Edelbrock Adjustments
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New User
Joined: Nov 2003
Posts: 23
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From: Maine
Edelbrock Adjustments
I have played around with trying to get my 390 to idle a little better, had a buddy of mine look at it and he screwed around with the adjustment screws on the front of the carb, now i dont know where to put them back to, any help would be appreciated. its an edelbrock 750 cfm, if that helps any. I bottomed the screws out and then played with them until it sounded pretty good but i want to make sure that the settings are right.
Thanks Swampy
Postmaster
Joined: Jul 2003
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From: iowa
hey i have a 600 edelbrock and 1.5 is good but 2 turns and if i stomp on the pedal at a stop the truck likes dies but if you ease into to pedal while smashing it to the floor, if such a thing, its fine.
Postmaster
Joined: Jul 2003
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From: iowa
i have been told that both are mixture screws that only affect low speeds. So if you are running lean on top end it doesn't seem that you can adjust. I was under the impression that the screw was for that side and the other screw for its side.
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Elder User
Joined: Dec 2003
Posts: 534
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From: Hoquiam, WA
I was under the impression that one was for the primaries, and the other was for the secondaries. But I could never get a straight answer on the Edelbrock carbs. Especially why the diagram showed the port and timed vacuums opposite of what the actually where on the carb. I bought one when they first started coming out, maybe things have changed. But the best adjustment I ever made to one of their carbs, was going back to a Holley.
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Fleet Mechanic
Joined: Aug 2003
Posts: 1,546
Likes: 46
From: Kemmerer, Wyoming
fordeverpower is right... the screws are for the low-speed circuit in each of the primary "barrels" of the carb... they only effect your idle and off-idle mixture. Adjusting mid range and wide-open throttle requires changing the jets along with other mods.
Here's the best way I've found to tune the idle mixture on any carburetor:
1. Start at 1 1/2 turns out if this is a new install.
2. Work with one screw at a time.
3. Turn it in until the engine just starts to slow down, then back it off a little bit. NOTE: Your final turn should always be IN on a spring loaded needle, so back off a little more, then turn it slightly in.
4. Repeat the procedure on both screws 2-3 times, as final adjustments will be needed.
This will basically set your idle to run as smooth as possible with the leanest mixture possible, which is the desired effect if all other parts of the engine equation are functioning correctly.
Also try to keep the idle speed close to specs while doing this.
This technique has worked for me on several carbs, from the 1 bbl on an I-6 to a Holley 4 bbl 1250 double-pumper.
Here's the best way I've found to tune the idle mixture on any carburetor:
1. Start at 1 1/2 turns out if this is a new install.
2. Work with one screw at a time.
3. Turn it in until the engine just starts to slow down, then back it off a little bit. NOTE: Your final turn should always be IN on a spring loaded needle, so back off a little more, then turn it slightly in.
4. Repeat the procedure on both screws 2-3 times, as final adjustments will be needed.
This will basically set your idle to run as smooth as possible with the leanest mixture possible, which is the desired effect if all other parts of the engine equation are functioning correctly.
Also try to keep the idle speed close to specs while doing this.
This technique has worked for me on several carbs, from the 1 bbl on an I-6 to a Holley 4 bbl 1250 double-pumper.
Lead Driver
Joined: Sep 2003
Posts: 5,844
Likes: 6
From: Albuquerque
Originally posted by ACESN8S
I was under the impression that one was for the primaries, and the other was for the secondaries. But I could never get a straight answer on the Edelbrock carbs. Especially why the diagram showed the port and timed vacuums opposite of what the actually where on the carb. I bought one when they first started coming out, maybe things have changed. But the best adjustment I ever made to one of their carbs, was going back to a Holley.
I was under the impression that one was for the primaries, and the other was for the secondaries. But I could never get a straight answer on the Edelbrock carbs. Especially why the diagram showed the port and timed vacuums opposite of what the actually where on the carb. I bought one when they first started coming out, maybe things have changed. But the best adjustment I ever made to one of their carbs, was going back to a Holley.
I thought to adjust the secondaries go with the spring loaded screws in the back of the carb. Is that right?
The cool thing about Edelbrock carbs...that re-jetting is so simple and does not require removing the carb. Also, once I installed the off-road or 4x4 needles...the carb has worked flawlessly. I had a holley "once"...but just wasn't for me or my FE. To much adjusting.
Elder User
Joined: Dec 2003
Posts: 534
Likes: 0
From: Hoquiam, WA
I gave up on them, I even had a friend who built up Carters tear into it, still no luck.
But after reading the other post, https://www.ford-trucks.com/forums/s...hreadid=188228 , and thinking back, most of the problems I had were with the "blended fuels" they used where I used to live. The fuel service that I had used actually got nailed for using more than a 10% mix of ethanol. But by that time I had already switched back to a Holley and wasn't having any problems.
But after reading the other post, https://www.ford-trucks.com/forums/s...hreadid=188228 , and thinking back, most of the problems I had were with the "blended fuels" they used where I used to live. The fuel service that I had used actually got nailed for using more than a 10% mix of ethanol. But by that time I had already switched back to a Holley and wasn't having any problems.
