I've been running a edelbrock 600 on my chevy 400 for about 2 years now.
Runs pretty well, but it seems that I am always tinkering with the mixture screws and the idle screw.
I have basically found that when I turn up my idle, I can lean out my mixture, and vise versa.

But what is really correct and how do I really know when I have found the right combination?

The problem could be just me. I always think I am running to rich, so I am always trying to lean out the carb.
I always start out a 2.5 turns out on both mixtures, but in all my tinkering over time, I tend to turn them in till I only have 3/4 turn left and my idle is way up.

http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

There should be "best lean idle mixture" instructions in there.

I don't want to start a carb bash war here. But I got rid of my elb. carb because I got tired of trying to readjust it all the time. I swear that the more fuel that went through the carb, the less tunable it got. In the end, I don't think it mattered where I had it set at. It was always rich, and not very responsive. Maybe it was me or the carb. hell it's been several years ago. Now I avoid them. Good luck with your issues..Johnny

I had nothing but great results with eddy and carter afb carbs... Been running them straight for 7 or 8 years now..

Your adjusting the mixture wrong... That X number of turns is BS.

Set your timing 1st to what you need.. (most v8 chevys, 14 to 16* at idle, 34 to 36* total)

Now set your idle speed to what you want/like.. I put mine to right around 700 to 800 rpm

Now stick a vac gauge on a full manifold vac port (I use the little port on front driver's side of carb)

Turn one mixture screw in till engine just about dies, now turn it out as you watch the vac gauge.. Set the screw to where you get the highest vac reading..

Re adjust your idle speed (probbly have to turnit down a tad)

Then do the other mixture screw like you did the 1st one.. Turning it till you get the highest vac reading on your gauge.

Reset idle speed,

Now try to twitch the screws alittle more and see if you gain any vac.

Then turn them both back in enough to drop RPM by 50 rpm, if you don't have a low scale test tach then just turn them back in 1/8th of a turn.

Now they are set right... Not too rich and not too lean.. Just right.

This seems to be a common complaint for the Edelbrock Performer Carbs. I had one on a 327 in an old truck several years ago, and never could get things just right. Looking on several forums, I found that either the carb was perfect right out of the box, or it was out of adjustment and very few could ever get it right. I narrowed my problem to the choke (electric) which never seemed to come off completely. Driving, the carb was pretty responsive and got good mileage (at least as good as one can get with a 37 year old full size truck). I eventually gave up on it and now the carb sits on the shelf. Good luck with yours.

I'll pick up a vac gauge tonight.
Let you know tomorrow how it pans out.
Thanks Night Rider

I had nothing but great results with eddy and carter afb carbs... Been running them straight for 7 or 8 years now..

Your adjusting the mixture wrong... That X number of turns is BS.

Set your timing 1st to what you need.. (most v8 chevys, 14 to 16* at idle, 34 to 36* total)

Now set your idle speed to what you want/like.. I put mine to right around 700 to 800 rpm

Now stick a vac gauge on a full manifold vac port (I use the little port on front driver's side of carb)

Turn one mixture screw in till engine just about dies, now turn it out as you watch the vac gauge.. Set the screw to where you get the highest vac reading..

Re adjust your idle speed (probbly have to turnit down a tad)

Then do the other mixture screw like you did the 1st one.. Turning it till you get the highest vac reading on your gauge.

Reset idle speed,

Now try to twitch the screws alittle more and see if you gain any vac.

Then turn them both back in enough to drop RPM by 50 rpm, if you don't have a low scale test tach then just turn them back in 1/8th of a turn.

Now they are set right... Not too rich and not too lean.. Just right.
oh yea by the way thanks nightrider for all the imput that u gave me last year my ede runs awesome:cool:

I'll pick up a vac gauge tonight.
Let you know tomorrow how it pans out.
Thanks Night Rider


Your welcome...

THOMAS81Z... Your welcome man.. Glad you got it working right. The eddy carbs gets a bad rep cause people don't take the time to learn them and set em' up right.

I do wish edelbrock would set the float height and accel pump linkage up right from the factory.. That would fix 60% of the probs, it would also be nice if they threw in a cheap 2 port deadhead adjustable fuel reg.. That would solve another 30% of the probs. lol .

I have said it many times on here and I'll say it again for the new comers...

An engine does not know or care what brand name is stampped on the carb. All carbs needs dailing in ( adjusting to your engine).. If dailed in, you WILL NOT see much diff in power with X carb, vs. Y carb. All the carbs on the market will make with in 5 hp of each other if you take the time to dail them all into your engine.

As a gen comment from what I seen, box stock the eddy carbs are too rich for stockish engines and too lean for high performance engines.

Holleys out of the box are too rich for stockish engines and close for high performance mods.

But by changing the metering rods or just a simple step up spring change can have the edelbrock carbs just right for high performance use.

The 3 most common causes of probs with the eddy carbs are
1) floats set wrong, adjust to 7/16" at rest and 15/16" to 1" drop
2) accel pump linkage in the wrong hole, not giving enough pump shot.. Move it to the top hole.
3) too much fuel pressure.. These carbs only likes a mix of 5.5 psi.. and min of 5.0 psi.. Check with gauge, if above 5.5 psi then install an adjustable fuel pressure reg and set it to 5.25 psi.

Those 3 things is what causes the stalling under hard braking, and around curves, and bogging down when you punch it.

Then you get to the jetting, metering rods, step up springs, etc... Again all carbs needs to be set up for your engine.. 2 engines with the same specs could very well need 2 diff carb jetting/rod combos.. So you have to test it, try diff setups, read the plugs, look at the trap speed, etc to get the jetting right.

If you're turning the idle mixture screws in (leaner) and the idle speed is increasing then you're going the right direction. It's a back-and-forth game between the idle speed screw and the idle mixture screws.

Don't worry too much about how many turns out they are- you set them where the engine WANTS them to be set for best idle.

As you lean it out and the idle picks up you have to back the idle speed down to compensate. It will take several rounds through this to get it optimized. You will eventually get to the point where no matter what you do with the screws the idle gets worse. That's when it's optimized.

As was said above, you MUST have your ignition timing set properly first.

I'll add one more to the list- only set your idle on a fully warmed up engine, not when the choke is on and not even when it opens but the engine isn't yet at full operating temp.

This is, by the way, the same procedure you do on ANY carb. I helped my brother through this just last night on his "pocket bike" that uses a little Mikuni slide-carb. It wouldn't idle below 1700 without eventually just dying out. End result was that the carb wanted the idle mixture screw at 3/4 turn out, not the 1.5 turns it was set at from the factory. As he leaned it the idle got smoother and faster and he would slowly back the idle speed screw out to compensate. After 10 minutes of going back and forth between the idle speed screw and idle mixture screw the thing was running at it's factory specified 1200 RPM idle as smooth as glass and it would hold that idle rock solid for as long as you like.

Your welcome...


The 3 most common causes of probs with the eddy carbs are
1) floats set wrong, adjust to 7/16" at rest and 15/16" to 1" drop
2) accel pump linkage in the wrong hole, not giving enough pump shot.. Move it to the top hole.
3) too much fuel pressure.. These carbs only likes a mix of 5.5 psi.. and min of 5.0 psi.. Check with gauge, if above 5.5 psi then install an adjustable fuel pressure reg and set it to 5.25 psi.

Those 3 things is what causes the stalling under hard braking, and around curves, and bogging down when you punch it.

Then you get to the jetting, metering rods, step up springs, etc... Again all carbs needs to be set up for your engine.. 2 engines with the same specs could very well need 2 diff carb jetting/rod combos.. So you have to test it, try diff setups, read the plugs, look at the trap speed, etc to get the jetting right.

i had a few bogging on third gen cars i work on and i found the problem to be the fuel was boiling in the carb, worked fine till the car got warm and in warmer weather....but under decel left turns and acceleration it would stall or bog very bad....the accel pump well has to have the fuel level high to get the fuel into it but when the fuel was boiling it was causing low fuel levels in the bowl and it wasn't filling the accel pump well. i had very hot fingers finding that one.

I've found the main problem with Edelbrock Performer carbs is that the float height and drop is not set from the factory. Once the propper float height and drop is set, 99.9% of the problems go away.

It seems that finding a vac gauge with the little pump is a lot harder than I thought. Been to about 7 stores,(murray's, pep boys, autozone, harbor frieght, and a couple others.), and have not had much luck.
But I will get to it, and then dial this bad boy in.
I'll let you know as soon as I do.

Alright - so I found a vacuum gauge, and got right to work.
Set my idle for about 800~900, pulled my driverside vac plug, and attached the vac gauge.
Turned the screw till it dropped to about 15psi, and began to choke out, so I turned it back till I got to about 19psi.
Didn't need to re-adjust my idle.
Put my vac plug back into the vac line, and repeated on the pass side.
NO VACUUM!!!
Pulled the vac gauge, licked my finger and plugged the port. I could feel a little bit of suction, but just barely.
Put the vac gauge back on, and still had nothin.

Now, I will admit that I have often thought I had a problem with that side. Like when I turn the screw, it never made that much of a difference in the idle
I will also state that the car runs a little sparatic. For example, the vac gauge on the driver side jumped around alot(not sure what it is supposed to do, but it was not a constant pull). Bounced about 2 or 3 PSI.
Sometimes the idle will drop way down (500rpm), kinda sputter, and kick itself back up.

From rebuilding these carbs, I have noticed that the port goes directly into the butterfly area (little rectangular hole). Not sure where else it pulls from, but I don't think it is clogged.

Sorry about the novel, but I am not sure what to do next. Technically, it runs pretty smooth. Got a nice rumble goin on, but what do I do about no vacuum on the pass side. The vac gauge read absolutly nothin.
By the way, timing is good, engine was warm, idle was open (manual chokes work SO much better), and my gas PSI is about 5~5.5

Some ports on a carb are not full manifold vacuum. If you have vacuum on the right side, believe me, you have it on the left as well. Try revving the motor up some and I bet you find that port suddenly has vacuum (a ported vacuum source).

Leave the vac gauge on the drive side port... Do not move it to the pass side.

The pass side port is a timed port and will not have vac at idle.

Leave gauge on driver side port, and adjust both driver and pass side carb screws.

Exactly- what Night said.

HA! I'm an idiot!

Makes sense now that you guys mention it!
I'll take the vac gauge to work tomorrow, and try to tune is as soon as I roll in.

Wow - that was easy.
Runs pretty smooth! Pretty excited about the whole thing!
Runnin about 650 RPM, and the vac gauge shows about 20.5~21.

You guys should be sponsered by Edelbrock's tech group, cause those guys are absolutly useless - and they have an attitude!
Thanks for your help!

wait, so you're idling at 650 rpm - in park? I don't think my car would stay running at that rpm once i put it in gear... i guess i need to tune my eddy a bit too... this post is helpful.

I'm runnin a manual tranny, so I can turn the idle way down in neutral.
But my T/A however, I run about 650~700 in gear, and it shoots up to about 1200 in nuetral. (differnet post is discussing this currently!)

With an auto.. The RPM diff from park to drive is norm due to the torque converter being too tight and loading the engine.

I have mine set for about 650 rpm in gear, and in park it's about 675 rpm.. I have a 11" 2800 stall converter though so the converter is not loading up the engine