great i wish it had hung together longer as i will miss the second race of our short season due work and being broken.
    These toys of ours always find the best ways to abuse us, Jonathan. In situations like you are experiencing, I usually find it worthwhile to step back take a deep breath and begin anew with deliberate decisions and steps to increase the reliability (and it goes w/o saying power ).

    Discretion might be the better part of valor this go around ...


    Ed


    p.s. I have some models for the cams ready this evening.

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