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engine won't start
https://slantsix.org/forum/viewtopic.php?t=35851		 Page 1 of 1
Author:  1967cuda [ Mon Jun 15, 2009 2:45 pm ]
Post subject:  engine won't start
I'd replaced the Holley 1920 that came with my car with a remanufactured one, (the one it came with was falling apart), and it ran poorly until it died one day. So I replaced the carb with a NOS Carter BBS. Ran for 10 or 15 minutes, rahter smootly, until the choke opened, then died. Rebuild the Carter, new needle and seat; ran for 10 or 15 minutes--smootly--until the choke opened and died.

I had the float mal-adjusted, so it was leaking quite a bit, (and I thought I didn't have the seat torqued tight enough, so I may have over-tightened it...) Then I re-adjusted the float correctly, but still won't start, and still leaks a little bit, seemingly from the front of the throttle shaft--it wasn't wet under the seat, so I've got my fingers crossed that I didn't strip it.

I don't know if the leak and the inability to start are related, as the non-starting problem existed before the leak.

I've done the fuel line mod recommended here, as well as replaced the spark plugs with the recommended NGKs. The rotor, cap and plug wires are all relatively new. I replaced the distributor with a remanufactured one before I put on the remanufactured Holley, so I think that works well enough, though I will replace that with a NOS eventually, too. I've checked for vacuum leaks by spraying starting fluid all around the manifold, and there doesn't seem to be any cracks on the intake floor beneath the carb.

I feel like I've come to an impasse... Thanks for your suggestions!
Thomas
Author:  ESP47 [ Mon Jun 15, 2009 3:49 pm ]
Post subject: 
Electronic ignition or points? If points, is your dwell within specs? I believe its somewhere between 41-45 or so.
Author:  65Dodge100 [ Tue Jun 16, 2009 5:22 am ]
Post subject: 
It sounds like it could be flooding. They can be hard or impossible to start once the plugs get wet. Have you checked if your spark plugs are wet? Can you smell gas all the time or hear it dripping into the intake after you stop cranking the engine?

If it’s not flooding, you could try pouring a thimble full of gas into the carburetor and see if it runs for a second - that would rule out any electrical problems.

Danny
Author:  1967cuda [ Tue Jun 16, 2009 10:24 am ]
Post subject: 
Quote:
It sounds like it could be flooding. They can be hard or impossible to start once the plugs get wet. Have you checked if your spark plugs are wet? Can you smell gas all the time or hear it dripping into the intake after you stop cranking the engine?

If it’s not flooding, you could try pouring a thimble full of gas into the carburetor and see if it runs for a second - that would rule out any electrical problems.
I'm still trying to understand the finer points of the carburetor: so if it was a flooding problem, would that still allow the car to run well while warming up, i.e. when the choke is still closed? And assuming I have the floats adjusted properly, is there another way for it to flood?
And I didn't think that the plugs being wet would cause such a problem--thanks for that info, I'll clean them up.

Also, it is a points distributor. I haven't checked the dwell; will do.

Thanks!
Author:  65Dodge100 [ Tue Jun 16, 2009 12:07 pm ]
Post subject: 
Author:  1967cuda [ Tue Jun 16, 2009 12:45 pm ]
Post subject: 
Author:  SlantSixDan [ Tue Jun 16, 2009 2:59 pm ]
Post subject: 
Quote:
So I have taken this carb apart several (three or four) times in order to check and adjust the floats. Is there a limit as to how many times one can disassemble and reassemble a carb before needing a new rebuild kit
Yes. The limit is once. The only way to assure an airtight seal between the top and middle and middle and lower castings is to use a new gasket each and every time. The inlet needle and seat needn't be replaced every time, nor the check balls or the accelerator pump plunger (though the latter will usually need to be oiled and flared if it is removed from its cylinder, and it should not be allowed to dry out).
Quote:
Also, how delicate is the needle and seat?
Not very. As long as you're not abusing it, it'll be fine.

Carburetor operation and repair manuals (and some training movies) are posted here for free download.
Author:  1967cuda [ Tue Jun 16, 2009 3:20 pm ]
Post subject: 
Thanks, Dan; I'll have to get a new kit, then.

Also, I already downloaded the PDF for the Carter BBS manual, and there seem to be some glitches with the file: the illustrations are overlapping the text. Any way to fix that? Watched the movies, too, thanks for those.

So I guess the re-use of gaskets may explain why it won't run after multiple dis- and re-assemblies. But I can't wrap my mind around why it seemed to work fine--after the first time I installed it, and after the first time I rebuilt it--while cold/warming up with choke closed, but dies when warmed up/choke open. My inexperienced intuition tells me that might be a vacuum leak. But all 3 hoses on the system are in good shape. Could it be the intake manifold and/or gasket? If so, what is the best way to test for leaks/cracks? I once tried spraying staring fluid all around; is there a better way to check?

Thanks!

Quote:
Quote:
So I have taken this carb apart several (three or four) times in order to check and adjust the floats. Is there a limit as to how many times one can disassemble and reassemble a carb before needing a new rebuild kit
Yes. The limit is once. The only way to assure an airtight seal between the top and middle and middle and lower castings is to use a new gasket each and every time. The inlet needle and seat needn't be replaced every time, nor the check balls or the accelerator pump plunger (though the latter will usually need to be oiled and flared if it is removed from its cylinder, and it should not be allowed to dry out).
Quote:
Also, how delicate is the needle and seat?
Not very. As long as you're not abusing it, it'll be fine.

Carburetor operation and repair manuals (and some training movies) are posted here for free download.
Author:  ESP47 [ Tue Jun 16, 2009 7:25 pm ]
Post subject: 
The leak areas would be manifold to head, carb base, carb sides, egr valve or egr block off plate on the opposite side of the intake and then wherever you have plugs screwed into the intake. So spray soapy water on those parts and then unplug the hose going from the pcv valve to the carb and use compressed air (not a ton of psi) and blow the air towards the carb. You should see bubbling if you have leaks. Thats just an easier way to do it with the motor off and you can see tiny leaks that you might not catch with your ear while spraying carb cleaner or whatever on it.
Author:  1967cuda [ Fri Jun 26, 2009 2:31 pm ]
Post subject: 
Hi all,
I have not had a chance to spend anytime in the garage since my last post, but I was reading through the manifold installation articles, and I realized something that had slipped my mind before: the heat control valve on my exhaust manifold does not work. The bi-metal spring is rusted, and just flaps around regardless of temperature. When I acquired the car, the spring was disengaged, so I clipped it back on, and observed the flapping/non-responsiveness to temperature variation, so then removed the spring again. If that is not working properly, what kind of symptoms might I expect?
Thanks,
Thomas
Author:  SlantSixDan [ Fri Jun 26, 2009 2:56 pm ]
Post subject: 
That's not causing your problem, but you ought to address it when you can. A working heat riser valve improves fuel economy and driveability, cold and hot.

Another possible cause for your car's appetite for carburetors: wet or otherwise contaminated gasoline, and/or wet or otherwise contaminated fuel filter.
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