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Posts posted by RLWP

  1. On 15/10/2022 at 10:01, BEngo said:

    A standard three point bore gauge will also measure bore cylindricity.


    Technically, it doesn't. It measures straightness, roundness and concentricity. You can infer cylindricity from those figures, not measure it



  2. 15 hours ago, tommylad said:

    Many thanks for this BEngo - I did check and had (and still have) the 2 thou nip stated in the manual. Would be good to have cylindricity checked wouldn't it - although I guess it must be very close anyway else the bearing would've been tight when fitted.





    When working on experimental Stirling engines, we used to get the pistons checked by the metrology department, including cylindricity. They always pointed out, cylindricity is something they couldn't measure. 


    They can measure straightness, they can measure roundness, they can measure concentricity - but they had no 'cylindricity' measuring tool



  3. 14 hours ago, tommylad said:

    Yes thanks! Lots of lovely engines lying around! I particularly liked the NEW 6 cyl Riley blocks they're machining up!

    I've left the big end with them - Martin was very relaxed about the job, apparently the smaller the bearing the harder it is to remetal, so a JP one should be a doddle!



    They're impressive, those blocks. I didn't get them to unpack the crankshafts they had in a box



    • Haha 1
  4. 11 hours ago, tommylad said:

    Yes, I think that could be the best option for a more long term solution. When I rebuilt it I was only able to find one NOS big end bearing, which is still fine - but the repro one is really dissapointing. I guess these parts are principally intended for engines which run at the occaisional steam rally, not clocking up proper hours under load in a boat! Coventry boring remetalled my main bearings and although not cheap I was really pleased with the work they did - I'll give them a call.


    If that was some time ago, their whitemetalling man has moved to Coventry Classics.



  5. 18 hours ago, monkeyhanger said:

    Luckily I've managed to purchase a NOS bevel gear. Now I need to make sure I'm doing the right things when fitting it.


    Indeed. If it's a Marine JP you are going to have to take the flywheel off, and when you refit the gear housing you must get the fuel pump timing right



  6. 21 hours ago, monkeyhanger said:

    Thanks for that info. That was a page which was not in my manual, although there are no pages missing. Strange!



    Not really. There are several versions of the JP manual to trap the unwary. The reprints we sell have the plunger pump added at the back


    Wait 'til you try and work out a part number...



  7. 10 hours ago, Peugeot 106 said:


    Richard you've thrown me a bit with this as R&D have come up with different rated mounts front and back. I assume they've applied the 40% front 60% rear rule. Are you saying that this resultant "different resonant frequency" could be beneficial or are you WARNING against it?


    I'm warning against my idle, untested speculation.


    From the bits of theory I remember the engine is one mass/spring/damper system with the damping coming from mainly from the engine mounts. This system is going to have a (or more likely many) resonant frequency which is determined by all of those. You cannot change the mass, the springing and damping come from the engine mounts


    So, in theory, if you've got an engine that's going into resonance at an undesirable cruising speed, you could change the frequency by having different types of mount front and rear


    On the other hand - I'm speculating idly and R&D do this for a living. Go with the R&D set up



  8. 11 hours ago, IanD said:


    This means they have the same resonant frequency,


    Do they - and is that a good thing? After all, the engine can't wag at different speeds at each end of the block - it's a single solid item


    My guess (WARNING) is you end up with a different resonant frequency for the complete engine. And it might be that you completely upset the resonances in the setup to your advantage


    I've never done it, I do wonder if different stiffness mounts front and back would be a good thing



  9. 23 hours ago, Arthur Marshall said:

    Bit like everyone says about Listers. They go on for ever and nothing ever goes wrong...


    Oooh no - that's not right


    Things go wrong, and they still go on running


    Without engine mounts



  10. On 01/06/2022 at 09:51, Pluto said:

    Perhaps it would be best to go forwards environmentally to horse power, as the grass would be kept down naturally, and rose growers would have something to take home from their boat.


    OOh, no. Not horses


    Sheep! All we like sheep



  11. 4 hours ago, tree monkey said:

    I can take myself thank you very much


    Sure? And where have you been for the last couple of days...


    4 hours ago, BlueStringPudding said:


    Hmm... Monkey and strict instructions to see a doctor, eh...? It's not like he has previous with that.  🤔😶


    (If there's a) next time, I'll need to strap him to a sack truck, kicking and screaming,  and wheel him there myself 😉


    Hannibal Lecter style


    I think I've got a large dog cage somewhere, would that be useful?



    • Greenie 1
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