Sorry as I did not realize you have to keep it from WOT for a bit. Then do what works best for you now. Course you may have to change the main jets later if you tune for WOT. I was also curious if you have both a primary and secondary power valve since jetting was 80 on all 4 corners ? I would guess it does have both power valves or someone has been in the carb before ? Ron

The carb came directly from Holley. I called them to verify the factory jet sizes. They mentioned 80 in all 4 corners and two 6.5 power valves. Why they used billet metering blocks with pressed in IFR does not make sense???

part # 076-851bk

I reinstalled the 6.5 power valves and went down on the primary jets from 80 to 78. Tested the car and found the AF at 11.8-12.5, I then changed the primary jets again from 78 to 76. The AF now is 12.5-13.1. Still runs good at cruise and no hesitation. Have not tested WOT yet. I am going to change the jets from 76 to 74 tomorrow. I left the secondary jets at 80 for now.

Where should my cruise AF be? I am thinking 13.5-14.5

I have the idle at 13.5-14.0.

I would not go to 74s without at least trying WOT with the 76s first. IMO it will probably be pretty lean with 74s at WOT...

""Where should my cruise AF be? I am thinking 13.5-14.5""
""I have the idle at 13.5-14.0""

You are doing the right thing by creeping up on the A/F ratio. Your cruise A/F "range" looks like a good target. Once you are in that range, test to see where the "lean limit" is on your combo. As you lean it out a little at a time, listen for detonation. Once you start to hear it, then you know what is the lean limit on your combo, then you can richen it back up a bit.

I think your idle may also be in a good target range, but once again, you need to test to see what the lean limit is to your idle too. Some can idle/cruise at 13.4 and some can idle/cruise at 14.4.

Nice job!!

If you decide to relocate your ifr here's a good read.
http://racingfuelsystems.myfunforum.org/Relocating_the_Holley_Idle_Jet_about18.html

It WILL be lean at wide open after pulling that much jet out. And it looks like it still needs even less jet. The OP says that he needs to avoid WOT for now, so continuing to test the cruise with less jet is not a problem.

The idle is okay right now and he is moving in the right direction on the cruise. Keep pulling jet until the cruise is clean. Then, when possible, drop the secondary linkage and start drilling the PVCRs until the WOT on the primaries is good. Opening the PVCRs bigger will replace the fuel being taken out with the smaller main jets. And it will want that additional fuel sooner now.

We usually go with a 9.5 or 10.5 power valve. You really can't get too quick of an opening. The reason it didn't need that early of an opening point before is because it was so rich already. Now that it is leaner on the cruise, it will need the additional fuel sooner.

The track is the best place to set the WOT, but initially shooting for low 13s will get it close enough to dial in without being too rich. It is easy to drill it richer, but harder to lean it back down if the holes get too big.

We have done quite a few Holley 3310s and double pumpers this way. They are always rich on the cruise. Pull jet until the cruise gets happy, open the PVCRs until the WOT gets happy, and get the power valve open in time to eliminate any lean stumble has always worked.

The most common mistake people make with Holley carbs is that they change the jets to control air fuel ratio at WOT. As Dave points out, the PVCR is what should control the "extra" fuel for WOT. It takes more work to do it right, but you end up with a better carb when you do it right.

With a DP carb you can also set up the secondary side to be richer since it usually isn't kicking in for freeway cruise anyway.

Yea but you cant do that if you block off the power valve's. For racing I prefer to block off the power valves. Ron

For tuning, you can use a power valve plug to take the PV out of the metering equation. If it is still rich at low speed cruse (Throttle just cracked), you should look at using a smaller Idle Fuel Restrictor (IFR). I would not use a larger air bleed because that will delay when the main metering starts to flow.
At high speed cruse (Throttle open past transition circuit) tune with the main jets.
Replace power valve plug with power valve and see how the AFR looks when transitioning from cruse to power.

Here is the update. I installed the 74 jets on the primary. The cruise went up to 13.0-13.5. Under load from cruise I started to notice the AR fuel at 15-15.5.

I went back to 76 jets on the primary. The best I can get the cruise is 12.8-13.2. When under load from cruise I see 13.5-14.0 on the AF. No hesitation, and feels happier. The issue now is the IFR's are fixed. I might have to look at other metering blocks.

Next I am going to install a vac gauge in the car and see what readings I have.

I am sure this will be okay to cruise around till I can test WOT.

what is the vacuum reading where you are going lean?
i would throw an 8.5 PV in on the primary side and see if it still goes in the 15.0 AFR area with the light-moderate load.
if so, then you probably need to open up the PVCR if you want to keep the leaner jets in.

if you're already getting the transition circuit cruise where you need it then the IFR's are probably fine as is.

The "under load" is where the PVCRs come in. They are the power enrichment circuit. Do not use the mains to set that. Continue to pull jet until the cruise gets happy. Then throw more fuel at it when under load with the PVCRs and give it to it sooner with an earlier opening power valve.

Do not mess with the IFRs now. If there is nothing wrong with the idle, then don't mess with them. The transition slot may need some attention after you lean out the cruise. But unless you have an issue with the idle, leave the IFRs alone. At least for now.

See how the engine likes a cruise A/F of 14-14.5. The tip-in from a lean and mean cruise to more load will be the next challenge after you get a happy cruise. But the transition slots, PVCRs, and power valve will address that.

You are clearly going in the right direction. Keep it up.

"" I installed the 74 jets on the primary. The cruise went up to 13.0-13.5.""
- You are going in the right direction!!

""I went back to 76 jets on the primary. The best I can get the cruise is 12.8-13.2.""
- You took a step backwards. 72 jets may get you in the upper 13's and 70 jets may get you into the low 14's. Keep testing

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""The "under load" is where the PVCRs come in. They are the power enrichment circuit. Do not use the mains to set that. Continue to pull jet until the cruise gets happy. Then throw more fuel at it when under load with the PVCRs and give it to it sooner with an earlier opening power valve.""

- This is what you want to do after you lean out the main jets to get your cruise A/F where you want it.

This carb is driving me crazy. I went down to 75 jets and it's still 12.8 - 13 af at cruise. If I get in the throtle at a light cruise I sometimes feel a small hesitation and the af goes lean to 14.5 then goes rich.
At various times when I leave a traffic light, from first gear to second shifting at 3000-4000 rpm it falls on its face and the af goes to 10.8.
I installed a vac gauge and cruising around just holding a constant speed at various speeds I see the vac at 15 inches.

I did a small wot pass and I saw 12.2 af.

What is next?

Current setup primary 75 and 6.5 pv
secondary 80 and 6.5 pv

80 mains.....11.8-12.8 cruise
78 mains.....11.8-12.5 cruise
76 mains.....12.5-13.1 cruise
74 mains.....13.0-13.5 cruise with slight hesitation




Why not continue to try smaller main jets and an earlier opening power valve?

499 stroker with a Holley 850 carb. I read the newer 850's were really 750's with an 850 TP. I've tried 750's on my 440 and they all seemed hard to tune,to rich at idle to lean at wot. very hard to get everything right. I put a pro form 950 body on an old 850 dp that uses the 850/950 tp and my combo has never ran better and every adjustment has been easy and responsive.

It just sounds like to me your carb is to small for your combo. you need more cfm IMO.

The OP may well need more CFM for maximum performance @ WOT, but he is trying to get his cruise happy. And there is no reason he cannot do that with an 850. The double pumpers are track oriented carbs which are very rich for street cars which is why the OP is being forced to change the tune so much.

But they can be tuned to give satisfactory street manners, just like a Dominator can.

And yes there would have been carbs that would be closer to what he needed right out of the box, but this is what he has and it can be made to work.

IF he wants to put the effort into it.

I don't know if you can tune a carb very well that is to small for the engine. I agree that you can lean it out.

Pick ur poison..