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.
What size jets are you running?
64's in the center carb
6.5 power valve with 16-17hg vacuum at idle.
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?
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/
Quote from: Shane Kelley on September 18, 2017, 09:14:29 AM
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.
Quote from: Shane Kelley on September 18, 2017, 09:23:40 AM
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!
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.
Quote from: GrandpaKevin on September 18, 2017, 08:37:52 AM
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
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.
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. :bigthumb:
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
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
Thanks for the replies :ohyeah:
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.
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. :alan2cents:
Quote from: GrandpaKevin on September 25, 2017, 11:11:55 AM
Thanks for the replies :ohyeah:
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.
I'll do some research on your ignition set up, but you are on the right track! Carb adjustment is the last step in the tuning process, everything else must function 100% first. I agree, i think you have another problem that needs to be corrected first before carb adjustment. Good info on the ignition issue! I'm not sure if the ignition components you have are all compatible, but will check. The best way to test a coil w/o expensive equipment is to replace it with a known good coil. What you don't want to do here is make unnecessary and irreversible mods to your carbs to compensate for an engine problem. :bigthumb:
This info popped up on the JEGS Site:
Coils made for C-D ignitions (MSD, etc) may destroy the Ignition Control Unit. Coil Primary resistance should be no lower than 1.4Ω
http://www.jegs.com/i/JEGS-Performance-Products/555/40805/10002/-1?CAWELAID=1710882104&CAGPSPN=pla&CAAGID=39714413703&CATCI=pla-293995373017&CATARGETID=230006180039220954&cadevice=c&gclid=CjwKCAjw0qLOBRBUEiwAMG5xMHnJ2ThaKr28LKSBDesHEoY3cjZOWt9EVlSIs32oyP9OS8hOq_B4HxoC3QUQAvD_BwE
And this from Mancini Racing:
http://www.manciniracing.com/msdblascoilr.html
Thanks for the info.
Unfortunately the other coil I have is also a older MSD Blaster 2, it has always worked well on the other car with an older chrome box ECU but I think I'm going to get a new, more stock type coil at the parts store.
https://shop.advanceautoparts.com/p/driveworks-ignition-coil-26189/10703783-P?searchTerm=+coil
Quote from: GrandpaKevin on September 25, 2017, 06:33:38 PM
Thanks for the info.
Unfortunately the other coil I have is also a older MSD Blaster 2, it has always worked well on the other car with an older chrome box ECU but I think I'm going to get a new, more stock type coil at the parts store.
https://shop.advanceautoparts.com/p/driveworks-ignition-coil-26189/10703783-P?searchTerm=+coil
:bigthumb: Check the resistance on the primary side of the replacement coil. Hirev wants 1.4 ohms or higher to limit current flow.
Quote from: 734406PK on September 25, 2017, 06:44:48 PM
Quote from: GrandpaKevin on September 25, 2017, 06:33:38 PM
Thanks for the info.
Unfortunately the other coil I have is also a older MSD Blaster 2, it has always worked well on the other car with an older chrome box ECU but I think I'm going to get a new, more stock type coil at the parts store.
https://shop.advanceautoparts.com/p/driveworks-ignition-coil-26189/10703783-P?searchTerm=+coil
:bigthumb: Check the resistance on the primary side of the replacement coil. Hirev wants 1.4 ohms or higher to limit current flow.
Well that's where my electrical inexperience comes in.
I think the paperwork that came with the HiRev describes how to test that with an OHM meter?
No Problem! Connect an ohm meter between the positive coil terminal and the negative terminal (where the ICU connects). Read the ohms value. It must be 1.4 ohms or more Use an accurate digital ohm meter so you don't have to worry about reading the right scale on an old analog meter (needle style).
Here is a coil from Pertronix that meets the spec:
http://www.jegs.com/i/Pertronix/751/40011/10002/-1
OR better yet, an epoxy filled version:
http://www.jegs.com/i/Pertronix/751/40111/10002/-1
A coil check might be worthwhile before tearing down six pack carbs.
A post I made previously on another site which seems relevant:
I have done some more digging and it seems if you go with an ECU setup you will need to protect both the coil and the ECU. Hence the ballast resistor comes to the rescue.
I have the MSD Blaster 2 coil which has a .700 ohms resistance in it already. This is why MSD will sell you a .800 ohm resistor for a total of 1.5ohms which would put you at 8 amps for a V8 (acceptable - read below). So (for example) if you have a stock 1.2ohm resistor with a MSD Blaster 2 coil then you are at a total resistance of 1.9ohms which would affect spark. You could swap out the ballast resistor for one that is .8ohms and should have better performance and longevity.
Ymmv,
B
This is a good read for those wanting to know:
What type of coil can I use with the Ignitor�? How do I check my coils resistance? (12V negative ground only)
To determine if your systems coil is compatible with the Ignitor, some measurements should be taken prior to installation of the Ignitor. Caution� While performing this test, never leave the ignition switch on for more than 30 seconds at a time.
Set your voltmeter to a 15 or 20-volt scale. Attach an 18 or 20 AWG jumper wire from the negative coil terminal to an engine ground. Attach positive (red) lead of your voltmeter to the positive side of the coil, and the negative (black) lead to an engine ground. Turn the ignition switch to the run position. Now read the voltage at the positive coil terminal. Turn the ignition switch off. If the voltage measured is approximately 12 volts, no resistance wire is present. A typical resistance wire will provide 9 - 6 volts.
The next step is to determine the resistance in the primary ignition. Label the wires attached to the coil terminals and note their appropriate location. Make sure that the ignition switch is off and disconnect all wires from the coil. Adjust your meter to the lowest ohm scale. If you are using an analog style meter make sure to zero the needle.
Measure from the negative terminal to the positive terminal. Write your measurement down.
Now the maximum system amperage can be determined, divide your voltage measurement by your coil resistance measurement. This will give you the system current or amperage.
Four and six cylinder engines should not exceed 4 amps. Eight cylinder engines should not exceed 8 amps. If the total amperage in your system is higher than the amount recommended for your application, you should install a ballast resistor.
Example
Voltage 12
Resistance 1.5
12 / 1.5 = 8
Total amperage 8
Thanks for the replies, I'm still trying to comprehend all this electrical stuff but the info is very helpful.
If I understand right my current MSD Blaster 2 coil has a built in resistance of .700ohms (do all Blaster 2 coils have this?).
I haven't checked yet but my current stock type 4 prong dual ballast resistor should be around 1.2ohm during the run mode.
So combined with the Blaster 2 coil the total resistance is around 1.9ohms?
Would that make a noticable difference in the way the engine runs and idles?
I do have the .800 resistor that came with the Blaster coil but it is a 2 terminal and I really don't want to start cutting the wiring on the new YO engine wiring harness unless I have to. I've also heard from multiple people the quality/dependabilty of the Blaster 2 coils isn't the best so maybe a different brand coil is the better way to go.
As far as buying a new coil the 2 linked Pertronix coils with a 1.5ohm rating is correct for my current dual ballast resistor's 1.2ohm rating?
I'm currently mounting the coil horizontally in the correct Six Pack coil bracket on the intake, I've done this on other cars with no coil issues, is the epxoy filled coil a better choice or is it overkill?
Thanks again and keep the comments coming. :twothumbsup:
Remember higher resistance means you will have less - 12/1.9 = 6.31
On a side note the MSD blaster coils are meant to be mounted vertically so at first they will work fine but will fail over time. You may want to get a coil you can mount horizontally if that's what you want.
The MSD Hi vibration coil can be used horizontally . https://www.summitracing.com/parts/msd-8222/overview/
OK this is where I am confused.
What am I missing.
The above linked Pertronix Flame Thrower coil is listed at 1.5 ohm Primary Resistance?
Am I understanding right that this is even a higher resistance than the current Blaster 2 coil at .700ohms or is the .700ohm resistance something else?
So the 1.5 Flame Thrower coil with my current 1.2 dual field ballast would put the total resistance at 2.7 total resistance?
12/2.7=4.4?
Thanks.
With the pertronix you could basically eliminate your ballast resistor.
I don't think you want to do that so settling on a coil which has lower resistance and can be mounted horizontally could be your ticket:
https://www.rockauto.com/en/catalog/plymouth,1970,cuda,7.2l+440cid+v8,1231759,ignition,ignition+coil,7060
Running without a ballast seems to be a hotly debated topic. :pokeeye:
So what coils are people using with the dual field ballast resistors?
Check the installation notes on the Hi-Rev brand ignition module. It states not to use a coil with less than 1.4 ohms primary resistance and they recommend a 1.0 ohm ballast for street use as well. Its unclear if you add the coil resistance and the ballast, or if their module will handle 8 amps. You may want to call the supplier for more info.
http://www.jegs.com/i/JEGS-Performance-Products/555/40805/10002/-1?CAWELAID=1710882104&CAGPSPN=pla&CAAGID=39714413703&CATCI=pla-293995373017&CATARGETID=230006180039220954&cadevice=c&gclid=CjwKCAjw0qLOBRBUEiwAMG5xMHnJ2ThaKr28LKSBDesHEoY3cjZOWt9EVlSIs32oyP9OS8hOq_B4HxoC3QUQAvD_BwE
Thanks for the link.
This is getting more difficult.
One of the items I want to check is the HiRev ECU, as I mentioned earlier the ignition switch was accidentally left in the run position for a few hours while the car was at the exhaust shop.
I'm not sure if the ECU, coil and/or distributor was damaged, the car did start and drive home.
I have an orange ECU and a Mopar electronic distributor that was running good on the car previously that I might swap in.
I wish I had more free time to tinker with the car but right now it's not happening.