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  1. #91
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by GtoGeoff View Post
    He says he has the 12v relay, post 77.
    No mention of a relay and post 85 & 88 confirm it doesn't lol

  2. #92
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    Quote Originally Posted by kavesh View Post
    There is a lot of talk about fuel contamination. Is there a simple enough way to test the fuel?
    Just put a litre of methylated spirits into the tank and drive it, if there is moisture in there it'll sort it out.

  3. #93
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    Quote Originally Posted by kavesh View Post
    Yes I hear you and damn your theory on fuel contamination makes me want to swear. I may be looking at fuel that appears to be clean but in reality it may be contaminated...
    Since I got the motor running I have run the tank to about a quarter and them filled up, ran to half tank and filled up again.
    I have been running unleaded fuel and used a fuel additive to protect my valves. I was told by a mate that rather not use the additive as my motor will not be doing very high RPM, nor will it be doing huge mileage. I am not sure whether this would mean that its safe not use the additive. I have also heard talk of a litre of diesel to a tank of petrol to protect valves. Would you agree with any of these?
    I use a commercial valve saver designed for vintage racing motorcycles if the heads havenít had new exhaust seats. We buy it in bulk and share it amongst a group of friends.

    Diesel is unlikely to help, probably just soot up your heads. In certain jurisdictions the only fuels now available are 95 and above octane. Some engines were set up to run on 87 back when that was ďstandardĒ and some folks donít want to retune, they add a slug of diesel to the tank and donít see a drop in performance. It often soots up due to incomplete combustion and would most likely fail emissions tests. Sometimes, in the short term, it may create an impression of smoother running. However, in the longer term, youíre up for more expensive and unnecessary decoking and cleaning of your pistons, valves and head and your plugs will also soot up faster. There is also consideration of the environmental impact that incomplete combustion of hydrocarbons has, itís poisonous and stinks.

    The British vintage motorist association (canít recall their exact name) commissioned some testing a few years ago and found that if valves and heads hadnít been reconditioned, that is they went from long term use of leaded fuel to unleaded without a strip down and clean, then they retained ďlead memoryĒ for a long time and so long as there wasnít high temperature/high rev running then valve savers were unnecessary in many vehicles. It came down to the quality of the head material; softer castings had recession without lead and good quality valve savers did help with those situations.

    These days if youíre doing any head work then itís a low marginal cost proposition to have hardened exhaust seats done at the same time if you have any valve recession/seat wear.

    None of these things helps with contaminated fuel though.

    You can buy fuel stabilisers, however, they need to be added before the fuel deteriorates. My experience of these has been that they are more something you add to the tank of a vehicle before laying it up for a period with just a small amount in the tank. You then drain all of this out and add a can of fuel just to get to the petrol station.

    Really the cheapest thing to do if you suspect contaminated fuel is to completely drain the tank into jerry cans, drop the tank and have it cleaned and relined etc then put fresh fuel in. If you had muck in your tank your engine will now run well, if not youíll still have the fuel.

    There are fuel test kits sold at some car part places but Iíve never used one.

    If you are tempted to try the methylated spirit trick then donít use ordinary shop stuff, this can be up to 35% water itself. Thereís stuff sold thatís 90%+ ethanol and also specific products that can be used, however, they all carry risks because they can dissolve up a massive amount of crud that can be sitting in the bottom of the tank all at once and spit it down the throat of the carby, this can cause very nasty effects.Also if itís this gelatinous gunk that Iíve seen several times it tends to stick to the tank so you only get a certain percentage out with each flush, which is why I suggested dropping the tank and giving it a proper clean.

  4. #94
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    Hq308,
    You are correct, no relay. I saw that he 'rewired' for 12v & assumed a relay was used.

    Kavesh.

    Water is heavier than fuel & sinks to the bottom of the tank. So it gets sucked up first. From your symptoms, I doubt that it is water or fuel quality. I was surprised at 1000 ohms for non-resistor plugs, would expect closer to zero. However, you might get that reading depending on how clean the centre electrode was when measuring.

    It might be worth buying new plugs. The '5' heat range you are using is the correct heat range.

  5. #95
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    I have not had a lot of time this week but I did a few things today.

    With the ignition on I checked the voltage to the cable going into the BAT terminal on the HEI. I got 11.93v, not quite 12v. How much of an issue is this?

    I then started the engine and she will not idle. At higher RPM she runs fine. I gradually brought the rpm down and gave it a shot of fuel with the accelerator pump using my finger nail. This kept the motor running momentarily. When she wanted to die, I gave it another shot of fuel and she continued to rum. Does this give us more clues as to the problem being the idle circuit.

    This carb has 67 jets and 45B primary rods. Probably a bit too lean for cruising. I was told that a difference of 31 between jets and rods for the 308 is good. Would you agree with that?

    While the motor was idling I sprayed some WD40 around the intake to see whether i had a gasket leak but that was fine.

    I have received my carb back, so will try that out tomorrow and report back.

  6. #96
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by kavesh View Post
    I have not had a lot of time this week but I did a few things today.

    With the ignition on I checked the voltage to the cable going into the BAT terminal on the HEI. I got 11.93v, not quite 12v. How much of an issue is this?

    I then started the engine and she will not idle. At higher RPM she runs fine. I gradually brought the rpm down and gave it a shot of fuel with the accelerator pump using my finger nail. This kept the motor running momentarily. When she wanted to die, I gave it another shot of fuel and she continued to rum. Does this give us more clues as to the problem being the idle circuit.

    This carb has 67 jets and 45B primary rods. Probably a bit too lean for cruising. I was told that a difference of 31 between jets and rods for the 308 is good. Would you agree with that?

    While the motor was idling I sprayed some WD40 around the intake to see whether i had a gasket leak but that was fine.

    I have received my carb back, so will try that out tomorrow and report back.
    11.93v should be enough but it would tell more of a story knowing the actual battery voltage at the same time. Would be good to know the voltages at the coil & battery while running too. I don't think your current idle issue is ignition related from the testing you've done but it would still be worth checking just to remove any doubt. It sounds like it's lean at idle so it'll be interesting to see how it goes with your carb back on.

  7. #97
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    When I put my carb back on the motor and fired her up, she was purring like a kitten. Happy days I thought.

    Went for a km drive yesterday and cruising was good. I did however, note that on deceleration going down hill that she was back firing through the exhaust. Lean condition or needs more timing?

    Sadly though, when I got off the highway, the erratic idle had returned.

    I do not believe it is dirt from the fuel as I have a large fuel filter before the pump and the bronze filter in the carb inlet.

    Could this be a fuel pressure issue. I am going to try and borrow a fuel pressure gauge to test what pressure the mechanical pump is pushing out.

    Just confirming some basics again, On the 308 with HEI, I have my plugs gapped at 1.1mm going to reduce to 0.9mm,

    I will confirm voltage with motor running, I assume I need to get a wire at the BAT terminal and hook it up to the multimeter. This will be a little tricky to avoid getting shocked.

    I shall report back soon.

  8. #98
    been here .......too long Smitty2's Avatar
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    ... please throw the 'bronze' inlet filter into the nearest waste bin
    and
    get a proper inlet filter. Either the genuine 'early' style paper one
    or the later style

    [img]https://quadrajetparts.com/images/thumbs/250_250/Q2254A-w600.gif[/img]
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  9. #99
    been here .......too long Smitty2's Avatar
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    ... please throw the 'bronze' inlet filter into the nearest waste bin
    and
    get a proper inlet filter. Either the genuine 'early' style paper one
    or the later style .. as pictured


    Q2254A-w600.gif

    Bronze???
    these are just rubbish.. and cut fuel flow dramatically...

    GHP-Q2252-400w.jpg
    Last edited by Smitty2; 29-03-2021 at 06:58 PM.
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  10. #100
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    Symptoms do point to excessive fuel pressure as a possible cause. No need or reason to reduce plug gap with HEI. I have run over 3mm plug gaps...just for the heck of it....

    Ran & started just the same....

  11. #101
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    Quote Originally Posted by Smitty2 View Post
    ... please throw the 'bronze' inlet filter into the nearest waste bin
    and
    get a proper inlet filter. Either the genuine 'early' style paper one
    or the later style .. as pictured


    Q2254A-w600.gif

    Bronze???
    these are just rubbish.. and cut fuel flow dramatically...

    GHP-Q2252-400w.jpg
    Damn, I did not realise the bronze filter would restrict flow. I understand the concept of filtration. But will ask anyway, with a large filter before the fuel pump, how important is the filter then inside the pump. In South Africa its not easy to obtain the paper filter. I bronze ones seem like a good wash with petrol and you good to reuse.

  12. #102
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    Quote Originally Posted by GtoGeoff View Post
    Symptoms do point to excessive fuel pressure as a possible cause. No need or reason to reduce plug gap with HEI. I have run over 3mm plug gaps...just for the heck of it....

    Ran & started just the same....
    excessive fuel pressure or not enough pressure?
    Point noted on plug gap

  13. #103
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    So I borrowed a fuel pressure gauge yesterday and hooked it up. The needle did not even move when the engine was idling.

    The gauge is for a high pressure setup so perhaps it would not work for what I am trying to do.

    How else can I determine whether the fuel pump is going bad assuming the gauge borrowed is too big to give me a reading.

  14. #104
    Senior Member BasicQ's Avatar
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    Quote Originally Posted by kavesh View Post
    So I borrowed a fuel pressure gauge yesterday and hooked it up. The needle did not even move when the engine was idling.

    The gauge is for a high pressure setup so perhaps it would not work for what I am trying to do.

    How else can I determine whether the fuel pump is going bad assuming the gauge borrowed is too big to give me a reading.
    Vacuum gauges used for tuning often double as fuel pressure gauges.

  15. #105
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    Quote Originally Posted by BasicQ View Post
    Vacuum gauges used for tuning often double as fuel pressure gauges.
    So just plug the fuel line into the back of the vacuum gauge and crank the motor for a few seconds?

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