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Thread: Carb issues?

  1. #1
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    Carb issues?

    Have just tried to start the car after its been sitting for 18 months.
    New oil, filters etc, have primed the engine and seen oil come out the rockers.
    On starting up first got flames back out the carbs and would not start.
    Advanced the timing a little and first turn of the key the engine fires up and went straight to 3500/4000RPM!!!
    Throttle was not stuck open and as far as I know I have not adjusted any settings on the carbs (2 x Edelbrock 600cfm) since they were installed.
    The car is running an MSD Digital 6 Plus ignition.
    Any useful ideas as to whats wrong/needs looking at .
    Last edited by fabphil; 25-03-17 at 05:19 PM.

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    Did you retard the timing again after this happened? My first port of call would be to take the air filters off and make sure that the butterflies are properly closed, from there I would do the timing static. Basically it will only rev like that if there is an open throttle otherwise it doesn't get enough fuel in the engine to rev if the butterflies are closed.
    Just musing now but have you plumbed in the nitrous system yet? Could the extra fuel be coming from the secondary fuel line that you have for the NOS system?

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    Last edited by stilltrying; 25-03-17 at 09:06 PM.

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    Quote Originally Posted by stilltrying View Post
    Did you retard the timing again after this happened? My first port of call would be to take the air filters off and make sure that the butterflies are properly closed, from there I would do the timing static. Basically it will only rev like that if there is an open throttle otherwise it doesn't get enough fuel in the engine to rev if the butterflies are closed.
    Just musing now but have you plumbed in the nitrous system yet? Could the extra fuel be coming from the secondary fuel line that you have for the NOS system?
    Air filters are off.
    I retarded the timing a fraction and it went back to flames from the carb.
    I had to take the dissy out to fill the oil as the valve cover breathers are baffled.
    The engine oil was primed with a drill, dissy relocated and static timing done. (No.1 to TDC on compression stroke, rotor pointing to No.1 plug lead, install, rotor slight twist as gear engaged on cam).
    Have not put a timing light on it yet.
    The primary butterflies are closed but the secondary butterflies are slightly open.
    The throttle linkage is fully back on its stops and there is a little slack in the throttle cable.
    The nitrous has a secondary fuel pump but this supply is switched off via a separate switch and only feeds to the regulator at the moment.

  5. #5
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    Being as car was laid up for that long - carb gaskets drying-out/breaking down - air/vacuum leak within carb drawing neat fuel in to plenum with carb butterflies closed - if secondaries cranked open off 'stop' to get more air flow in to carb at low vacumn/idle rpm?
    Last edited by roscobbc; 26-03-17 at 01:27 PM.

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    Not disputing the above but curious as 18 months isn't a long time and I believe that the carbs were brand new not long beforehand, I would have hoped for a lot longer before any kind of breaking down of the gaskets but certainly worth looking into.

    Phil, you state that the rotor arm moved when the dizzy was finally located, this is fairly common, but did you turn the dizzy in the opposite direction to get the rotor arm pointing at number one lead again? I'm not sure what the static timing should be on your motor but as a guide I would do a static set up of something like 10 degrees before TDC and fire it up and see what happens before you try with a strobe light

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    Last edited by stilltrying; 27-03-17 at 04:39 PM.

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    Quote Originally Posted by stilltrying View Post
    Not disputing the above but curious as 18 months isn't a long time and I believe that the carbs were brand new not long beforehand, I would have hoped for a lot longer before any kind of breaking down of the gaskets but certainly worth looking into.

    Phil, you state that the rotor arm moved when the dizzy was finally located, this is fairly common, but did you turn the dizzy in the opposite direction to get the rotor arm pointing at number one lead again? I'm not sure what the static timing should be on your motor but as a guide I would do a static set up of something like 10 degrees before TDC and fire it up and see what happens before you try with a strobe light
    The gaskets are all good.
    Did find a vac leak- forgot to plug the port for the servo hose as I've now got an electric vacuum pump . Now plugged.
    Will re-check the timing, that will be later in the week.
    Thanks for the advice so far guys.

  9. #9
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    Quote Originally Posted by stilltrying View Post
    Not disputing the above but curious as 18 months isn't a long time and I believe that the carbs were brand new not long beforehand, I would have hoped for a lot longer before any kind of breaking down of the gaskets but certainly worth looking into.

    Phil, you state that the rotor arm moved when the dizzy was finally located, this is fairly common, but did you turn the dizzy in the opposite direction to get the rotor arm pointing at number one lead again? I'm not sure what the static timing should be on your motor but as a guide I would do a static set up of something like 10 degrees before TDC and fire it up and see what happens before you try with a strobe light
    Those blue supposedly reusable gaskets are the cause of many a jammed-open float valve - in my experience when they fail small bits brake-off and block stuff up - todays ethanol mixed fuel don't help matters

  10. #10
    Carburetion 'sucks' !
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    Quote Originally Posted by stilltrying View Post
    Not disputing the above but curious as 18 months isn't a long time and I believe that the carbs were brand new not long beforehand, I would have hoped for a lot longer before any kind of breaking down of the gaskets but certainly worth looking into.

    Phil, you state that the rotor arm moved when the dizzy was finally located, this is fairly common, but did you turn the dizzy in the opposite direction to get the rotor arm pointing at number one lead again? I'm not sure what the static timing should be on your motor but as a guide I would do a static set up of something like 10 degrees before TDC and fire it up and see what happens before you try with a strobe light
    Those blue supposedly reusable gaskets are the cause of many a jammed-open float valve - in my experience when they fail small bits brake-off and block stuff up - todays ethanol mixed fuel don't help matters

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