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Thread: Inconsistent idle

  1. #1
    Steve Gift
    Guest Steve Gift's Avatar

    Default Inconsistent idle

    This is a hard one to describe, but my 40hp type 1 is having some problems
    idling and/or running consistently. At the end of last year it was missing
    pretty bad, so I pulled the carb a few months ago, and rebuilt it using one
    of those rebuild kits. I also cleaned it out with carb and choke cleaner
    and blew all the holes out really well. I then put it back on, set the
    point gap, and timed it per specification (7.5 deg static btdc with a 010
    dizzy). I've been having some real problems getting the carb tuned right
    now. I'll think I have it, and then when I start it cold it'll start good
    on the choke, but when the choke is released it will idle real slow and real
    rough. Then i'll get it tuned again and it'll run fine for a while (both
    idle and on the street) and after it cools it will do the same thing all
    over. Any suggestions? The fuel tank and all lines were replaced,
    including a new filter. One other thing, the carb is getting really cold.
    Even on a pretty warm day like we had over the weekend (70F or so, and low
    humidity) it always gets cold and I can feel it and see a lot of
    condensation from the start of the venturi all the way down the intake tube.
    Is a carb supposed to always get this cold when it first starts, every time?
    I can see the condensation all the time now. I don't remember this before
    all the rebuilding I did, but I wasn't looking for it then either. What in
    the carb would be causing it to get this cold; is there something I have
    adjusted wrong? The heat risers are hooked up and are getting warm after
    idling for at least 10-15 mins, and even then the carb is still cold. Until
    any engine is warmed up, the heat risers won't be warming the intake
    manifold, so does everyone's carb get condensation on it for the first 10-15
    mins? Would this be causing the inconsitency I'm seeing, or should I be
    looking elsewhere? Thanks for any suggestions.

  2. #2
    Olli Lammi
    Guest Olli Lammi's Avatar

    Default Inconsistent idle

    >
    > This is a hard one to describe, but my 40hp type 1 is having some
    > problems idling and/or running consistently. ... <CLIP> ...
    > Would this be causing the inconsitency I'm seeing, or should I
    > be looking elsewhere? Thanks for any suggestions.


    You pulled the carb and now there is inconsistency. I'd check
    for intake leaks first. Intake manifold rubber boots and carburettor
    to manifold seal. I had a bad one when I did not remove the
    old carb-to-manifold gasket remains thoroughly. Ran well when
    cold and choke on and then all irrational when choke flap
    opened.

    --
    Olli

  3. #3
    Steve Gift
    Guest Steve Gift's Avatar

    Default Inconsistent idle

    Yeah, I thought of that too, and read some threads on leaks. I did make
    sure I cleaned the old intake gasket up real well, and the new one seems to
    make a pretty good seal. The throttle shaft does leak some fuel
    occasionally, but I sprayed some wd-40 around the area and listened for the
    engine rpm's to increase, but didn't hear anything. It does wick in there,
    but wd-40 wicks into most tight areas its sprayed. What does the diaphram
    and arm do that are attached to the rear end of the choke. There's a little
    plate on the backside of the carb held on by 3 screws. I changed that
    diaphram, with a new one from the kit, but something didn't seem to look
    quite right. What function does that perform, and could a poor install of
    it cause what I'm explaining?

    "Olli Lammi" <olammi@REMOVE.iki.fi> wrote in message
    news:c78qs8$o1n$1@phys-news1.kolumbus.fi...
    Steve Gift wrote:
    >
    > This is a hard one to describe, but my 40hp type 1 is having some
    > problems idling and/or running consistently. ... <CLIP> ...
    > Would this be causing the inconsitency I'm seeing, or should I
    > be looking elsewhere? Thanks for any suggestions.


    You pulled the carb and now there is inconsistency. I'd check
    for intake leaks first. Intake manifold rubber boots and carburettor
    to manifold seal. I had a bad one when I did not remove the
    old carb-to-manifold gasket remains thoroughly. Ran well when
    cold and choke on and then all irrational when choke flap
    opened.

    --
    Olli

  4. #4
    Bill Spiliotopoulos
    Guest Bill Spiliotopoulos's Avatar

    Default Inconsistent idle

    Carb getting cold has nothing to do with it's adjustment. The evaporation of
    fuel and the expansion of the air while traveling to lower pressure areas
    (bellow the throttle plate) absorb heat, and this is what makes you carb
    cold.
    The heat risers are meant to heat the inlet manifold, not the carb. The carb
    is heated a bit by the manifold as a side effect. You need warm air to the
    air filter to prevent the carb from icing.
    If the carb gets real cold to the point that is starts getting
    condensations, it will not idle properlly.

    Adjust the carb when the engine and carburator are completelly heated, at
    least after 30 minutes of hard driving, according to the required procedure.

    What carb do you have? Has this carb ever been runing properlly in the past
    on this engine?

    Bill,
    '67 Bug.

    Steve Gift" <gifty74@............> wrote in message
    news:e56dnd0gIJNpDArdRVn-hg@...............
    > This is a hard one to describe, but my 40hp type 1 is having some problems
    > idling and/or running consistently. At the end of last year it was

    missing
    > pretty bad, so I pulled the carb a few months ago, and rebuilt it using

    one
    > of those rebuild kits. I also cleaned it out with carb and choke cleaner
    > and blew all the holes out really well. I then put it back on, set the
    > point gap, and timed it per specification (7.5 deg static btdc with a 010
    > dizzy). I've been having some real problems getting the carb tuned right
    > now. I'll think I have it, and then when I start it cold it'll start good
    > on the choke, but when the choke is released it will idle real slow and

    real
    > rough. Then i'll get it tuned again and it'll run fine for a while (both
    > idle and on the street) and after it cools it will do the same thing all
    > over. Any suggestions? The fuel tank and all lines were replaced,
    > including a new filter. One other thing, the carb is getting really cold.
    > Even on a pretty warm day like we had over the weekend (70F or so, and low
    > humidity) it always gets cold and I can feel it and see a lot of
    > condensation from the start of the venturi all the way down the intake

    tube.
    > Is a carb supposed to always get this cold when it first starts, every

    time?
    > I can see the condensation all the time now. I don't remember this before
    > all the rebuilding I did, but I wasn't looking for it then either. What

    in
    > the carb would be causing it to get this cold; is there something I have
    > adjusted wrong? The heat risers are hooked up and are getting warm after
    > idling for at least 10-15 mins, and even then the carb is still cold.

    Until
    > any engine is warmed up, the heat risers won't be warming the intake
    > manifold, so does everyone's carb get condensation on it for the first

    10-15
    > mins? Would this be causing the inconsitency I'm seeing, or should I be
    > looking elsewhere? Thanks for any suggestions.
    >
    >

  5. #5
    Steve Gift
    Guest Steve Gift's Avatar

    Default Inconsistent idle

    The carb is a 28 PICT 1, and yes, it had been running pretty good. I pulled
    it to clean after I picked up a bad hesitation problem. I cleaned it,
    adjusted the timing, and swapped out all the old fuel lines. I used a
    rebuilt kit and changed most of the seals that had a replacement. The carb
    does not have any hot air going to it. The port on the old air filter was
    capped off, but it ran fine with it like that. Now, after the rebuild, the
    carb is noticeably cold, and I think that might be part of the rough idling.
    I checked the timing again last night and its dead on.

    After putting the old check valve in I did not see any gas coming out along
    the throttle shaft like before. It seems to run rich because I could smell
    fuel and exhaust much more than before. I can get the rpms to increase, and
    it doesn't have much of a problem doing that, and only a little black smoke
    to start. The plugs were pretty black with soot when I pulled them, and
    there was a lot of soot in the exhaust ports, more than I noticed before.
    Just seems like rich to me.

    "Bill Spiliotopoulos" <vspili..........m> wrote in message
    news:c7ai8c$16fkj$1@ID-54851.news.uni-berlin.de...
    > Carb getting cold has nothing to do with it's adjustment. The evaporation

    of
    > fuel and the expansion of the air while traveling to lower pressure areas
    > (bellow the throttle plate) absorb heat, and this is what makes you carb
    > cold.
    > The heat risers are meant to heat the inlet manifold, not the carb. The

    carb
    > is heated a bit by the manifold as a side effect. You need warm air to

    the
    > air filter to prevent the carb from icing.
    > If the carb gets real cold to the point that is starts getting
    > condensations, it will not idle properlly.
    >
    > Adjust the carb when the engine and carburator are completelly heated, at
    > least after 30 minutes of hard driving, according to the required

    procedure.
    >
    > What carb do you have? Has this carb ever been runing properlly in the

    past
    > on this engine?
    >
    > Bill,
    > '67 Bug.
    >
    > Steve Gift" <gifty74@............> wrote in message
    > news:e56dnd0gIJNpDArdRVn-hg@...............
    > > This is a hard one to describe, but my 40hp type 1 is having some

    problems
    > > idling and/or running consistently. At the end of last year it was

    > missing
    > > pretty bad, so I pulled the carb a few months ago, and rebuilt it using

    > one
    > > of those rebuild kits. I also cleaned it out with carb and choke

    cleaner
    > > and blew all the holes out really well. I then put it back on, set the
    > > point gap, and timed it per specification (7.5 deg static btdc with a

    010
    > > dizzy). I've been having some real problems getting the carb tuned

    right
    > > now. I'll think I have it, and then when I start it cold it'll start

    good
    > > on the choke, but when the choke is released it will idle real slow and

    > real
    > > rough. Then i'll get it tuned again and it'll run fine for a while

    (both
    > > idle and on the street) and after it cools it will do the same thing all
    > > over. Any suggestions? The fuel tank and all lines were replaced,
    > > including a new filter. One other thing, the carb is getting really

    cold.
    > > Even on a pretty warm day like we had over the weekend (70F or so, and

    low
    > > humidity) it always gets cold and I can feel it and see a lot of
    > > condensation from the start of the venturi all the way down the intake

    > tube.
    > > Is a carb supposed to always get this cold when it first starts, every

    > time?
    > > I can see the condensation all the time now. I don't remember this

    before
    > > all the rebuilding I did, but I wasn't looking for it then either. What

    > in
    > > the carb would be causing it to get this cold; is there something I have
    > > adjusted wrong? The heat risers are hooked up and are getting warm

    after
    > > idling for at least 10-15 mins, and even then the carb is still cold.

    > Until
    > > any engine is warmed up, the heat risers won't be warming the intake
    > > manifold, so does everyone's carb get condensation on it for the first

    > 10-15
    > > mins? Would this be causing the inconsitency I'm seeing, or should I be
    > > looking elsewhere? Thanks for any suggestions.
    > >
    > >

    >
    >

  6. #6
    jjs
    Guest jjs's Avatar

    Default Inconsistent idle

    In article <2cKdnehPqKeKQQXdRVn-vg@............>, "Steve Gift"
    <gifty74@............> wrote:

    > [...] The plugs were pretty black with soot when I pulled them, and
    > there was a lot of soot in the exhaust ports, more than I noticed before.
    > Just seems like rich to me.


    You did hook up the choke again, correct? The default position for it is
    closed (choke on). And you did not by chance use something like a wire or
    anything else hard to 'clean' the jets, did you? Doing that can open them
    up and cause a rich condition.

  7. #7
    Steve Gift
    Guest Steve Gift's Avatar

    Default Inconsistent idle

    Yeah, the choke is hooked up correct. I adjusted it and its closed when
    bone cold.

    I only used carb & choke cleaner and compressed air, no wires or anything.
    I examined all of the jets and there are no obstructions or anything like
    that. I'm pretty sure the float bowl is not overflowing now. I'll have to
    wait until I can get a good run out of it so I can adjust the carb and get
    it set the way it should be after this last disassemble.

    "jjs" <john@xyzzy.stafford.net> wrote in message
    news:john-0505040732270001@m-0-135.docsis.hbci.com...
    > In article <2cKdnehPqKeKQQXdRVn-vg@............>, "Steve Gift"
    > <gifty74@............> wrote:
    >
    > > [...] The plugs were pretty black with soot when I pulled them, and
    > > there was a lot of soot in the exhaust ports, more than I noticed

    before.
    > > Just seems like rich to me.

    >
    > You did hook up the choke again, correct? The default position for it is
    > closed (choke on). And you did not by chance use something like a wire or
    > anything else hard to 'clean' the jets, did you? Doing that can open them
    > up and cause a rich condition.

  8. #8
    Bill Spiliotopoulos
    Guest Bill Spiliotopoulos's Avatar

    Default Inconsistent idle

    A leaky float valve could lead to the symptoms you described.
    By the way, did you adjusted the idle mixture screw or just the throttle
    positioning screw?

    Note:
    7.5 static advance should be good for the engine to idle right, but this
    doesn't mean that timing is correctly adjusted.
    For the 010 you need a timing light to set the full advance at 3000-3500 rpm
    to about 30 - 32 degrees BTDC. With the timing light you can also check that
    your distributor is advancing properly.

    Bill,
    '67 Bug.

    "Steve Gift" <gifty74@............> wrote in message
    news:ze2dnb0nEMFAfQXdRVn-tw@...............
    > Yeah, the choke is hooked up correct. I adjusted it and its closed when
    > bone cold.
    >
    > I only used carb & choke cleaner and compressed air, no wires or anything.
    > I examined all of the jets and there are no obstructions or anything like
    > that. I'm pretty sure the float bowl is not overflowing now. I'll have

    to
    > wait until I can get a good run out of it so I can adjust the carb and get
    > it set the way it should be after this last disassemble.
    >
    > "jjs" <john@xyzzy.stafford.net> wrote in message
    > news:john-0505040732270001@m-0-135.docsis.hbci.com...
    > > In article <2cKdnehPqKeKQQXdRVn-vg@............>, "Steve Gift"
    > > <gifty74@............> wrote:
    > >
    > > > [...] The plugs were pretty black with soot when I pulled them, and
    > > > there was a lot of soot in the exhaust ports, more than I noticed

    > before.
    > > > Just seems like rich to me.

    > >
    > > You did hook up the choke again, correct? The default position for it is
    > > closed (choke on). And you did not by chance use something like a wire

    or
    > > anything else hard to 'clean' the jets, did you? Doing that can open

    them
    > > up and cause a rich condition.

    >
    >

  9. #9
    Olli Lammi
    Guest Olli Lammi's Avatar

    Default Inconsistent idle

    > Wow, thanks Scott. This may really mean something. Yes, the notches
    > are on the forward rim, and look like a "V" that would've come with
    > it from the factory. Like I said, 2 of them about 1/4" apart. On
    > the rearward half of the pulley, some PO pull a scratch mark at the
    > first of the two marks. I was *assuming* this was tdc, and the mark
    > to the right of that was 7.5 btdc. Damn, the more I'm looking at
    > those links you sent the more I'm thinking I'm set up now to be 10deg
    > btdc, maybe slightly more, static! My dizzy, the 010, says 7.5 btdc
    > static. Now I'm thinking the PO put that scratch mark on the pulley
    > to mark where he/she was supposed to time it at, static, so they
    > would remember which mark was the correct one. Lets hope this fixes
    > at least most of the idling and poor performance problems I've
    > having.


    Steve, I think it's time to really find out where your TDC is.
    The PO's scratch markings on the rim are not to be trusted.

    --
    Olli

  10. #10
    Olli Lammi
    Guest Olli Lammi's Avatar

    Default Inconsistent idle

    > I agree. So use the pencil in the cylinder trick and make certain
    > right?


    That is one easy way. Turn clockwise until the pencil stops rising.
    Mark that spot. Then turn the pulley over the TDC and turn
    engine counter clockwise and mark the spot where pencil stops
    rising again. The TDC is in the middle of those 2 spots.

    --
    Olli

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