Im working with a 1000cfm holley (4150). Its on a 540 (9.6:1)solid roller 680/685- 255/264 110lsa. The carbs jetting is 88/98 and the main air bleeds were .028s, the carb always seems to be running lean, so I switched from 3.5 pv to a 6.5 and switched the air bleeds to .026, It seems to be pulling more fuel now, does the reduction in the main air bleeds orifice make a significant differece in how it pulls fuel? I went to the air bleeds because the more main jet that I throw at this thing dosent seem to have a change. Do these size main jets seem excessive?

Thanks Rich

How good is your fuel system?
Cam seems big for that comp ratio.

seems like ALOT of jetting to me, for the power that it's making.

Guys, its a 540 AND its a 1000 cfm carb. 84s, I beleive are "stock" in that carb, so you're not way off. ASSUMING the 98s are with no power valve back there, you're not excessive, just BIG.

Sure the fuel system is delivering the goods? This is 1/2" line stuff with a competition type pump.

Not too familiar with the 1000 Holley but just for comparision...
My 995 King Demon specs:
Air bleeds;
Idle .046
Inter .070
HS .035

Jetting is 85 square, NO PVs
Squirters are 42 with annular boosters.

Same cubes, almost another point in CR, similar cam specs. Running a Super Victor intake w/box stock 325cc Darts.
Good MPH...ran 99+ last weekend @7.0x...3700 lb car.

Annulars defintely use less jet, is the Holley 1000 annular?

The fuel system is all 8an / mallory 140 return style. Its definately not running out of fuel. The cam profile is really not that big, its amazing how much the cubes eat up the cam profile, this thing idles nice at 850rpm and makes 11 inches. The powervalve is plugged on the secondary side.Its just this carb seems to have elevated my exhaust gas temps compared to the 870cfm carb I have. And cruise A/F is 14 to 15. dont understand what it takes to get this thing to pull fuel. Perhaps the larger venturis cut down the signal.

hey just for your info,,my 540 solid roller street engine runs a demon 1090, my comp ratio is 10.3 to 1, cam 651 lift duration 254/262 at 50. i run 91/94's on the street and 94/99 at the tract,its 3900lbs with me in it,NO hesitation and ran 6:88 at 101mph in the 1/8th, H.P. on this is 690 at the crank,and 656lbs of torque

I am assuming it's on a std 4150 base. How do they get that much airflow through a design that really is not efficent at 850 CFM let alone 1000. Yes the bleeds make that much difference but put the power valve back in it should help.

badss540,

I think Im right around the power level that your running, perhaps Im not that far off, maybe I will try the PV in the back.

Mike - I might be off but I believe the baseplate measures 1.75 and with a throttlebody measuring approx 1.375 which is from an 850 it will flow 950cfm. The throttle bores in mine have to be close to 1.75 along with the baseplate its 1000cfm at least this is what im told. I am far from an authority on carbs, its amazing to me that .002" can cause this thing to pull that much more fuel.

What is the condition of your plugs?
High EGT can also be a rich condition.
How much ignition timing are you running?

after a 10mile cruise the ring of the plug looks brownish black along with the porclean the top of the electrode is clean metal color. But before I made the air bleed/PV change I couldnt get any color on the plugs. This is mostly cruise and idle. Its nearly impossible for me to do full power runs and shut down to look at plugs. I think I need to set up my LM1 and recheck it again.
The timing is at 38 deg all in by 3000, does this sound to high? I run a digital 6 with there coil wires and msd billit dist.

Does anyone know of a rear wheel dyno facility in the north jersey area. I bet this would save alot of time.

Thanks Rich

I didn't catch if you mentioned what type of boosters the carb has.

I have a 13:1 510 cubic inch big block with .660 lift 256/264 at .050 cam with 108 lobe sep degred in at 104 intake centerline. Ported canfield rec port cylinder heads with a eldebrock victor with a 1 1/4 carb spacer/adaptor for a demon 850 double pumper.
I'm running 84s in the primary and it came with
85s in the primary and still seems rich, however;
my altitude is 6100 feet.

dog leg boosters

Downleg boosters have the lowest vacuum signal amplification of all. Combine that with the big venturies and the signal is quite low. This probably explains why the air bleed change made such a difference. You may have to work with them to get the mixture right.

One other thing make sure you are getting enough air to the carb. I have come across that problem when making jet changes seemed to have no effect.

First of all I am not an expert in this. However your numbers sound similar to mine. In working with my lm1, I have found that taking out the front power valve and going up in jet size will help bring the 14-15 to 1 down. It will also make the overall fuel curve that you see on the print out flatter. (not as many spikes when driving around) With that said, I have yet to find any advantage (in my set up) to removing the power valves. I thought so at first but have now changed my opinion. In fact it seems to launch harder with the power valves in. With the power valves in, loaded on the converter, I'm about 12.8 to 1. With out the power valves its closer to 12.0 to 1. The big difference is the amount of "time" it takes for the fuel curve to stabilize after WOT. With the power valves in, there is about 1 sec where the curve goes lean, then fat, then stable. With out the power valves that same "time" is about 2 seconds. Also in that 2 seconds there are usually 2 spikes or a lot of instability. I have found with the power valves, I run about 13.5 to 14.5 to 1 at light cruise/tip in. My exhaust temps are usually in the 1350 to 1400 range. I don't get any lean surge until about 16.0 to 1. With out the power valves my plugs stay clean and at WOT I get 12.0 to 12.5 to 1 where my car makes the most power. I found that changing air bleeds can alter the curve and In my case not for the better. When I start to alter my bleeds, I see that the overall fuel curve starts to deteriorate in stability. Here is an example. A friend of mine had his carbs done by the "carb shop" for a blown solid roller 454 combo. Whether he is cruising, part throttle, off throttle or WOT his curve is almost a perfect flat 12 to 1. Mine varies at lot. I tried to make mine flat like his by removing the power valves and altering the bleeds. Every time I moved more than 5 to 6 bleed sizes the curve line would get really spiky when driving. (not stable) I was told this happens because the emulsion tube (and bleed) are made to a specific size (to emulsify the fuel) in relation to vacuum signal at the booster, booster tube size and design, venturi size, etc etc. He told me that when the carb shop does a carb all of these variables are "tuned" together and thus the flat curve. So altering the bleed may increase the fuel ratio but I don't know that it would make it pull more fuel. I do know that as you go down in air bleed size, you increase the tendency of carb to "siphon" fuel out of the booster after the butterflies close. But I would think you would have to go way way down in size for that to happen. I have been told that what I see on my curve print out is fairly normal for most street driven cars. I think Wolfplace has an lm-1 and dyno experience. Maybe he can expand on your issue here. I would go up a size or 2 in jet to get away from the 15 to 1. After that see what you WOT reading is. I have been told most cars make the best power from 12.8 to 13.2. Mine however likes the 12.5 to 12.0 area. I have also been told most cars get the best fuel economy in the 14.0 to 14.5 range. What are your WOT readings??? As stated in the post above, I too noticed a change (for the better) in the lm-1 readings when I switched to larger air cleaners and the filter lids. Monte.