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Care to do a Video Diagnosis?
https://slantsix.org/forum/viewtopic.php?t=49292		 Page 2 of 2
Author:  olafla [ Sun Jul 15, 2012 7:52 am ]
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This link came up in another discussion concerning ignition. It may give you some input to understand some aspects of the Weber better, even if some members here don't share the article writer's enthusiasm for the reasoning and methods.

http://performancecarbscience.com/weber ... onversion/

Olaf
Author:  Reed [ Sun Jul 15, 2012 8:31 am ]
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Author:  wjajr [ Sun Jul 15, 2012 9:37 am ]
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From your original post, second video, are you changing distributor’s position during filming, or changing idle speed with idle adjustment to cause timing mark to run up & down ten + degrees? Also a constant illuminated timing light, and steady camera would be helpful along with commentary covering any parameters being changed so we can get a better read on what is happening in real time.

Also transmission cooler line looks twisted enough to restrict fluid flow to radiator. Perhaps you should fix that before transmission has a meltdown.
Author:  SlantSixDan [ Sun Jul 15, 2012 10:26 am ]
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Olaf's link has been posted and debunked in this forum before. Reed, good job hitting the highlights (or lowlights) of that link. It's not a question of "not sharing enthusiasm for methods and reasoning", it's a matter of objecting to articles containing numerous fundamental errors of fact.

Let's keep the good info flowing, folks!
Author:  olafla [ Sun Jul 15, 2012 5:19 pm ]
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Quote:
It may give you some input to understand some aspects of the Weber better
Quote:
As this article pertains to a Weber 32/36 on a Jeep, the small primary throttle bore and single idle circuit can make it quite difficult to idle without exposing the first progression hole, making it run rich all the time.
The quote above, that was taken from the article mentioned, may relate to a specific Jeep problem, but if it is the same problem that makes the Weber on jrdoj's SL6 run rich, it is relevant info.

Olaf.
Author:  jrdoj [ Sun Jul 15, 2012 10:13 pm ]
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Sorry for the delayed response. I work on Sundays...

Dan said:
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There's supposed to be a spring, and no, the answer is still that there's not supposed to be much of any play in the mixture screw.
I realize the spring is supposed to be there (and it is) - I just removed it temporarily to check for said play within the threading. This suggested a possible vacuum leak source, so we tried temporarily adding some teflon tape to see it would have any impact. It didn't. Anyone experienced this before? I've been careful to never overtorque that screw, so I'm not sure why this is happening. I suspected being given the wrong size screw, but have not heard back from Redline's terrible customer service. But enough about that...

Reed said:
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Have you verified that you aren't putting the rotor in 180 degrees off?
It wouldn't even run if I was that far off, would it? That said, I cycled the engine and made sure I was getting air pressure before the #1 cylinder peaked. So yes, TDC.

Thanks, Olaf, for posting that article. Even though it's apparently not entirely applicable to my situation, I think I understand the vacuum advance system a little better. Plus, it got me thinking...
Reed emphasized:
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The only thing you need to know to run a Weber carb with a slant six distributor is which port on the carb provides the ported vacuum signal. Hook the distributor up to that port and you will be fine.
Dan said, previously:
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Distributor needs to be hooked up to a port that has no vacuum at idle, and has vacuum above idle.
And as Olaf was reminding me:
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the small primary throttle bore and single idle circuit can make it quite difficult to idle without exposing the first progression hole, making it run rich all the time.
...is "idle" defined by the number of RPMs, or by the mechanical position of the throttle? In order to get my engine to run at all, I have to turn the idle screw about four turns in (well past the 1.5 turns max Weber specifies), causing it to run at about 1000-1200 RPMs, and my vacuum advance thereby engages as soon as I start the car.

So if the vacuum leak(s) is the culprit....
Reed said:
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A vacuum gauge is a very helpful diagnostic tool. The fact that the motor exhibits the same symptoms with different carbs suggests the problem is with something other than the carb.
I will look in to getting a vacuum gauge. I have no experience with one (as you may have guessed). If the vacuum leak isn't coming from the carb, the carb base, the manifold to cylinder head mounting points, or the vacuum advance pod, where else is there to look? (I should have asked this sooner.)

I really appreciate your time, gentlemen. Thanks so much for you input.
Author:  jrdoj [ Sun Jul 15, 2012 10:25 pm ]
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wjajr said:
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From your original post, second video, are you changing distributor’s position during filming, or changing idle speed with idle adjustment to cause timing mark to run up & down ten + degrees?
I'm advancing and retarding the timing by hand, with no specific number of degrees in mind. I'm just demonstrating how far out of wack the timing is by showing how far my my homemade timing mark is from where it should be (which is relatively close to where the missing timing tab would be up top).

wjajr said:
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Also transmission cooler line looks twisted enough to restrict fluid flow to radiator. Perhaps you should fix that before transmission has a meltdown.
Good eye. I don't think it's quite as bad as it looks there, but you're right, and it's something I'll fix once I'm actually using the transmission. :?
Author:  Reed [ Sun Jul 15, 2012 11:04 pm ]
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"Idle" in this sense is referring to the position of the throttle. I have never worked on a Weber so I can't say if four turns is excessive, but the throttle should be nearly closed at idle. The opening for the port to which the vacuum advance hose is attached should be completely above the throttle blade at idle.

A slant six will run with the rotor 180 degrees out of position. I bought a Volare once for cheap due to the previous owners giving it a tune up which included a new cap and rotor. They matched the plug wires to the cap terminals in the right position and order, but somehow managed to clip it onto the distributor 180 degrees off. They sold it to me complaining that it lacked power on the highway and got bad gas mileage. :roll:

If you can't get the motor to idle below 1000 rpm, I suspect a miss-timed motor and/or a vacuum leak. You definitely need a vacuum gauge and a timing tab to do more diagnosis. Why not make your own timing tab? In the short run, set the timing to where the engine makes the most vacuum at the correct idle speed. If you have no vacuum gauge, advance the timing as far as you can to keep a smooth idle at the proper idle speed. Neither of those methods is the ideal way to set your timing, and you should set it properly ASAP.
Author:  itlldo1 [ Mon Jul 16, 2012 6:19 am ]
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Check the 1st video-is the PCV valve loose in the grommet-I hear what I think is a vacuum leak at the front of the engine. Also-pull your plugs-from the tailpipe it sounds like you may have a miss . That could be caused by a bad plug, or wire, switched wire, valve too tight on that cyl. I'd also check the firing order of the wires in the cap. 1,5,3,6,2,4. Mike
Author:  olafla [ Mon Jul 16, 2012 7:28 pm ]
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Quote:
Plus, it got me thinking...
Excellent, look behind the words, and study the concept! The vacuum port issue has been heavily debated in several fora for many years, even more than SL6 pinging...

Q: Have you adjusted the valves recently? If not, you may want to do them, the procedure is very well documented, follow link in the engine FAQ.

Re: Tuning with a vacuum gauge; here is a nice interactive one, there are many more on the net.

http://www.secondchancegarage.com/public/186.cfm

More Weber tuning: http://www.classicinlines.com/WeberTune.asp

Olaf
Author:  jrdoj [ Mon Jul 16, 2012 9:48 pm ]
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Reed said:
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A slant six will run with the rotor 180 degrees out of position.
Just out of curiosity, is it more likely to run 180 degrees out of position than, say, 90 degrees out? There should be absolutely no reason it's out of position, but now you're tempting me to check.

itlldo1 said:
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is the PCV valve loose in the grommet-I hear what I think is a vacuum leak at the front of the engine
It's not loose, but it does make an annoying, rattly whistle. I'm pretty sure I got the right one, but I did plan to look in to it - maybe see if I can replace the grommet since it's pretty old and stiff.

Thanks for the suggestions/links, Olaf. Those will come in handy.

I have to leave town for a week soon, so I'm going to have to follow up on most of these procedures after I get back. Thanks for the help, guys (and gals, in case I didn't realize).
Author:  Reed [ Mon Jul 16, 2012 10:06 pm ]
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It is defintely more likely to run at 180 degrees out than at 90 degrees out. In fact, it likely won't run at all at 90 degrees out. 180 degrees out works because it fires the plug at tdc on the exhaust stroke. The motor will run lIke this, but very poorly.
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