cylinder head temps

Discussion in 'Mech Tech' started by Dubs, Sep 7, 2020.

  1. Zed

    Zed Gradually getting grumpier

    Who knows? I imagine it's difficult setting the mixtures on a beetle? Carbs off for vent changes? I have the advantage in the bus of being able to leave the carbs and linkage fitted and balanced changing vents and of course mixtures are easy to access too.

    1700 character was really what I wanted from mine. One day I'll rebuild it properly, it would be difficult not to end up with 30-50 more HP just with a modest cam change and a little care. L.P.'s wasser effort was never as good as a 1600 and I got 135Hp out of that when it's revs were limited to 4,500 just with the right size valves, tight deck and correct CR for the cam. It was even better after I sorted the imbalanced flywheel and clutch and revved 1500 higher.

    I'd probably need a temporary engine meanwhile... I'll have to see what happens, it would be too easy to dive down the rabbit hole. :thinking:
     
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  2. Dubs

    Dubs Sponsor supporter extraordinaire

    I can change chokes in situ, and adjust idle mixture with a bit of knuckle scraping, so its not too much bother really.

    Its funny you mention balancing on your old 1700, as this one does feel imbalanced. I have put it down to me having to bodge a 215mm clutch to mate up to the early style release bearing in the bug box... maybe the centre pad isnt 100% in the centre. Bloody rabbit holes are tempting arent they!
     
  3. Zed

    Zed Gradually getting grumpier

    It was the wasser crank one that was out of balance after paying for it to be dynamically balanced. Sorted with a random flywheel and new clutch kit. Ridiculous!
     
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  4. Dubs

    Dubs Sponsor supporter extraordinaire

    Ahh yes, I remember now. Was the balancing done by the builder, or did he farm that out?
     
  5. Zed

    Zed Gradually getting grumpier

    I was the builder, I farmed it out. Bad decision as it turned out.

    I dismantled LP's wasser 1955 and replaced everything apart from the case and crank. You can't build a 76mm crank T1 with stock 5.4" rods, you have to use B pistons, 5.5" rods and a small shim. The cam, followers and oil pump had disappeared, the heads were crazy hemi cut efforts and it had the extra 0.1" deck. It also had the wrong oil pick up and all the bearings were wrecked. The case eas clearanced in the wrong places and the weirdly cut down rods with ovalled big ends were hitting the case roof. It wasn't hard to do a better job of it.
     
    Last edited: Sep 10, 2020
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  6. Yes, but apart from that, was it ok?
     
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  7. Zed

    Zed Gradually getting grumpier

    He'd dropped the crank into the case, chipping the corner off a small ledge that the wasser thrust plate tab hangs onto and bending the oil thrower washer.
    :lol:
    DSCF1710_zpscc1e541d.jpg
     
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  8. 77 Westy

    77 Westy Supporter

    Now you’re just being nit-picky.:)
     
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  9. He's never satisfied, that bloke :rolleyes:
     
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  10. Dubs

    Dubs Sponsor supporter extraordinaire

    Just in case anyone is interested... I have since changed to 28 vents, 115 mains, and thrashed it a bit more, and the temps only get above 100 if I stop and go in a shop for a bit, and then start it up again. But within a couple of minutes driving, it’s down to low 90’s again.

    on a cold morning like today, it only reached 80 before I got to work. I think am going to stop using it now until I get time to sort out a thermostat.
     
  11. Zed

    Zed Gradually getting grumpier

    What did you use to extend the wires?
     
  12. Dubs

    Dubs Sponsor supporter extraordinaire

    nothing. It was just long enough out the box.
     
  13. Zed

    Zed Gradually getting grumpier

    Tested it in boiling water? Is it a spark llug one.
     
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  14. Dubs

    Dubs Sponsor supporter extraordinaire

    Yes it is a spark plug one. I didn’t think of trying it in boiling water. Would that not bugger it up?
     
  15. Zed

    Zed Gradually getting grumpier

    No.
    It's just a simple 14 mm ring terminal used as a heat sink for the thermocouple which is the attached 2 core wire, probably about 2 ft long with s/s braid. From there to the gauge will be simple copper wire. The length of the braided thermocouple wire is crucial for the gauge to read correctly.
     
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  16. Zed

    Zed Gradually getting grumpier

    The other thing I've found now mine is getting on a bit, which is obvious when you think about how a thermocouple works is any poor connection messes the reading up though IIRC that makes it read higher.

    The connectors on my gauge are pins, not great, I must give them a squeeze instead of wiggling the wires.
     
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  17. Dubs

    Dubs Sponsor supporter extraordinaire

    Ah, I see. :thumbsup:

    I will try that tomorrow tea break then. I have also just ordered a cheaply meat thermometer, so will treble check with that when it arrives.
     
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  18. Dubs

    Dubs Sponsor supporter extraordinaire

    Well, the boiling water test showed 53 on the gauge :eek:

    To be fair, it wasn’t quite boiling, as I had to decant it from the kettle to a small container, and then carry it from the office out to the car, then turn the ignition on and dunk the thermocouple, but I can’t see it cooling down 50 degrees in those few seconds.

    I will check again with my bbq thermometer when it turns up, but based on that test, it looks like my gauge is miles out..
     
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  19. Zed

    Zed Gradually getting grumpier

    :rolleyes:
     
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  20. vinnyboy

    vinnyboy Supporter

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