Timing Advice Requested

Old Fogey UKOld Fogey UK Posts: 964Expert Adviser
I have a '34 Hudson 8 with a 254 motor.
The car only gets used on short runs because I live on the Isle of Wight (for those unfamiliar with British geography, this is a small island just off the south coast of England).
In consequence, I've had a problem with plugs sooting-up very quickly.
In an effort to prevent this, I've swapped to a hotter plug (Champion RJ12C) and only use 5% Ethanol fuel because British 10% is awful.
However, I'm getting an annoying exhaust backfire on the over-run after releasing the accelerator pedal and the plugs are still getting rather sooty.
This suggests to me that the ignition timing could need changing (presently TDC).
Please may I have some suggestions as to what might be a better timing point for my set-up ?


Comments

  • bob wardbob ward Posts: 1,356Senior Contributor
    The manual says 4.5 deg BTDC. I would use that as a starting point for experiment and try the car on your favourite test hill. If it pings reduce the 4.5 deg, if it doesn’t ping run the car like that for a while and see how your plugs look. 
    Lockyer Valley, Queensland
  • GeoffGeoff Posts: 4,570Senior Contributor
    Any ethanol is too much!  I doubt that ignition timing will  fix this. Bob, have you ever been to the Isle of Wight?  There are no hills.   Exhaust "popping" on over-run is usually caused  by too lean an idle mixture, but it could be the fuel itself causing the problem.    when the mixture is too lean it doesn't burn in the  combustion chamber properly, and accumulates in the exhaust system and   intermittently  explodes out the exhaust pipe.   Is the automatic choke adjusted properly, and the pipe from around the manifold clear?   What about the by-pass around the  intake?  If this is stuck in the summer position  then the intake will not be getting enough heat around it to vapourise the fuel when cold running.   You need to  go to  the mainland and give it a good run along the M1 perhaps!
    If you're stuck in a hole, stop digging.
  • Old Fogey UKOld Fogey UK Posts: 964Expert Adviser
    Thank you both.

    My car is an LTS and so has a manual choke, which is set properly for my Daytona Universal carb (Zenith 228 lookalike with an adjustable main jet).

    There is no bypass in the intake manifold; it's an ROC re-cast that just has an empty space inside and has a detachable blanking plate on the top where, presumably, the by-pass control would go - do I need to do something about that ?

    The ROC official guidance is to set the timing to the long arm of the H on the flywheel to cope with modern fuel - does that sound right to you ? I haven't done that yet as I wanted to check it out on this Forum first.

    Geoff - please don't ever say to an Isle of Wight local (they're known as Caulkheads) that we don't have any hills - they're very proud of our 850 feet high "mountain" !  :D
  • GeoffGeoff Posts: 4,570Senior Contributor
    Yes, that is the correct timing light setting, at idle.  The "new" manifold could be part of the problem, therefore not easily  overcome.  I understand that the main  keep-fit exercise on I.o.W. is running up and down the hill every time the tide comes in!
    If you're stuck in a hole, stop digging.
  • bob wardbob ward Posts: 1,356Senior Contributor
    Re the ROC manifold etc. I removed the stuck temperature control from my stock 35 H8 manifold and blanked off the holes etc, which I guess makes it now little different to the ROC manifold. 
    I also remade the gasket between the exhaust and inlet manifolds eliminating the exhaust gas circulation holes. 

    Lockyer Valley, Queensland
  • ratlee2ratlee2 Posts: 344Expert Adviser
    Depending on how much gas you use, you could separate the ethanol from the gas using water, agitating then extracting the water layer.
  • tigermothtigermoth Posts: 517Expert Adviser
    I have been burning ethanol gas in my 212 straight 6 for 20 years. The only issue I have ever had is a gas line that got soft and ballooned up.
    Regards, Tom
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