[killerformula]

I just recently put a holley carb on my car (4160, part number 3310S). The car starts much better than it did in the past, but its very aparent that the carb is running AWEFULLY rich. So much so that you can see it from time to time in the exhaust, and it will leave a gas cloud when you rap it up. When I unplug a vacuum line (thus giving it a vacuum leak) the idle iproves significantly, leading me to believe its starving for air (car idles pretty choppy).

My question is this: I've done my share of research and know that while the car is idling, its only able to get fuel from the "idle circuit." This is tuned, as far as I know, by the idle mixture screws, but when I bring them in to lean the mixture, the idle suffers. George (1BAD) told me to back the primaries down about 3 sizes. I'm confused, I thought the idle circuit didn't involve the primaries? Can somebody elaborate?

K

 

[Lonestar]

If your butterflies are open too far, the engine will start drawing from the main metering system. When you turn in your idle screws all the way, does the engine die?

Also, check your float levels.

A blown power valve (or wrong size) could cause this also.

http://www.bob2000.com/carb.htm

 

[killerformula]

hmm well the carb is brand new and has blowout protection on it. The cam is a 280 comps and has plenty of vacuum (maybe not like stock, but more than freaking 6.5 inches!). What do you mean by "butterflies?" I thought idle was controlled soley by the idle mixture circuit. Maybe the idle is high enough to influence the transfer circuit as well?

K

 

[1BAD80]

Why buy a book when you can get it for free.
http://www.holley.com/HiOctn/TechServ/TechInfo/FMCTech.html

Eric you have to Stop the beer drinking before working on engine, just a reminder. :drunk:
If you ever want to get it fixed as offered many times, come on up instead of complaining. imp: :welcome:

 

[lluciano77]

Set the idle so that the transition slots on the primaries look like square holes from the bottom of throttle plate. Then, use the secondary throttle screw to raise or lower the idle.

Make sure your vacuum in gear is below the range of the powervalve. You said you have 6.5 inches at vacuum. If that is the case under normal conditions I wouldn't run more than a 3.5 powervalve. I think this is the most likely problem.

Don't jet down three sizes. Run the stock jet sizes. You will need to fix your current problem before getting the jets right.

 

[killerformula]

yeah it might be a bit... you kno... after I just got hit up for the towing charge and all.

1BAD you've saved my butt a bunch of time man, thanks again. BTW, I just noticed the individual systems blow up pictures on that site...

K:drunk:

 

[jameskirk1]

I've found an easier way to reset the butterflies on my Demon when I get it out of whack, and it doesn't require removing the carburetor...(same as a holley)

If the butterflies are showing too much transfer slot, you will be able to shut the idle screws totally and the engine will not die...

When it gets out of adjustment like that what I do is screw the idle screws in all the way, and while the engine chugs along and struggles, I slowy back off the idle speed until the engine dies...Then back the idle adjustment screws out a turn each and re-fire the engine...You should regain all idle mixture adjustment at that point...:thumbup:

Also remember that a retarded initial advance will cause a sluggish, rich smelling idle...

 

[Lonestar]

hmm well the carb is brand new and has blowout protection on it. The cam is a 280 comps and has plenty of vacuum (maybe not like stock, but more than freaking 6.5 inches!). What do you mean by "butterflies?" I thought idle was controlled soley by the idle mixture circuit. Maybe the idle is high enough to influence the transfer circuit as well?

K

The butterflies are the four round discs on the bottom of the carb that flip open when you hit the throttle.

There is a little slot on the side of each butterfly (transition slot) that if uncovered too far will cause the engine vacuum to start drawing fuel from the primary circuit instead of the idle circuit. If you have this problem then turning the idle mixture screws all the way in will not cause the engine to die.

Read the website I provided a link to, it explains a lot.

 

[killerformula]

ah ok. I was thinking of them as throttle plates. Anyway, yeah, I'm new to the holley thing. And what you're saying makes sense, there are only three sources of fuel, and two are erronious: idle circuit, transfer circuit and power valve. I would really hope the powervalve is fine considering its only got less than a dozen starts on it. I'll check the transfer circuit tomorrow.

K

 

[lluciano77]

The powervalve is fine.

 

[killerformula]

it doesn't tend to start very well when the initial is tuned for max vacuum. It hits the wall at high R's too with more initial advance. When I tune the idle mixture I'll tune the initial for max vacuum, then drop it in gear and set the idle. From there I'll set the idle mixture for max vac. Or maybe I shouldn't, maybe I should leave the timing where I drive it, then tune the idle mixture from there? ANyway, if I can get them all the way in, the transfer circuit is working overtime and I have butterflies open, correct?

K

 

[lluciano77]

Never tune your ignition curve based on what makes the most vacuum.

More advance will raise your idle.

You should still be able to idle down within a reasonable performance advance curve.

The way you curve your distributor is to make a bunch of runs. Some at speeds between 2,000 to 3,500 RPMs where the low speed detonation happens, and some at WOT.

Every time you add more initial, you have to subtract mechanical advance to get your total.

Start out with 34o to 36o total. Keep adding 2o more initial (subtracting mechanical respectively) until you either hear detonation between 2,000 and 3,500 RPMs, or the starter kicks back on start up. If either happens back off at least 2o and call it good. I think you would be safe to start at 16o initial.

Once you get your initial right you can play with the total. I wouldn't go over 38o total. If you hear detonation at WOT, back off 2o to 4o. My car likes 32o to 34o total. Total isn't as important as initial in a street driven car.

Now all of this is assuming that you know what detonation sounds like. You better make sure before you try this that you do know what to listen for. If feel a power loss as you add advance, but don't hear anything, back off 2o.

 

[western star]

1Bad80 thank you for that link on Holley carbs. I just installed a new Holley 670 Street Avenger with an electric choke and the fast idle doesn't come on at all. According to Holley the factory sets this at around 1500 rpm. I have nothing but an idle. The carbs works great. The choke comes on and goes off when it suppose to just no fast idle. You're suppose to use a 1/4 " wrench to adjust the fast idle speed but I can't even see the screw under the fast idle cam. Is there an easier way to get at this adjustment? Never done a fast idle before.:drunk:

 

[1BAD80]

You can use a screwdriver, its on the left side on the main linkage closest to the carb in the bottom middle.
You can see it from the rear drivers side (left side).
Adjust it after its fully warm.
Hollys site has the specs on how to set the carb up during/after a rebuild that is good to use for tuning in the choke linkages and such.
LOL

Killerforumla: you should only adjust one thing at a time so you know what the changes are. You are changing to many things at one time, without keeping any record on any tuning thats been done or changed, so you can put things back to basic.
Reading this posting after talking to you is two different scenario's for one problem.
Rapping it up from idle and getting smoke don't tell to much of what is happening for a root cause analysis to fix the problem, plus lack of mileage for the rebuild for a WOT clean out of the carbon form the other carb or this one and check how it performs since you never hit WOT yet.
Your problem is off idle from what you told me.
lluciano77 said the same thing on timing as I stated to you.
Stop jumping around and fix one thing at a time and the motor will get tuned in correctly. You bought a vacuum gauge and did not even use it yet.
Lets get it together before asking more questions. :spank:
Rapping it up and the bog when hitting it is the acc. pump giving to much gas as we talked about before, and a rich carb will make it worse. :sweat: imp: :evil:

 

[western star]

1Bad80 thank you for that.

 

[killerformula]

You can use a screwdriver, its on the left side on the main linkage closest to the carb in the bottom middle.
You can see it from the rear drivers side (left side).
Adjust it after its fully warm.
Hollys site has the specs on how to set the carb up during/after a rebuild that is good to use for tuning in the choke linkages and such.
LOL

Killerforumla: you should only adjust one thing at a time so you know what the changes are. You are changing to many things at one time, without keeping any record on any tuning thats been done or changed, so you can put things back to basic.
Reading this posting after talking to you is two different scenario's for one problem.
Rapping it up from idle and getting smoke don't tell to much of what is happening for a root cause analysis to fix the problem, plus lack of mileage for the rebuild for a WOT clean out of the carbon form the other carb or this one and check how it performs since you never hit WOT yet.
Your problem is off idle from what you told me.
lluciano77 said the same thing on timing as I stated to you.
Stop jumping around and fix one thing at a time and the motor will get tuned in correctly. You bought a vacuum gauge and did not even use it yet.
Lets get it together before asking more questions. :spank:
Rapping it up and the bog when hitting it is the acc. pump giving to much gas as we talked about before, and a rich carb will make it worse. :sweat: imp: :evil:

I've hit WOT, like I said, it bogs and then moves in. If I stab the car to about half throttle it bogs and then picks up. You're right that's a different issue. But I called you that one night just to tell you how fast it went, remember?

I haven't adjusted anything yet.

My issue I'm talking about now is why is my car so rich at idle, its damned near drowning and I have to feather it just to smell the rich idle. This is problem #1. After I solve problem #1, I can move on to #2 which is bogging through WOT and through half throttle (accelerator pump cam like we discussed). Just trying to talk through it George, not trying to undermine your advice. Again, you've saved my butt a million times, I'm just new to this and talking through it helps me think!

Rock on wit yo bad self george-

K:thumbup:

 

[NAIRB]

Lower your float level while it's running. I'll betcha it smooths out dramatically.

 

[rifraf]

Say,not to complicate things,but because of a lot of wasted time and frustration,I know I have started to lube my distributer weights prior to any carb tweaking,just to insure everything stays constant,just something to consider if you want to get it just so."

 

[1BAD80]

DO NOT USE LUBE INSIDE THE DISTRIBUTOR.
Just wipe them down with a oil rag then wipe dry. Grease will get thrown around and loose spark and collect dirt.
Make sure on the stamped side of the weights are flat. I use a oil stone and get the burrs off, this is where they like to stick.
Only a tiny amount on the bushings inside.
LOL

Eric have you done everything as discussed and mentioned in setup of the carb ?
Meet me 1/2 way tomorrow and I'll tune it for you, I have everything needed and should take about 1/2 hour.
Give to me a call if you want it fixed.
G

 

[killerformula]

I'd love to come meet man, but my girl is in from georgia and we're having dinner with her folks tomorrow! Hmmm, are you available an evening of this week? I could jump right in my car after work at 5pm and be to your place by 6 or so...

I checked the float while it was running through the site hole, no gas came out so I assume its set correctly...

K