995jim
Contributor
Posts: 877
Loc: Ohio
Reg: 12-17-06
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05-22-23 08:32 AM - Post#2858169
Hi, can a new air filter and scoop on top lead to plugs showing a rich mixture or are the weiand roots blowers prone to a rich environment during idle, or is it another cause. Engine dyno showed correct a/f without anything over the carbs, but now im left with this question.
Any thoughts?
Thanks jim
Jim 
65' Impala SS, 65' Belair, 89' Silverado Z71, 95' Silverado Z71, 12' Silverado, 15' Silverado LTZ, 16' Tahoe LTZ |
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bobb
Super Senior Member
Posts: 6305
Loc: paradise
Reg: 09-05-03
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05-22-23 08:42 AM - Post#2858173
In response to 995jim
can be. i have a ntk af monitor for tuning and i think it was well worth it.
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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995jim
Contributor
Posts: 877
Loc: Ohio
Reg: 12-17-06
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05-22-23 09:15 AM - Post#2858174
In response to bobb
Is a hotter plug a solution or does it complicate things. I am currently using the recomended plug for the head (AL 3923)
Jim
65' Impala SS, 65' Belair, 89' Silverado Z71, 95' Silverado Z71, 12' Silverado, 15' Silverado LTZ, 16' Tahoe LTZ |
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 Shepherd
Valued Contributor
Posts: 2972
Loc: Lake George, NY
Reg: 11-11-15
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05-22-23 09:40 AM - Post#2858176
In response to 995jim
If the plugs don't foul without the air cleaner set up, seems that is the source, maybe too restrictive? What carb/s?
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Tony1963
Frequent Contributor
Posts: 2246
Loc: Orlando Florida
Reg: 07-09-18
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05-23-23 05:04 AM - Post#2858195
In response to Shepherd
I was always taught that the air filter will restrict airflow and won't on its own richen the mixture. That's especially true on a fuel injected engine.
With the air filter new, there must be another issue going on.
| People fear change because it threatens what they know, or what they claim to know. |
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Shepherd
Valued Contributor
Posts: 2972
Loc: Lake George, NY
Reg: 11-11-15
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05-23-23 05:27 AM - Post#2858197
In response to Tony1963
Tony, as an extreme example, take an AFB carb, close the choke and see how rich the engine goes,
that restricted vacuum will enrichen the carb. Of course that doesn't seem to be that extreme in the op's case by his description, the air cleaner is affecting something.
Edited by Shepherd on 05-23-23 05:28 AM. Reason for edit: No reason given.
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Tony1963
Frequent Contributor
Posts: 2246
Loc: Orlando Florida
Reg: 07-09-18
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05-23-23 03:40 PM - Post#2858217
In response to Shepherd
Yes, understood. However, with the choke closed you still have adequate airflow upstream. A Chevrolet dealer once told me that a restricted air filter will lower power, but not make it run rich.
I suppose if it was completely plugged then yes.
| People fear change because it threatens what they know, or what they claim to know. |
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Shepherd
Valued Contributor
Posts: 2972
Loc: Lake George, NY
Reg: 11-11-15
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05-23-23 04:11 PM - Post#2858218
In response to Tony1963
Of course the degree of restriction here is the governing factor, a closed choke will pull addition fuel from the bowl, which is the function in a cold start. So in effect, it's like putting you hand over the carb intake, black smoke and stall. As we know, running rich is a skewed air fuel ratio, much less o2, compared to fuel.
Edited by Shepherd on 05-23-23 04:38 PM. Reason for edit: No reason given.
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bobb
Super Senior Member
Posts: 6305
Loc: paradise
Reg: 09-05-03
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05-25-23 08:34 AM - Post#2858311
In response to 995jim
i would try running without air cleaners for awhile. if your getting too much air restriction at idle, cruising speed with high vacuum will super rich. also check float levels... aint blowers great? gotta love um.
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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995jim
Contributor
Posts: 877
Loc: Ohio
Reg: 12-17-06
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05-26-23 06:20 AM - Post#2858362
In response to bobb
Yep, i will have time over the holiday weekend to experiment and forward carb specs to question posed earlier.
Thanks jim
Jim
65' Impala SS, 65' Belair, 89' Silverado Z71, 95' Silverado Z71, 12' Silverado, 15' Silverado LTZ, 16' Tahoe LTZ |
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995jim
Contributor
Posts: 877
Loc: Ohio
Reg: 12-17-06
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05-29-23 05:41 PM - Post#2858515
In response to bobb
one of the possible determining factors to this symptom is that the car is not yet road worthy, so it only gets started and run periodically. It is very close to hitting the road but back to the carbs,(3310)I checked the float levels and they are just at or below the screw port on the side. Not sure if an engine can burn off a carboned plug to a leaner color brown if a lean condition is made. I did run it without the air filters. I guess I should get a vac gauge and check the readings on the carbs as well.
Jim
65' Impala SS, 65' Belair, 89' Silverado Z71, 95' Silverado Z71, 12' Silverado, 15' Silverado LTZ, 16' Tahoe LTZ |
Edited by 995jim on 05-29-23 05:59 PM. Reason for edit: No reason given.
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Shepherd
Valued Contributor
Posts: 2972
Loc: Lake George, NY
Reg: 11-11-15
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05-30-23 02:03 PM - Post#2858548
In response to 995jim
Yes, if vacuum is low, you may be engaging the power valve too soon, depends on the vacuum the carbs are seeing and the power valve setting.
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bobb
Super Senior Member
Posts: 6305
Loc: paradise
Reg: 09-05-03
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05-31-23 08:31 AM - Post#2858566
In response to Shepherd
may even be a leaking power valve.
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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