Holley 750 dp, way rich at idle.

[falkenracing]

Ok, here we go, time to start buging people with some rookie questions in the fuel-blending department. Bear with me please.
I have on my warmed over 383 (stealth heads, headers, cam, msd dist, etc) a Holley 0-82751 carb, wich makes the car smell of unburnet gas at idle/light load/low speed driving. I have not tutched it much since I've hade other problems since start up last summer, but now it's about time to start. Wide-band O2 sensor is going in soon, but to start out I would like to have the idle mixture leaned out for everybodys pleasure and well beeing.

What I have done so far is: played with idle mixture screws (best vac. of 15"hg at 3/4 turns out) and i have tried to lean the IFR with a 0,23mm wire (yes, I do it metric, if thats a problem I will have to convert for you). The stock IFR was about 0,73mm. Can't say it did much, but common sense tells me that if the wide-band was in it would show some difference, smaller hole, les gas.
Would trying to fiddle withe the air-bleeds be of any help you reccon? I would like to get the idle mixture leaner quiite soon, even if I later will ahve to go back and change stuff when I start tuning in the rest of the carb.

[falkenracing]

Also, base timing at this state is set at 15*, 36* total, will be seting it as to the article here in the tech-section and try reducing mech.advance acordingly. (pro billet, no vac.)

[cudabob496]

well, if smell unburnt gas, with car idling, check for gasoline leaks around the carb, or fuel system in general.
If carb is old, may need a rebuild kit.  What are your jet sizes?

[brads70]

What is your vacuum in gear at idle? You power valve needs to be 2 points lower than that. Eg if you have 6inches of vacuum you need a 4 power valve. If it has backfired you may have blown the power valve also? 

[Strawdawg]

and, if Brad's suggestion does not help, then you may have to lean the idle circuits down with a very fine piece of wire in each one...

Double pumpers are usually set up pretty rich from the factory because they were intended for cars with larger duration cams that idle faster and need more fuel to run....

[Chryco Psycho]

wire in the bleeds will richen the mix the smaller the holes at the top the responsive the vacuum is at the bottom , opening the bleeds will lean it though , the outer bleeds are the idle ones , inner are the jet bleeds .
 you may want to make sure you have the correct gaskets inside the carb float level set to high can cause it to run rich also

[Strawdawg]

wire in the bleeds will richen the mix the smaller the holes at the top the responsive the vacuum is at the bottom , opening the bleeds will lean it though , the outer bleeds are the idle ones , inner are the jet bleeds .
 you may want to make sure you have the correct gaskets inside the carb float level set to high can cause it to run rich also

I did not say "in the bleeds"    I should have specified in the metering blocks-the idle circuits

[Chryco Psycho]

Duh OK 

[Strawdawg]

Duh OK 

But that brings up a question

The new carbs are so much nicer because we can change the feeds, etc...but the parts seem high to me-particularly when you may not know exactly what you will end up needing.  Have you seen any kits with a variety of sizes of jets and bleeds like we used to get for various carbs?

The above is why I like FI so much

[Chryco Psycho]

there are bleed kits with a range of common sizes for both jetting & idle bleeds but if I recall right they are about $300 ..... ouch
 I went the other way & bought a numbered drill set & bought blank bleeds for approx. $2 each & then I would start on the smaller side so I could enlarge if it was not enough change , , I always kept ones I drilled but did not use .

[Strawdawg]

yeah...I use wire drills...but cautiously

First thing I do is to check about three times that everything is set up properly before I change anything.  Maybe that comes from fixing things that were not really broken?

[brads70]

there are bleed kits with a range of common sizes for both jetting & idle bleeds but if I recall right they are about $300 ..... ouch
 I went the other way & bought a numbered drill set & bought blank bleeds for approx. $2 each & then I would start on the smaller side so I could enlarge if it was not enough change , , I always kept ones I drilled but did not use .

   That's what I did too, bought a pack of the smallest size then drilled them out as needed.

[cudabob496]

stick sight glasses on float level view ports

[falkenracing]

Ok, I'll start answering some questions:

No gas leaks as i can detect, and the smell seems to be coming from the tailpipes. And the exhaust analyser (4 gas tester at work) is with me on that one.

Idle vaccum in gear: well, I have a stick shift, so 15"hg that would be.

Have, as stated, put peices of wire in the IFR on both metering blocks.

I have checked and re-checked floatlevel time and time again, and it is right at the bottom of the sightplug, not dribbeling fuel out at idle.
The carb is about three years old, and used on this car and the one before that, and the same problem with that as well.

[Strawdawg]

try the next size up wire that you can find   As I said, dp's are often pretty rich-particularly on the idle circuit.  With that much vacuum, I would think it would idle pretty well around 13 or 13.5-1.

Or, open the air bleeds as Chryco suggests with the next size up wire drill-that might be more logical at this point

Carbs are a bit hard at times to get to idle well much leaner due to variations in distribution between cylinders

Sounds like you have had it apart so it has new gaskets in it.  I had one long ago that did not act quite right and a straight edged said the mating surfaces were not truly plane so the gaskets were sealing less than perfectly...