Yes, I realize that the location of the port doesn't mean anything, but every slant I have ever worked on (they were all automatics) had vacuum at idle, on a port at the base of the carb. Maybe the standards use ported vacuum?
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| Author: | jl737 [ Thu Mar 03, 2005 7:33 pm ] |
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Yes, that is the right port for the vacuum advance and yes there SHOULD be vacuum there. Some cars use ported vacuum for the advance mechanism and others use manifold vacuum. All slants I have ever seen have the vacuum advance port on the base of the carb and there is always vacuum there. |
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| Author: | SlantSixDan [ Thu Mar 03, 2005 7:40 pm ] |
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Wow, we're really getting some polarized extremes of opinion here. 737, you're right that some carbs use manifold and some carbs use ported vacuum, but a couple things to keep in mind: *The external location of the distributor vacuum port doesn't tell anything about whether it's delivering ported or manifold vacuum. It's a function of the overall carb design, i.e., where'd they decide to put that fitting on the outside of the carb! The placement of the other end of the port (above or below the throttle plate) determines whether there will be vacuum at the external port at idle. BUT, *If the throttle plate is opened further than the factory setting for any reason, or if the throttle plate no longer closes the way it was designed to (as for instance because of a worn throttle shaft or improper plate replacement after a shaft rebush job), then the presence/absence of advance vacuum will be altered. |
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| Author: | dvdart [ Thu Mar 03, 2005 7:52 pm ] |
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Slant6Ram I am getting a new PCV. I did not check the idle screw adjustment yet. SlantSixDan I will rework the fuel line. My car has an automatic and the points distributor has been swapped out with an electronic unit. Thank you all |
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| Author: | jl737 [ Thu Mar 03, 2005 8:06 pm ] |
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Yes, I realize that the location of the port doesn't mean anything, but every slant I have ever worked on (they were all automatics) had vacuum at idle, on a port at the base of the carb. Maybe the standards use ported vacuum?
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| Author: | Dennis Weaver [ Thu Mar 03, 2005 8:21 pm ] |
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...mine have all had no (or very little) vacuum at idle (and all automatics). But since I have not seen every 1920 in creation, I'm still putting my money on SSD's point.  D/W |
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| Author: | jl737 [ Thu Mar 03, 2005 9:00 pm ] |
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The ones I worked on all had 1945s. |
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| Author: | argentina-slantsixer [ Fri Mar 04, 2005 2:09 am ] |
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I'm going with dennis and dan, my cars have almost no vacuum at idle (very little amount) on the dist vac port. Go figure that 1 square mm opening below throttle plate ain't that much of an opening... |
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| Author: | Slant6Ram [ Fri Mar 04, 2005 6:26 am ] |
| Post subject: | Oh no! It's a can of worms! |
Quote: Slant6Ram, you're just not necessarily correct on this. One more time: depending whether the spark port is above or below the throttle plate by design on this carburetor, vacuum at idle may or may not be present.
I am not an authority on this. I am trying to offer my experience, but don't build any sky scrapers based on my limited knowhow. There are still many things that I don't understand.My understanding is that the port should supply a signal to the vacuum advance, off at idle, on at light trottle and then decreasing again at full throttle. Since some vacuum advance pods are adjustable, a weak signal/strong signal could work just like a on/off signal if the distributor is adjusted properly. You have opened a little can of worms, that requires some tests and research specific to your car. We can only guide you as to what to check next, and you will find your own solution. |
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| Author: | argentina-slantsixer [ Fri Mar 04, 2005 6:36 am ] |
| Post subject: | Re: Oh no! It's a can of worms! |
Quote: ... don't build any sky scrapers based on my limited knowhow.
 great principle statement, slant6ramon other subjects, I've been compiling and drawing advance charts for our recurve things. I don't know if argentinian P/N are the same as american, I don't think so. Will get in touch soon. Take care. Juan. |
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