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  1. #61
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by GtoGeoff View Post
    hq,
    Nothing wrong with my comprehension skills, but maybe you should brush up on your READING skills. You claimed in post 47 that there would be a minimal change in f/level, measured in thousandths, if fuel pressure changed. That is the part that was wrong. I gave you an example in post 49 of a 2 psi change [ 6 to 8 psi ] that changed fuel level 0.090".
    So is Doug Roe wrong too?
    I think most people would think 0.090" was a LOT more than minimal! 0.009" would be minimal.
    To put the numbers into more perspective, going from the initial 0.265" float setting with 6 psi to 0 psi changed the float setting by 34%. 34% ain't minimal...
    That's not correct, your example used a 0.090" different float setting to get the same fuel level, close but no cigar. You're example may or may not also include other variables such as different floats? Show me a real world example where ONLY the fuel pressure is changed and ALL other things are equal.

  2. #62
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    Quote Originally Posted by Smitty2 View Post
    yes.. it can
    end of a small screwdriver will do the job
    Thanks Smitty, that will work.

  3. #63
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    Quote Originally Posted by GtoGeoff View Post
    Kavesh,
    Are you getting nozzle drip at idle? Engine warmed up & running, use a torch to look at the tips of the brass tubes in the primary bores for any fuel dripping.
    As far as I know no, but I will confirm as described here Geoff.

  4. #64
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    hq,
    Read it AGAIN. Only fuel pressure was changed on a Chev carb, from 6 to 8 psi, 0.090" change reqd in float setting.
    Those numbers came from a chart titled: 'Relation of inlet size & fuel pressure to float setting'
    QJs have a very short float [ compared to say Carter/Edel ]. That is going to reduce the leverage that the float can exert on the n/seat against increased fuel pressure. So fuel level will rise more, relatively speaking, before the float can close the n/s. Hence the large numbers.

    Roe covers this aspect on p. 142: ' A float shape with more material in the fuel may help to...control fuel level'

  5. #65
    been here .......too long Smitty2's Avatar
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    .... I changed fuel pressure from 7psi to 14psi (via a pump change) and fuel level change was zero
    with the engine not running and at idle
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  6. #66
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    Well I would remove it & put in a glass case because it is very special.

  7. #67
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    One of my mates sent me his spare QJ to test on my motor. I had this on my 308 for a few weeks now and it was running great. Idled well and drove well.
    Yesterday I wanted to go for a ride and guess what the bloody erratic idle has returned on this carb. Thinking dirt may be present inside I stripped the carb and it was super clean, even ran wire through all the orifices.
    Put carb back together and its still running like sh&t.
    I used it a week ago and it was running like a champ. A week later and its not working like it should. Is this a pure coincidence that I have now experienced the same issue on 2 different carbs or is my problem elsewhere.
    Tests I have done and I will send links to the videos below, is closing the primary flaps and the idle smooths out and increases slightly. Put in drive and the erratic idle gets worse.
    I have adjusted the mixture screws and the drivers side I was able to bottom out and the motor did not stall, when I backed out the screw the motor magically increased RPM and idled smooth.
    https://www.youtube.com/watch?v=WSnqfFfRq9U
    https://www.youtube.com/watch?v=Pl9vtBegGy4
    https://www.youtube.com/watch?v=_4hrdZREmLU

    I cannot believe that a carb that was running strong suddenly develops a case of lack of fuel at idle. It has to be be something else. I am just getting frustrated with this. Please help and advise.

  8. #68
    Not the Kingswood! hq308's Avatar
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    Did you do anything else to the car around the same time you swapped the carb?

    I think you'd be unlucky to get 2 carbs with the same fault. Is it possibly an ignition issue? I'm thinking it could be something like a bad connection hidden in the wiring loom for example and you've disturbed it while changing the carb which has temporarily corrected the issue and now it has come back. It's not unusual for ignition problems to seem like a carb problem.

    If you haven't already it's probably a good time to go through the complete ignition system including the wiring. What distributor & coil are you running?

  9. #69
    casual poster STOKESY77's Avatar
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    Put a Holley Sniper on it and enjoy the benefits of an efi system that still has that Carby look It is also self learning.

  10. #70
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    Sounds like crud in the tank

  11. #71
    been here .......too long Smitty2's Avatar
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    cannot believe that a carb that was running strong suddenly develops a case of lack of fuel at idle. It has to be be something else. I am just getting frustrated with this. Please help and advise.
    seriously... I would be looking elsewhere-
    at fuel pressure and the fuel pump
    at the ignition and plugs etc
    at vac leaks (in any attached hoses/connections)
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  12. #72
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    Quote Originally Posted by hq308 View Post
    Did you do anything else to the car around the same time you swapped the carb?

    I think you'd be unlucky to get 2 carbs with the same fault. Is it possibly an ignition issue? I'm thinking it could be something like a bad connection hidden in the wiring loom for example and you've disturbed it while changing the carb which has temporarily corrected the issue and now it has come back. It's not unusual for ignition problems to seem like a carb problem.

    If you haven't already it's probably a good time to go through the complete ignition system including the wiring. What distributor & coil are you running?
    Absolutely nothing else was done when the carb was swapped with that from my mate.

    I have one of those large red HEI distributors which has the coil built into the cap.

    I have not messed around much after the carb started acting up yesterday. All I did was remove all spark plugs to see if anyone of them looked like it was fouling and they pretty much all looked the same. I used a multimeter to test the plugs and the all measured at 1000ohms, these are non resister plugs, NGK BP5FS.
    I am no sparky but will try and go through the wiring again. I must add here that when I did the truck restore about 8 years ago now, I went over every single wire and connection to make sure there was no damage to either.

  13. #73
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    Quote Originally Posted by Smitty2 View Post
    seriously... I would be looking elsewhere-
    at fuel pressure and the fuel pump
    at the ignition and plugs etc
    at vac leaks (in any attached hoses/connections)
    So i blocked off all vacuum lines and there was no change.
    I still have the mechanical fuel pump. If I rev it up a bit the engine is nice and smooth. I don't have a fuel pressure gauge to measure though.

    Please advise how you would go about testing the ignition system, I have the large HEI dizzy with built in coil in the cap.

    Thanks in advance

  14. #74
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    Quote Originally Posted by Horaldic View Post
    Sounds like crud in the tank
    I opened up the carb and there is no dirt at all in there. The tank was cleaned out in the past when I did the restore. Also have a large fuel filter before the mechanical pump.

  15. #75
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    Quote Originally Posted by STOKESY77 View Post
    Put a Holley Sniper on it and enjoy the benefits of an efi system that still has that Carby look It is also self learning.
    that is not even an option mate

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