influence on idle quality
Thread Starter
Racer
Joined: Jul 2006
Posts: 337
Likes: 10
influence on idle quality
OK, searched a while but found nothing that exactly answers this question:
Why do injector / carb cleaner additives transform my "OK, but with a come and go every few seconds roughness, 50 rpm idle speed fluctuation"...... to nearly perfect, smooth as butter???
I am curious what is happening chemically that corrects the idle, and what this exactly points to as the problem......carb, ignition, or maybe engine mechanical issue?
The engine is in excellent condition, great, nearly equal compression on all 8, all new ignition parts, rebuilt Qjet with no wear at throttles. Runs perfectly all the time, less the slight idle roughness, which always come back when I forget to add the injector cleaner after filling up with 93.
FYI, timing is set up per Lars, vacuum is great.
Thanks !!!
Why do injector / carb cleaner additives transform my "OK, but with a come and go every few seconds roughness, 50 rpm idle speed fluctuation"...... to nearly perfect, smooth as butter???
I am curious what is happening chemically that corrects the idle, and what this exactly points to as the problem......carb, ignition, or maybe engine mechanical issue?
The engine is in excellent condition, great, nearly equal compression on all 8, all new ignition parts, rebuilt Qjet with no wear at throttles. Runs perfectly all the time, less the slight idle roughness, which always come back when I forget to add the injector cleaner after filling up with 93.
FYI, timing is set up per Lars, vacuum is great.
Thanks !!!
Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
When you say "what is happening chemically" are you implying that it runs well while the cleaner is in and then returns to a miss when you go back to strait gas?
Carb cleaners/injector cleaners are cleaners. Some call them snake oil, but I have used them with success. I have also used SEAFOAM through the carb to clean out the carbon buildup.
Carb cleaners/injector cleaners are cleaners. Some call them snake oil, but I have used them with success. I have also used SEAFOAM through the carb to clean out the carbon buildup.
Thread Starter
Racer
Joined: Jul 2006
Posts: 337
Likes: 10
Yes, with the addition of these type of products, idle is perfect, all the time.......without, a bit rough.
I just rebuilt the carb (due to flooding problem) in late Jan. It is spotless, so these products have nothing to clean. These products alter the combustion characteristics of "straight" gas somewhat....IE easier to ignite, higher or lower flash point, octane is increased etc etc.
One or more of these is byproducts is helping out to create ideal ignition and eliminate the slight roughness.
I want to know why,exactly, these products improve the idle, and what problem they would point to.....IE maybe one intake runner is not atomizing fuel well....maybe carb itself has some issue with atomization, maybe a individual cylinder has some problem?
Any thoughts ya'll ??
I just rebuilt the carb (due to flooding problem) in late Jan. It is spotless, so these products have nothing to clean. These products alter the combustion characteristics of "straight" gas somewhat....IE easier to ignite, higher or lower flash point, octane is increased etc etc.
One or more of these is byproducts is helping out to create ideal ignition and eliminate the slight roughness.
I want to know why,exactly, these products improve the idle, and what problem they would point to.....IE maybe one intake runner is not atomizing fuel well....maybe carb itself has some issue with atomization, maybe a individual cylinder has some problem?
Any thoughts ya'll ??
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I'm guessing that the carb additive might act as an octane booster in your situation. It may indicate that you are running too lean at idle. Try re-adjusting your idle screws per procedure without the additive.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Most of those additives/cleaners have alcohol in them. This will effectively lean out your mixture. If your idle smooths out with that stuff in the tank, you are running too rich and the additives are helping you lean out. Check your float level, jetting specs and idle mixtures.
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