Edelbrock carburetor running rich - Vintage Mustang Forums
Vintage Mustang Forum
HomeForumGalleryClassifiedsAbout UsAdvertiseContact Us
» Auto Insurance
» Featured Product
Go Back   Vintage Mustang Forums > General Discussion > Mod and Custom Forum
Vintage-Mustang.com is the premier Ford Mustang Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools
Old 06-04-2010, 10:06 PM   #1 (permalink)
Senior Member
 
Scottem's Avatar
 
Join Date: Jul 2007
Posts: 160
Default Edelbrock carburetor running rich

Part # 1803 500cfm 4bbl

Symptom: Exhaust stings my eyes and really stinks badly.

I assume the carb is running rich and after adjusting the air/fuel screws on the front of the carb, confirming there are not gasket leaks, timing is good as is the vac gauge reading (18lbs). Adjusted the auto choke and its good. Condition persists..

Edelbrock says the primary jets on this carb (primary carb on a dual carb set up) are

Metering Jets: .086
Metering rods: .065 x 0.57

I have a tuning kit from Edelbrock.

Question: What size jet and rods should I run to make the rich condition go away?
__________________
Scotty
67 fastback
68 coupe
03 SVT Cobra
Scottem is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 06-04-2010, 11:31 PM   #2 (permalink)
Senior Member
 
wilit's Avatar
 
Join Date: Apr 2009
Posts: 919
Default

Every time I've read a thread like this, some guy always posts up, "What's your fuel pressure set at?" Apparently Edelbrocks are very sensitive to fuel pressure and should be set at 4.5 psi. Mechanical pumps can produce more than 4.5 psi, so it's a good idea to check it.

I have a similar issue with my Edelbrock, but I haven't taken the time to install my pressure regulator yet.
wilit is offline   Reply With Quote Quick reply to this message
Old 06-04-2010, 11:46 PM   #3 (permalink)
Senior Member
 
Scottem's Avatar
 
Join Date: Jul 2007
Posts: 160
Default

Running dual carbs the 6psi its currently at quickly lowers to less than 2psi til I pull a Dukes of Hazzard and turn on the electric pump.

Suppose its ok to go two steps leaner? The exhaust really stinks..
__________________
Scotty
67 fastback
68 coupe
03 SVT Cobra
Scottem is offline   Reply With Quote Quick reply to this message
Old 06-04-2010, 11:53 PM   #4 (permalink)
Senior Member
 
wilit's Avatar
 
Join Date: Apr 2009
Posts: 919
Default

I don't think the jets and rods have any effect on A/F ratio at idle. That's the job of the idle screws and idle circuit. The rods and jets only come into play once the throttle is cracked (at least that's my understanding of Edelbrock carbs).
wilit is offline   Reply With Quote Quick reply to this message
Old 06-05-2010, 01:16 AM   #5 (permalink)
Senior Member
 
Scottem's Avatar
 
Join Date: Jul 2007
Posts: 160
Default

A little background about the car.. Last summer a couple following me in their ragtop Saleen said they had to back off because my exhaust was making them sick and it stank something fierce. At a rest stop I asked some of my buddies to smell the exhaust as I worked the gas pedal a little. They had the same remarks, no doubt I had a rich condition. Dual carbs really are not worth the trouble.

Found a few issues tonight.

The fuel regulator doesn't work. The 6psi couldn't be adjusted (using a stock fuel pump) so the regulator will have to be replaced.

An attachment to the throttle on the primary carb wasn't allowing the throttle to return all the way. The throttle was cracked part way open (about 200-300 rpm worth). I suppose that means the car wasn't idling correctly? That in mind, I did the easiest thing and go "one step" down which Edelbrock says to install a different set of metering jets down to .067/ .055 After working the throttle a little bit (at 180 degree engine temp) it helped a little. The difference was noticeable but still stank remains.

I'll replace the fuel regulator and if the rich condition persists, then I'll goto a second step (replacing the primary jets and metering jets). Found two air/fuel screws were out of adjustment. That added 2.5 lbs of vac so i adjusted my timing which further lowered the idle speed.

At least I was able to reduce the idle speed from 1200 to 900rpm.
__________________
Scotty
67 fastback
68 coupe
03 SVT Cobra
Scottem is offline   Reply With Quote Quick reply to this message
Old 06-05-2010, 08:14 AM   #6 (permalink)
Senior Member
 
kenash's Avatar
 
Join Date: Dec 2006
Location: Severna Park, MD
Posts: 3,248
Default

Quote:
Originally Posted by Scottem View Post
Part # 1803 500cfm 4bbl

Symptom: Exhaust stings my eyes and really stinks badly.

I assume the carb is running rich and after adjusting the air/fuel screws on the front of the carb, confirming there are not gasket leaks, timing is good as is the vac gauge reading (18lbs). Adjusted the auto choke and its good. Condition persists..

Edelbrock says the primary jets on this carb (primary carb on a dual carb set up) are

Metering Jets: .086
Metering rods: .065 x 0.57

I have a tuning kit from Edelbrock.

Question: What size jet and rods should I run to make the rich condition go away?
You want to go leaner! That's the quick answer. Sounds a little "smart a...", I know, but this retort is as broad an answer as your question.

Having extensively tuned a 1405 (specifically), both on the road and chassis dyno,
I start out tuning carbs with:

1. attach a vac gauge, (manifold vac) to insure no leaks most street engines will be between 15-20 hg

2. insure your timing is within parameters most rigs run 12-14 deg.

3. attach a vac gauge ( manifold vac) with your idle at or near 750-900 (?) adjust each mix screw for the highest vac reading, all the while maintaining your desired idle setting.

4. Also, know there are two vac ports on that carb, OK 3, if you count the PCV port. One is full manifold and the other is timed" or "ported". As every engine is different, the choosing of which will depend on how your engine responds to the input. This is a whole other can of worms.

If you bought this carb new, you would have gotten a setup/install guide. In the back of the guide is a graph chart for tuning the carb's AFR. To go lean you select "X" metering rods and springs, to go richer, you selct these etc. If you don't have a guide, it is available on their site as a download in the technical section.

"No one" on this site can recommend specific rods and jets. I will go out on a limb and state that one would usually start by changing the metering rods. It's a case of knowing where the AFR goes "fat" (rich).
Each engine is different in too many ways for any of us to answer " What size jet and rods should I run to make the rich condition go away" again, the simple answer to your quest may be "go leaner".
Outside of many hours of road testing, a chassis dyno is your next best way to learn what your AFR is doing over a broad RPM range. Otherwise, buy an AFR meter on your own and have at it.
Good Luck!
__________________
Ken ..
64 1/2 Poppy Red too!, Cvt. Resto-Mod
333 Cu.in. T5z, 3:55, Dual 40 mm DCOE Webers
Performer RPM, CI cam, TFS/TWs, Tri-Ys, Discs w/Shelby Drums
Severna Park, MD
kenash is offline   Reply With Quote Quick reply to this message
Old 06-05-2010, 02:01 PM   #7 (permalink)
Senior Member
 
Scottem's Avatar
 
Join Date: Jul 2007
Posts: 160
Default

Great post! I am going leaner as outlined in the Edelbrock owners manual. Did one step leaner last night (just metering rods) and it helped so I'm going to a step two tonight (rods and jets).
I have a vac gauge installed on the car so I use that to set the mixture screws.
__________________
Scotty
67 fastback
68 coupe
03 SVT Cobra
Scottem is offline   Reply With Quote Quick reply to this message
Old 06-05-2010, 02:59 PM   #8 (permalink)
Senior Member
 
kenash's Avatar
 
Join Date: Dec 2006
Location: Severna Park, MD
Posts: 3,248
Default

"Scotty",

Now, you're are on the right road. Don't forget to document every adjustment you make. Start with the base line info, then add to it.
PlaySafe!
__________________
Ken ..
64 1/2 Poppy Red too!, Cvt. Resto-Mod
333 Cu.in. T5z, 3:55, Dual 40 mm DCOE Webers
Performer RPM, CI cam, TFS/TWs, Tri-Ys, Discs w/Shelby Drums
Severna Park, MD
kenash is offline   Reply With Quote Quick reply to this message
Old 06-05-2010, 04:32 PM   #9 (permalink)
Senior Member
 
Scottem's Avatar
 
Join Date: Jul 2007
Posts: 160
Default

Thanks much !
__________________
Scotty
67 fastback
68 coupe
03 SVT Cobra
Scottem is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Vintage Mustang Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 10:07 AM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.3.2 ©2009, Crawlability, Inc.