Tuning carb...
Thread Starter
Racer
Joined: Feb 2005
Posts: 373
Likes: 1
From: Bayonne NJ
Tuning carb...
I read the sticky about tuning your carb yourself. Has anyone used this method of tuning? By using a vacuum guage keep turning your mixture screws until you get the highest vacuum reading? My car is running way to rich right now.. you smell the gas on you after you shut the car off an get out of the car. Is this a safe way to tune??
Drifting
Joined: Jan 2006
Posts: 1,944
Likes: 22
From: Yooperville MI
Yes I've used a vacuum gauge for many years. If you are running rich there may be more to the problem than adjusting the idle, you may need to change jets and/or metering rods to get the ideal ratio.
Using the vacuum gauge is quite simple as long as you don't have a big cam which will produce low vacuum. A regular or mild engine should produce 16-18 inches of intake vacuum between 750 & 900 rpm. Connect the gauge to manifold vacuum and adjust the screws richer or leaner to obtain the highest reading. Once you get the highest reading turn both screws leaner until the rpm just starts to drop. Then turn the screws richer about a 1/4 turn. This should be the ideal setting.
Using the vacuum gauge is quite simple as long as you don't have a big cam which will produce low vacuum. A regular or mild engine should produce 16-18 inches of intake vacuum between 750 & 900 rpm. Connect the gauge to manifold vacuum and adjust the screws richer or leaner to obtain the highest reading. Once you get the highest reading turn both screws leaner until the rpm just starts to drop. Then turn the screws richer about a 1/4 turn. This should be the ideal setting.
Drifting
Joined: Oct 2004
Posts: 1,496
Likes: 1
From: Lafayette Louisiana
I use a vacuum gauge also. Mine was running rich at idle, so I used the wire in the idle circuit trick. This leaned it out and returned tunablilty with the idle mixture screws. I have a demon and I am not sure if this is applicable to the edl.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
i always use a vacuum gauge to set idle mixture also. simply adjust your idle mixture screw(s) to achieve the highest vacuum reading.
Make small adjustments at a time and let the motor stablize between adjustments before continuing. Make sure you are turning each adjustment screww about the same amount - when you are done both screws should be pretty evenly adjusted.
This is only for idle mixture though. If you are still running rich after setting idle mixture you need to look further just as your jet sizes, etc.
Make small adjustments at a time and let the motor stablize between adjustments before continuing. Make sure you are turning each adjustment screww about the same amount - when you are done both screws should be pretty evenly adjusted.
This is only for idle mixture though. If you are still running rich after setting idle mixture you need to look further just as your jet sizes, etc.
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
You say the needle bounces, does it move rapidly or slowly?
If rapidly, you could have valve problems, slowly would be a vacuum leak somewhere(went through this on my 327 before I replaced it with the 383)
If rapidly, you could have valve problems, slowly would be a vacuum leak somewhere(went through this on my 327 before I replaced it with the 383)
Pro
Joined: Mar 2004
Posts: 686
Likes: 0
From: Southeast
Originally Posted by BanGnGearS
Ok so the other morning i tried using the vacuum method.. Im running an aftermarket performer RPM cam and my vacuum bounces from 5-10. Is this normal with this type of cam?
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Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
as mentioned 5-10" vacuum is VERY low. Check carefully for a vacuum leak.
since you also mentioned the vacuum gauge was bouncing and not steady which it should be at idle, here is a helpful link that can help you diagnosis areas to look at based on the "type" of bounce or flucuation your vacuum gauge was giving you.
http://www.users.bigpond.com/ergoff/vac1.htm
since you also mentioned the vacuum gauge was bouncing and not steady which it should be at idle, here is a helpful link that can help you diagnosis areas to look at based on the "type" of bounce or flucuation your vacuum gauge was giving you.
http://www.users.bigpond.com/ergoff/vac1.htm