Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2495750
05/14/18 12:07 AM
05/14/18 12:07 AM
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Joined: Aug 2003
Posts: 43,211 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,211
Bend,OR USA
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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
Last edited by Cab_Burge; 05/14/18 12:08 AM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2495774
05/14/18 12:56 AM
05/14/18 12:56 AM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
I Live Here
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I Live Here
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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
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2495800
05/14/18 02:23 AM
05/14/18 02:23 AM
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Joined: Jan 2003
Posts: 1,908 Nebraska
4406bbl
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,908
Nebraska
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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.
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2495896
05/14/18 11:47 AM
05/14/18 11:47 AM
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Joined: Jan 2003
Posts: 1,908 Nebraska
4406bbl
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,908
Nebraska
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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! 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.
Last edited by 4406bbl; 05/14/18 11:52 AM.
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 4406bbl]
#2495976
05/14/18 02:21 PM
05/14/18 02:21 PM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
I Live Here
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I Live Here
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Mass
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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
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2495986
05/14/18 02:43 PM
05/14/18 02:43 PM
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Joined: Jan 2004
Posts: 4,567 Motor City
6PKRTSE
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master
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Posts: 4,567
Motor City
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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.
1963 Belvedere 440 Max Wedge Tribute 1970 Charger R/T S.E. 440 Six Pack 1970 Challenger R/T, 528 Hemi 1970 Charger 500 S.E. 440 4 BBL 1970 Plymouth Road Runner 383 1974 Chrysler New Yorker 440 1996 2500 RAM 488 V-10 4X4 2004 3500 Dually Cummins 4x4 2012 Challenger R/T Classic.
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2496015
05/14/18 03:24 PM
05/14/18 03:24 PM
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Joined: Jul 2011
Posts: 959 Chicago
PurpleBeeper
super stock
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super stock
Joined: Jul 2011
Posts: 959
Chicago
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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...
70 Roadrunner convt. street car
440+6, NOS, 4-spd, SS springs
'96 Mustang GT convt. street car
'04 4.6 SOHC, NOS, auto, lowered
"Officer, that button is for short on-ramps"
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2496069
05/14/18 05:59 PM
05/14/18 05:59 PM
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Joined: Nov 2003
Posts: 10,228 Colleyville
3hundred
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I Live Here
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Colleyville
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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
'68 Fury Convertible '69 300 Convertible '15 Durango 5.7 Hemi '16 300 S Hemi
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 3hundred]
#2496098
05/14/18 07:02 PM
05/14/18 07:02 PM
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Joined: Dec 2007
Posts: 18,157 Mass
DAYCLONA
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I Live Here
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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 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
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: Challenger 1]
#2496857
05/16/18 03:43 PM
05/16/18 03:43 PM
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Joined: Aug 2011
Posts: 2,864 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,864
Pattison Texas
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When my 440 6 pack did that I did not have enough timing. Fried a nice set of TTI headers. ^^^^^^
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: CSK]
#2496898
05/16/18 05:38 PM
05/16/18 05:38 PM
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Joined: Jan 2003
Posts: 10,730 North Dakota
6PakBee
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Do you have power brakes? If so disconnect the hose, cap the fitting in the manifold and see if that makes a difference.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: 440 running lean on cyl 7&8 with 6 bbl?
[Re: 72demon416]
#2497500
05/18/18 12:09 PM
05/18/18 12:09 PM
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Joined: Jan 2003
Posts: 4,727 Moved to N.E. Tennessee
GomangoCuda
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Moved to N.E. Tennessee
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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? Several people have tried to explain to you that the front and rear idle mixture screws have to be set the same. 3/8 to 1/2 turn out from seated is typical. Do not try to set the front carb for best idle first. When you do that it is trying to feed idle fuel to all 8 cylinders from one carb which is why you wound up at 1.25 on it and then the rear wanted nothing. You have to adjust both carbs at the same time. I know it is a pain but when you think about it it makes perfect sense. Again, 3/8 to 1/2 turn out from seated on both carbs is typical not 1.25. Forget about the finger over the bleed trick. It is BS that was first printed in the early to mid 70's and repeated a 1000 times since then. Please forget you ever saw it. You never said what your initial and total timing is. This is critical. If you don't have enough timing at idle then you will wind up with the idle speed screw adjusted in too far. That will expose too much transfer slot and then the center carb will feed too much fuel and you will probably try to correct it at the mixture screws. You will be chasing your tail. You need 18 deg or more at idle before you ever start trying to set anything in the carbs. You will probably need to recurve the distributer to maintain the correct total timing.
In theory, there is no difference between theory and practice. In practice, there is.
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