Lean spot from 1800 to 2,500 light throttle

[lorax]

Been down this road trying to get light throttle boggs out of carb.....buy a coouple of powervalves. One for 10.5 inches of vacuume and a 8.5 and give them a try. It only takes a couple of minutes to test. Leave the rest of the carb alone.

Does this recommendation apply when, as stated by the OP that the vacuum is usually around 16" during the period of the lean condition?

[n5ifi]

Been down this road trying to get light throttle boggs out of carb.....buy a coouple of powervalves. One for 10.5 inches of vacuume and a 8.5 and give them a try. It only takes a couple of minutes to test. Leave the rest of the carb alone.

Does this recommendation apply when, as stated by the OP that the vacuum is usually around 16" during the period of the lean condition?

I may be more knowledgeable about carbs than I thought.

[swatson454]

Personally, I'd run a vacuum gauge into the cab and see where it lands during the lean spot. Adjust PV accordingly.

[lluciano77]

This isn't a ficticious carb or a fictitious question. I haven't worked on my car in a few years. I don't have a lot of time now to be working on it either. Which is why I posted. To try and narrow down the trial and error. Sure I have an idea of what to go after first. But like I posted, all other tune is pretty much on the money. I also think it will come down to extending the idle circuit or bringing the mains in sooner.

[lorax]

Personally, I'd run a vacuum gauge into the cab and see where it lands during the lean spot. Adjust PV accordingly.

Are you suggesting you would change the PV to cover a lean spot between 18 and 2500 on a light to moderate accel, while pulling 16" of vacuum?

[lorax]

This isn't a ficticious carb or a fictitious question. I haven't worked on my car in a few years. I don't have a lot of time now to be working on it either. Which is why I posted. To try and narrow down the trial and error. Sure I have an idea of what to go after first. But like I posted, all other tune is pretty much on the money. I also think it will come down to extending the idle circuit or bringing the mains in sooner.

The over whelming majority says you can fix it with a PV change.
So how do you go about bringing in the main sooner aside from raising the float?

[swatson454]

Personally, I'd run a vacuum gauge into the cab and see where it lands during the lean spot. Adjust PV accordingly.

Are you suggesting you would change the PV to cover a lean spot between 18 and 2500 on a light to moderate accel, while pulling 16" of vacuum?

No. I'm saying that I'd find out what the manifold vacuum is doing at the problem area before I started haphazardly throwing PVs at it.

[lluciano77]

I work a lot and have failing health. To the people not interested in helping, yeah maybe I did get pissed off in the past and say something stupid. But not without getting a bunch of bs just like this to begin with. I will politely ask again for a helpful answer to the question. Any more nonsense on this thread, and i'll just walk away and figure it out my self with trial and error.

[lorax]

I work a lot and have failing health. To the people not interested in helping, yeah maybe I did get pissed off in the past and say something stupid. But not without getting a bunch of bs just like this to begin with. I will politely ask again for a helpful answer to the question. Any more nonsense on this thread, and i'll just walk away and figure it out my self with trial and error.

My last question was a legit question. If you have narrowed the possible fix down to bring in the main circuit sooner, how do you go about that other than raising the float level.

[swatson454]

I work a lot and have failing health. To the people not interested in helping, yeah maybe I did get pissed off in the past and say something stupid. But not without getting a bunch of bs just like this to begin with. I will politely ask again for a helpful answer to the question. Any more nonsense on this thread, and i'll just walk away and figure it out my self with trial and error.

My last question was a legit question. If you have narrowed the possible fix down to bring in the main circuit sooner, how do you go about that other than raising the float level.

I've had good luck in the past addressing this exact problem with Webers by reducing both the HSAB and LSAB and making sure there weren't any emulsion bleeds above the fuel level in the well.

I saw a difference of nearly a half point in AFR and a couple hundred rpm delay in main tip-in by simply going up one step in HSAB size or "air corrector jet" in Weber speak; which is opposite of what we're trying to accomplish here. I know you can only reduce the air bleeds so far before it starts pulling too rich on the top end but it did help bring the boosters in sooner, at least in my case. I think it has alot to do with the pressure difference between the float bowl and the emulsion well as to how soon the fuel begins to lift and the emulsion bleeds become active.

I don't know how much of this carries over to a Holley but it may still be worth looking into. This wasn't an I/R manifold either. Common-plenum deal.

I know I've opened myself up to a flogging but my flame suit is on

[lorax]

Some thing I noticed in the original post that caught my attention right off but left it there, was the "Holley 4 hole spec" with BG blocks. I am not familiar with BG's blocks, but I know that the holes in some QF blocks do not line at in the same height as they are in a Holley, in reference to the float level.
Just a thought.

[steve cowan]

i am glad lorax and gary c are friends again,you guys nearly blew me out of my boots while i was reading this post

[jmarkaudio]

Raising the float might help, if it's low. .028 is a bit small, try going up to .030 and fine tune with the idle bleeds. Also, lean readings at light throttle/low loads are not an issue as long as you have no stumble or surge. The more efficient the engine is the leaner it will tolerate.

Still sticking with this. Is it just a lean reading or is there something wrong with the function?

[vincenelson]

My answer about will a 10 or 12 inch vaccume powervalve work with 16" of vaccume? YES Well I am sure that when the throttle is depressed the vacuume will drop......the statment was when at cruze he had 16 " of vaccume. Again I chased the same problem for a full day and tried a bunch of things in the process like increasing the idle transfer circuit, timing, riching idle circuit. In my case changing the powervalve made the car fun to drive.....no slow rolling throttle bogs, nice responce, all in hi-gear at about 30 mph

[zums]

im also stickin with my orig post, been down that road on a similar tune more than once