I need some opinions here. I installed a NEW 6 pack setup on my 440 with nothing but grief with this pile of poo. I have have been fighting cold start, no idle, low vacuum, major lean conditions from the start. I thought everything was pointing towards a vacuum leak but I have looked for one numerous times and that doesn’t seem to be it. I did find the throttle blades were not centred in the center carb base shaft and would not fully close leaving the idle transfer slot wide open and have now resolved that problem. I have gone through the carbs twice now and have the float levels correct, timing correct all the usual stuff you adjust and have it idling nice now and responsive just cracking the throttle but when I was setting the total timing at 2600 I noticed the #7&8 cylinder header pipes started to turn cherry red after a minute. So my question is why are these 2 cylinders lean? At a steady throttle with no load what is feeding them? the rear carb? or are they still running on the center?
The only other unresolved issue is my left idle mixture screw is almost unsponsive whereas the right functions as it should. The left idle screw DID get better somewhat once I got the throttle blades closing up but it’s still not like it should be but I don’t see that affecting my rear cylinder lean problems.
I have the center jetted at 64 and 1.5 turns out on the bleeds right now and set the outboards by covering the idle air bleeds and setting the mixture so that there was no change in rpm covered or uncovered. That worked out with the front base idle screws out about 1.25 turns and the rear carb wanted them closed right off- but these are idle settings anyways so I don’t see that having any bearing on my lean part throttle issue anyways.....or am I wrong on that?

Have you adjusted the idle fuel mixtures on both outboard carbs. yet? If not do that next, the idle mixture screws may have lead covers on them, there in the bases under the fuel bowls
I set my stock outboard carbs. up from 1/4 to 1/2 turn out from gently closed all the way
BTW, I'm assuming you have new Holley replacement carbs. and not some other brand, do you?
Let us know what you find, that will help others on here later

Yes I have the outboards done, the front was about 1.25 turns out on the base screws and the rears are closed right off. This was done covering the outer idle bleeds and adjusting until the idle speed did not vary. I’m a little surprised the fronts wanted that much while the rears wanted nothing.
These are the new replacement Holley carbs where the idle screws are in the base. Not real impressed by the quality control on them....
I certainly see why guys buy the metering blocks to upgrade the outboards carbs adjustability.

Sounds like you got quite a mess going on, I know you won't like it, but I'd start by pulling the intake and looking for a cracked runner IMHO, new Edelbrock 6 pack manifolds like to crack around cylinders 6, 7, and 8... but a crack could be anywhere, plus the Edelbrock BB sixpack manifolds are notorious for gasket sealing issues, what gaskets are you running?, plus a dry fit of the manifold is in order to check if it's mating with the heads/intake ports squarely

Yeah, it hasn’t been all that much fun so far. I like to tinker but that novelty is starting to wear thin now.
I used the fel-pro 1215 with the crossover blocked off.I have contemplated all along about pulling the intake as the valley pan gasket fit like a piece of **** (very distorted)and has always been on the back of my mind how well it sealed- yet no sign of a leak from it.
I never considered the intake cracking though....

All 6 bbls feed idle fuel, and idle fuel flows at 2600 rpm, actually it flows to some degree at all rpm. I would guess with the rear carb idle screws being closed that is a big part of your lean problem. I would try all the outboards at about a 1/2 turn and see if it helps the lean problem. I don't think you want no changes when you cover outboard idle bleeds, if you cover them and it should get rich and lose a few rpm if its right in my opinion. It is possible the rear metering plate idle gas feeds are the wrong size, or blocked, could be blocked or restricted in center metering plate also. You need to get all 6bbls helping with the idle, and it seems best with outboards at 1/4-1/2 turn, center at 1 to 1-1/2, actual mixture, idle air to fuel ratio is done with idle gas feeds and bleeds, more the gas feed than bleeds as drilling those is a good way to ruin a carb. Some of these newer 6bbl carbs are a nightmare.

If the rear idle circuits are contributing at that rpm then that would definitely make sense then! I’ll fatten up the front carb a bit (because I can get to the mixture screws) and then move it to the the rear and see what happens.
Thanks!

Did you follow the tuning guide for the set up?
Can some one post the tuning guide?

You really need to follow the baseline set up - this is a proven technique - we have an official six pak tuner tester on here [sogtx] that tests all the info. Check your intake fitment - do the bolts line up properly?
Probably not - you can use clay around the ports to check the gasket squeeze

Yes they contribute at idle and have a transition slot for when the outboards first open. Try to put all 4 outboard idle screws out the same amount. I would start at 3/8 or 1/2 and see where the center ends up.... if its less than one turn out on the center the rears need to be turned in more, more than 2 turns turn the outboards out more. A general rule is 1/8 turn on all 4 outboards =1/2 turn on center, not always a perfect ratio or all carbs but to help get you in the ballpark since its so fun adjusting that rear.

When the OP gets around to checking off just the basics, before attempting a tune on the carbs, a member here sells special base plate screws and the required tool to make adjustments, esp on the rear carb easier while running, simple swap... contact Bud Weaver at Sixpack Solutions (Moparts member 69sixpackbee)

Mike

I always adjust the center one first then get the front carb to wear I like it & then move it to the rear & then adjust the front one last again, makes it easier that way. I would also try that to see if your lean condition will now move towards the front of the engine along with the carb. The you know it's the carbs & not an intake issue.

The intake (appeared to) dry fit well but the valley pan DID NOT. In hindsight I should have checked it with putty.
Yes, I used the tuning guide and it WAS helpful but it does not address when things are out of the “normal situation” window. Like carbs that (1) adjustment screw does not function on, throttle plates not centred in the bores, 2 carbs that want radically different adjustments to run nice etc, etc,
If I can resolve the 2 cyls being lean by fattening up the rear carb I “might” be on the upswing.

I don't mean to add fuel to the fire, but hopefully this will help.
1. You will get there, be patient.
2. There is a good chance the intake is not sealed, underneath, in the back (cyl #7 & #8)
3. How do you know it's running lean on #7/#8? Plug reading?

When I was fighting my 6-pack issues, neither of my center carb idle screws did anything. I had the transfer slots uncovered, go the center carb more closed & then only ONE of my center carb idle screws did anything. I took the carb apart, cleaned everything & found a "glob of oil smutz" inside the metering body...cleaned it & both idle screws now work. Hope that little story help... I know you have new carbs, but...

If working on the carbs does not fix it look at removing the intake manifold and valley pan to see if the intake to the head fitment is good or wobbly
I take a feeler gauge and try shoving the thinnest to the thickest ones I can get to slide under the intake to the head on all four corners, top and bottom edges and write those number on each corner to see if there is a pattern or so the machine shop can machine the intake surface so it will sit flat on the heads
I do ask for a tiny bit(.001 to .0025) tighter, tapered, on the bottom sides than on the top so it will pinch the bottom tight against the heads and intake manifold I do have them cut a little bit more(.015 to .030) so I can use the thin fiber intake gaskets on the head side minimum, it doesn't hurt to use them on both sides of the valley pan if needed

You DID install a plug or vacuum fitting in the back of the manifold and hook up the vacuum lines? Yes, I've seen it left out and overlooked.

Robert

check the idle feed restrictions in the rear carb metering plates. sometimes they're not drilled properly. it's impossible to get the proper idle air/fuel mix in the center carb because the idle jet is too small and the idle air bleed too large. there's ways to reduce the air bleed size but opening up the idle jet requires "surgery".

It's funny, but not, at the same time, I've seen this as well on a few intake swaps/upgrades when asked to "look" at someones install/tune that's not running/running like crap.... I've also seen where some guys left the PCV hose that Holley ships the sixpack center carb with still hooked up to the bowl vent tube sucking the gas right out of the bowl and they wondered why it ran like crap or even stayed running... the OP should post some pics just so some eyeballs might spot something missed?, as the sixpack can be daunting to some not familiar with it's set up

Mike

Too many possibilities to sort out your issues long distance but one thing to be sure of is that the orifices in your end carb metering plates are not plugged or blocked by anything, if so you will have a bad lean condition as you described. Not typical with new carbs but if you had any crud in your tank its possible.

Are you making your adjustments with the outboard carbs disconnected from the center (both the linkage and the vacuum)? Sometimes the repro linkages going to the end carbs will partially open the throttle plates when connected (inside radius at the bend is wrong). The OEM linkages typically don't have this problem.

I’ve have checked that and the adjustment is perfect, there is zero pressure on the secondary throttle shafts.