Adjusting Six Pack carbs...Timing, transfer slot size, idle screw adjustment

[GrandpaKevin]

I'm trying to adjust the carbs on a 440 Six Pack.
Engine is a fairly stock rebuild with Stealth heads and mild Lunati cam.
The car starts, runs and drives OK but I think there's room for improvement with the idle quality and drivability.
The idle seems smooth when the engine is cold but gets a little rough when the engine gets up to operating temperature.
I'm going to tinker with the carbs as I'm thinking of changing the power valve but I also suspect the used MSD Blaster coil might be an issue causing spark issues when it gets warm?

I'm using a Firecore distributor that that I set the advance limits to 14°
Initial timing is currently 22° with a total of 36.
I was able to turn the idle screw down pretty good which I thought was good for the correct transfer slot size, maybe too far, but the center carb still has very little change when adjusting the fuel mixture screws.
I do not have a lot of experience with this and admittedly I did not check the transfer slot size before installing the carbs so I plan to remove the carbs and check.
I was able to get some changes adjusting the mixture screws on the outboard carbs. Initially when covering the holes on top of the carb the idle would raise (lean?) I turned them in to 1/8" from closed and the idle now stays the same when covering the holes.

In doing research and reading the standard Six Pack tuning guidelines a lot is talked about making sure the transfer slot size is square to keep the car running in the correct idle circuit.
If I understand correctly once I get this transfer slot square by adjusting the idle/throttle blade screw I should NOT make too many other idle adjustment (1/8th max turn either way)with that screw as it will throw the transfer slot size off?
Further idle adjustment should be made with turning the distributor?

So I'm going to pull the carbs, check the transfer slot size and start tuning from scratch...float levels, fuel pressure, fuel mixture screws etc.

Am I missing something or doing it all wrong?

Thanks for any suggestions or advice.

[Cuda Cody]

What size jets are you running?

[GrandpaKevin]

64's in the center carb

6.5 power valve with 16-17hg vacuum at idle.

[Shane Kelley]

Power valve probably not a issue. Technically it should be a 8.0. Vacuum number divided by 2 = power valve size. Sounds like you have some really good vacuum.

You didn't say how fresh the carbs are. Sometimes the metering block gasket will shrink if a carb has been sitting or older rebuild. Once the gasket shrinks it starts covering and uncovering things it shouldn't.

You are correct that the transfer slot should be close to a square shape when installed. See pic below for reference. This is a newer 4 barrel carb but has the same type metering system as your 2 barrel.  This will cause a rich idle condition if to much slot is exposed. The carb will bypass the idle circuit. When a carb is right the idle mixture screws are usually somewhere in the 1 1/2 to 2 turns out. These are not set in stone numbers. Main jets have no effect below 2000 rpm. The metering system controls everything up to that point.

What rpm are you idling at and what rpm are you wanting? Does the exhaust make your eye's bleed?

[Shane Kelley]

Then there is this thread with a video.

https://forum.e-bodies.org/engine-transmission-and-rear-end/4/everything-you-wanted-to-know-about-6-pack-carbs/889/

[GrandpaKevin]

Power valve probably not a issue. Technically it should be a 8.0. Vacuum number divided by 2 = power valve size. Sounds like you have some really good vacuum.

You didn't say how fresh the carbs are. Sometimes the metering block gasket will shrink if a carb has been sitting or older rebuild. Once the gasket shrinks it starts covering and uncovering things it shouldn't.

You are correct that the transfer slot should be close to a square shape when installed. See pic below for reference. This is a newer 4 barrel carb but has the same type metering system as your 2 barrel.  This will cause a rich idle condition if to much slot is exposed. The carb will bypass the idle circuit. When a carb is right the idle mixture screws are usually somewhere in the 1 1/2 to 2 turns out. These are not set in stone numbers. Main jets have no effect below 2000 rpm. The metering system controls everything up to that point.

What rpm are you idling at and what rpm are you wanting? Does the exhaust make your eye's bleed?

Carbs were bought new about 15 years ago.

They were run on another 440 for a brief period of time then put back in their original boxes and stored for a few years.
Carbs are very clean and have very low hours on them.

I checked the gaskets when I jetted and installed the current power valve, I installed carbs with new base gaskets. 
I plan to install new Superformance bowl and metering plate gaskets when I pull the carbs again.
I also plan to change the power valve since the carbs are off.
the cam is a mild hydraulic that does produce good vacuum
https://www.summitracing.com/int/parts/lun-10230702lk

Car does smell a bit rich at idle.
I currently have center carb mixutre screws out about 1 1/2 but again not much change with adjusting the screws.
Car currently ildes around 1000rpm in gear(auto trans) much less and the car wants to stall when in gear.

So again I don't have much experince with setting the transfer slot but I guess once the transfer slot is set the idle/throttle blade screw should not be messed with much and idle should be set by timing?

Thanks all.

[GrandpaKevin]

Then there is this thread with a video.

https://forum.e-bodies.org/engine-transmission-and-rear-end/4/everything-you-wanted-to-know-about-6-pack-carbs/889/

Great video thanks!

[Shane Kelley]

With a cam of that nature you will never get a clean idle smell. Those always tend to be a little stinky at idle. What you don't want is burning your eye's standing around or behind the car.

Been a while since I messed with those carbs so I don't remember if there are any type of blade adjustments on the outboard carbs. If you could crack one of those open a little if needed would be a possible way to bring idle up. It might be a small screw coming from the bottom of the base plate. It' won't be anything like the center carb if it even has anything. Since you have a pretty versatile distributor you can definitely use timing to bring the idle up.  I have locked the timing on some cars at 36. That's what I am currently doing on both my cars. Both 340's. Some engine combinations will struggle to start doing that. Mine start fine but I am running mini high torque starters. You could try that. It will definitely bring your idle up and have killer throttle response.

[Chryco Psycho]

64's in the center carb

6.5 power valve with 16-17hg vacuum at idle.

VACUUM READING needs to be In  GEAR IF AUTO not just at idle

[jordan]

When I set up my carbs on my RB stroker, the Holley site recommended drilling a small hole in the throttle plate to get more air in while keeping the plate on the transfer slot.  Cleaned up my idle issues.  My engine doesn't make much vacuum though. 

[734406PK]

IMO if the engine runs well when cold and turns rough when warm, the carbs are rich. I would recommend cleaning/rebuilding all three carbs so you can tune them successfully. The six pack has idle fuel contribution from all six barrels (6 corner idle?)so the mixture screws need to be synchronized. The outboard carb throttle blades must be completely closed as well for tuning. The idle speed is controlled by the center carb only.  I have a similar engine build as yours with 14 In Hg  idle vac and runs smooth, no fumes. It took a bit of tweeking to get it that way but it wasn't that bad. Post back if you need help.

[Chryco Psycho]

Yes & NO , the speed adjustment is on the center carb only But there is a set screw in the outboard carbs accessable from underneath to hold the throttle plate open slightly & there are mixture screws in the base of both out board carbs that need to be adjusted as well , I generally set them @ 1/2 turn back from bottomed out , if the carbs are unmodified ther are behind domes plugs , I drill a small hole underneath & drive out the out the plugs as the factory settings are not always that good

[734406PK]

 I'm running Promax rear base plate that has the mixture screws angled out 45 deg or so. This allows easy access to the mixture screws with the carb on the engine so you can adjust with the engine running. A BIG plus and highly recommended.
http://www.promaxcarbs.com/
The front carb mixture screws are already accessible no problem there. (After you remove the lead plugs like CP says)
I looked up the cam specs for the Lunati Voodoo 704 cam:

220/226 duration @ .050
.475in/.494ex lift
112 LSA

A fairly mild cam that should produce a high manifold vacuum (16-17+ in Hg)
The Stealth cylinder heads with 80cc chambers should be producing some high cylinder pressure with this cam however the base timing at 22 deg BTDC seems high to me. I would expect something like 15 deg +-.
The 440-6 runs well with a 195 deg thermostat, helps with vaporizing the fuel at idle.

Here's one source for carb parts and tuning info, very knowledgeable staff (as mentioned in the video) and located on L.I. N.Y.:
http://www.allcarbs.com/tech.php?art=24

[GrandpaKevin]

Thanks for the replies

I didn't get much time to tinker with it over the weekend but I'm starting to think I might have underlying ignition issues.
It seemed the more I messed with tuning the carbs the worse it ran.

I'm using the idle mixture screws and special tool from SixPack Solutions so I'm able to adjust the rear carb's mixture screws without removing it. It never had plugs in the front carbs because they are repops?
I started with the mixture screws on the outboards at 1/8th turn open then moved them to 1/4 turn but again I think there are other issues I need to check before trying the adjust carbs any more.

I think the engine might be suffering from a weak spark.
The engine just sounds and feels weak like it' not running on all cylinders all the time.
It will idle OK but stalls when put in gear.
I pulled a couple plugs and they looked very dark and sooty?
The engine seemed to run much better when I first got it started but something seems to be deteriorating.

The engine wiring harness is new from Year One.
I'm using a new Hi_Rev brand factory type ECU and a dual field (4 pole) ballast resistor (which I had to use because the YO wiring harness was wired for it) and a MSD blaster 2 coil which was used but looked like new.
Will a factory type dual ballast resistor have isses with the Blaster 2 coil because of the OHM rating difference?
Firecore distributor and wires, most all wiring is new.

When tuning under the hood I normally use a push button remote starter wired into the starter relay to start the engine.
Towards the end I noticed the car would turn over but would not start using the push button on the starter relay, I had to go inside and start the engine using the key which the engine did start and run.
I don't have much wiring troubleshooting experience but could this be caused by a failing ballist resistor giving too low of volts on the lower run side?
Bad coil or ECU?
One recent event that might be important is when I took the car to have the exhaust installed a couple weeks ago I believe the ignition key was left in the run position(engine off) the entire time the exhaust was installed so something in the ignition system might have been hurt?
The car started right up and drove home OK that day but the engine just doesn't feel right...
I have available another dual ballast resistor off a currently running car along with a different coil and ECU I was thinking of swapping out to test.

For those who are good at electircal troubleshooting what suggestions do you have?
I've done some research on checking the OHM's on the ballast and OHM's and volts at the coil but I really am a rookie at electrical stuff.

Thanks for any suggestions or advice.

[Shane Kelley]

I'm not saying MSD Blaster 2 coils are junk. But I had a rash of bad luck with them this year. Maybe it was something with my combination of components or mounting position.
If you have access to a different coil I would try that first and see if anything changes.