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Idle Adjustment
https://slantsix.org/forum/viewtopic.php?t=52814		 Page 2 of 3
Author:  Reed [ Tue Jul 23, 2013 12:21 pm ]
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:lol: Good story!
Author:  Danarchy [ Tue Jul 23, 2013 2:43 pm ]
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Quote:
Cutlass was way too noisy for such a nice car...
Hey! I resemble that remark! :lol: I sold a 1964 Cutlass, to buy my 64 Dart...the Olds was only louder when the hood was up, may have been the 20 lbs. of insulation on the hood and firewall! :shock:
Author:  crater [ Tue Jul 23, 2013 3:28 pm ]
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took the advice from this thread and another suggesting an electronic thermostat for the choke and ordered that from Carbsonly. My stupid phone was cutting out so there was lots of back and forth, but Carlos was very helpful. Regardless of if it fixed the problem it is a nice inexpensive upgrade.
Author:  Reed [ Tue Jul 23, 2013 3:36 pm ]
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I agree. The CarbsOnly units are a great upgrade.
Author:  crater [ Wed Jul 24, 2013 8:05 am ]
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Getting the choke rod out of the way didn't change much. It was barely touching it with the throttle out, tho I did bend it a bit more straight and the choke seems to be working better(so thats good even tho the electric one is on the way). Still wont go below a 1k idle when warmed up. loosened the throttle cable, no difference. Its was not tight when the throttle stops, had a little give, so I didn't think that was the issue.

It seems the only contact the throttle on the carb has that stops it now is the accelerator pump linkage. And if thats all it can hit I'd suspect the problem is something else as at this point the idle should probably be in the ground if the screws are not making contact.

Guess I'll hunt around some more for any vacuum leaks. Anything else common that may cause a high idle like this?

I know exhaust leak was mentioned in regards to some noise in the video, but without an O2 sensor that shouldn't affect idle, right? Nothing metering that exhaust.
Author:  Reed [ Wed Jul 24, 2013 8:26 am ]
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What is your base timing set at? Too much initial advance can cause a high idle. Have you verified the accuracy of your timing mark?
Author:  Reed [ Wed Jul 24, 2013 8:31 am ]
Post subject:  Re: Idle Adjustment
Quote:
I also am wondering if the Idle is supposed to dip a bit when pressing the throttle?
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Heres a video of the tach and Vacuum gauge. Car is at temp from a nice drive around town. You can ignore that it is at 1200 and not 1,000
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http://www.youtube.com/watch?v=1jLe9FxVC5E
The idle speed should only increase when the throttle is operated. If everything is working properly the idle speed should not dip when the throttle is pressed. A drop in idle RPM usually indicates a fuel mix problem such as a vacuum leak causing a lean condition.

Have you verified the accuracy of that tachometer? It doesn't look like it is reading correctly to me. I don't like the several hundred RPM bounce it does when the RPMs are dropping to idle. Tachometers are supposed to be smooth and solid in their operation. Get a cheap second-hand handheld tachometer or borrow a friends and verify that the tach on your column is reading accurately.
Author:  crater [ Wed Jul 24, 2013 8:34 am ]
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Quote:
What is your base timing set at? Too much initial advance can cause a high idle. Have you verified the accuracy of your timing mark?
I have not. I was always told timing was the last thing to fiddle with after getting idle and mixture all set properly. I'll have to go get a timing light and try and find the timing marks.
Author:  Reed [ Wed Jul 24, 2013 8:51 am ]
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Quote:
Quote:
What is your base timing set at? Too much initial advance can cause a high idle. Have you verified the accuracy of your timing mark?
I have not. I was always told timing was the last thing to fiddle with after getting idle and mixture all set properly. I'll have to go get a timing light and try and find the timing marks.
Ohhhhh, that is bad advice. A few degrees change in base timing can change the curb idle several hundred RPM. You set the base timing FIRST, then you start messing with idle mixture and speed. THen once you get the idle mixture and speed where it needs to be you go back and verify the timing, and then adjust the curb idle mixture and speed, etc... repeat until perfect. Once the engine is running base timing is always first before idle speed and mixture.
Author:  crater [ Wed Jul 24, 2013 8:57 am ]
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Gotcha. Timing light on the way from amazon, should be here tomorrow.

If there's no TDC mark on the balancer(haven't looked yet as I'm at work) I pretty much have to pull the cover and find TDC, right?
Author:  Reed [ Wed Jul 24, 2013 9:02 am ]
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There will be a notch in the vibration dampener that is the timing mark. There should be a timing tab on the timing chain cover that indicates TDC as well as up to 20 degrees BTDC (that varies depending on the year of the motor) as well as possibly some degrees ATDC (again, depending on the year of the motor).

If you are missing the timing tab, there is no way to really accurately set the timing, You can ballpark it using a piston stop tool, and I can tell you how to do that, but you should check and see if you have a timing tab first.

For now, try turning the distributor a little bit counter-clockwise and then adjust your idle. By a little bit I mean less than ten degrees.
Author:  crater [ Wed Jul 24, 2013 9:04 am ]
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The tab is there, I remember seeing it. I think I just need to clean it off to see the marks.
Author:  crater [ Wed Jul 24, 2013 8:25 pm ]
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Tweaked the timing a bit counter clockwise as suggested. Seemed to speed up if anything. Decided to wait for more tinkering for the timing gun tomorrow. Might in fact just stop thinking about the idle till after valve seals this weekend.
Author:  Reed [ Wed Jul 24, 2013 9:34 pm ]
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Ack, sorry, brainfart. Turn the distributor clockwise to retard the timing and slow the idle.
Author:  wjajr [ Thu Jul 25, 2013 5:56 am ]
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I have been following along with your idle dilemma. As mentioned previously high idle can be a result of several conditions signally or in concert such as vacuum leak conditions, sticking carburetor parts, air/fuel adjustments, and incorrect timing. It seems as though you have investigated mechanical and vacuum plumbing problems listed above, except timing controls.

Back to square one; checking everything:
As Reed instructed, base or static timing must be set before other adjustments are attempted, but before base timing is set one has to determine if timing mark on vibration damper (pulley hanging off of crank shaft) has not spun out of position from failed rubber innards by using a piston stop to find TDC and making sure mark on pulley lines up with zero on timing tab.


One easily checked condition involving distributor adding additional timing even with weights freely moving is addition of vacuum advance because of vacuum can’s incorrect vacuum source at carburetor. Check to see if its vacuum line is plugged into a tap on carburetor that is located at an elevation above throttle plate that only sees vacuum when throttle plate is open, and none when closed. If its vacuum line is attached to a vacuum tap at base of carburetor, vacuum can is seeing high vacuum as soon as engine lights off activating vacuum advance can which runs up timing 6 to 15 or so degrees depending on unit over base setting.


Next check freedom of movement of centripetal advance mechanism or mechanical advance weights housed within distributor. If these weights won’t fully retract to resting position, that is, back to base timing setting, either from stuck weights or broken retractor springs, engine idle will never settle down because now you have a condition of base timing plus any advance degrees mechanical advance dialed in. To correct problem disassemble distributer clean and lubricate weight’s pivots.


Once you are sure all timing devices and reference marks are in order, move back to carburetor. Remove carburetor, make sure base of carburetor is dead flat with a known straight edge; if cupped use a #10 milbasterd flat file to dress base flat and remove filings.


While carburetor is off engine closely inspect it for throttle plate sticking in bore, and lose throttle shaft. If throttle plate is sticking, post again to us about it before reinstalling carburetor. If carburetor checks out, install it using a new carb to manifold gasket. Don’t over torque carburetor mounting nuts, or base will be cupped again. Check operation of carburetor’s linkages for binding, and correct any found.

with all parts back in place, rough set timing, crank up engine, and go about making adjustments; timing first, idle speed, air/fuel. Once static timing is set, it is a round robin back and forth dance tweaking A/F mix, idle speed. Remember idle speed is also controlled by timing advance, and you may have to revisit base timing setting, as a degree or two change can add or subtract up to several hundred rpm.
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