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Author Topic: Six Pack issues and rebuilding  (Read 51101 times)

Offline Chryco Psycho

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Re: Six Pack issues and rebuilding
« Reply #315 on: December 08, 2014 - 09:26:02 PM »
The Idle screws look about right to me , the outboards are generally around 1/2 - 3/4 turn out & center carb around 1 turn out + or -
 The out boards should open smoothly so you should not feel them open , no bog or sag as they open any sag & they are opening too fast & going lean before the fuel flow picks up .

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Offline HP_Cuda

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Re: Six Pack issues and rebuilding
« Reply #316 on: December 09, 2014 - 05:11:06 PM »
"So how do you know when you have the right spring? Start with the stiff and when you feel it kick in on WOT you have the right spring?"

It's basically where you want the secondaries to open up at what RPM. I think you are fine exactly where you are with the silver spring.

If you have the silver/clear spring you have the stock springs in there and it should work fine. If you wanted to go stiffer/lighter here is the chart
to reference:

I know this shows for a chebby but it gives you an idea where it starts to open.

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Offline onebadfish

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Re: Six Pack issues and rebuilding
« Reply #317 on: December 09, 2014 - 10:50:24 PM »
This is a guide that has been around for a while....


Remember six pak engines run on the center carb and idle on all 3
The car must idle and run like a normal car before attempting any secondary action or wide open throttle passes.

A Good ignition system is required., MSD, Mallory or FBO mopar box, NO orange boxes or chrome boxes unless you know for sure it is early 80s vintage. Anything made after 1988 is questionable.

Quality distributor cap & rotor
High quality spark plug wires like Firecore 50s
Spark plugs of the proper heat range.

Vacuum adv distributor
The distributor phasing has been checked and corrected as necessary
THIS IS IMPORTANT
Distributor vacuum port on carb disconnected and plugged at carb

Make sure the timing is 15 - 18 deg btdc [advance] at idle. THIS IS IMPORTANT
Set the timing marks at 15 btdc and align the rotor with the cap-this is one reason the phasing was checked.

Car in neutral-auto or 4 sp, emergency brake set.
A good quality vacuum gage is required,
Connect vacuum gauge to manifold vacuum source.

ATTENTION -195 degree thermostat- ATTENTION
THIS IS IMPORTANT
If you run a lower temp thermostat, raw fuel will collect in the intake
That fuel then burns off in the cruise mode.
Unless you have a wideband air fuel meter you will not see this happening, but you will have problems getting it to idle and see the mixture go leaner in the cruise mode.

The heat crossover should be blocked on big & small blocks
Note: in temps below 40 degree it will take a good while to get the car warmed up. Block heaters will eliminate the long warm ups.

Set the outboards idle adj screws out 1/8 turn ccw THIS IS IMPORTANT
Be careful when seating the idle screws to set them, gently is the word
Install the BLACK springs Just do it, ignore everything else you have read

Set the center carb idle adjustment screws at 1.5 turns out [ccw] THIS IS IMPORTANT

Check the center carb and be sure to adjust the idle screw until the throttle blades are closed and the transfer slot is exposed no larger than a square. [carb would have to be off the car to see this] You only want about .040" of the transfer slots exposed below the throttle plates. If the idle screw is adjusted too high, you will be into the transition circuit, exposing too much of the vertical rectangular slot. Many times the idle screw is adjusted incorrectly to compensate for other issues. This puts the carb into the transition circuit and at that point you have no mixture control on the center carb.
If you have new carbs(untouched) they will have 62 jets in the center carb & a 6.5hg power valve The outboards will have the lead plugs covering the idle adj screws.

Starting point for center carb jetting stock 340 use 62s, highly modified or stroker use 64s,
Leave the outboards alone for now unless you have the jetable metering plates, if so read their instructions and follow them
You must know what power valve is in the center carb. Typically a 6.5

Fuel level adjustment THIS IS IMPORTANT, this is best done idling at 1000-1200 rpm
The slotted screw on top of the needle n seat is just a lock screw,
To adj the float level loosen the lock screw to rotate the seat nut,
Turning the adjuster nut counter clockwise will raise fuel level in the bowl, clockwise will lower it
Make only small 1/2 turns.
You must let the car run a 3 or more minutes so the fuel levels off before rechecking level
Center carb the fuel level is at the bottom of the sight plug hole
Secondaries it is just starting to come over the bottom of the sight plug hole
This is critical so get it right.

Set idle to 950 rpm and allow engine to reach operating temp.

Reminder 195 degree thermostat required or fuel will puddle in the intake. .

If the car wont idle: Is engine vacuum reading at least 2 hg higher than the power valve rating? If ok proceed, if not correct power valve issue and proceed.
Note some engines only pull 5 hg of vacuum so use a 2.5 power valve.

Now set the initial timing to where it wants to be. Somewhere between 10-20 degrees BTDC. The engine will tell you by increasing vacuum and rpm at this point. In some applications the engine does not care, so set it to 12-14 degrees BTDC.
Cams with 106-degree ctrlines seem to like initial timing set at 16-22 BTDC
Cams with 108-degree ctrlines seem to like initial timing set at 12-18 BTDC
Cams with 110-114 degree ctrlines seem to like initial timing set at 8-14 BTDC

Re-Set the idle rpm for 900-See if you have "control" over the idle mixture screws on the ctr carb. Using a good vacuum gage adj center carb mixture to highest reading of vacuum. If you do not have control over the idle mixture you have issues that need to be taken care of before proceeding.

Typically if you have the center carb idle mixture screws between 1 to 2 turns ccw
you do not have to adjust the outboard idle mixture any further. Starting with the front carb, adj the mixture screws one at a time 1/16th turn ccw, after turning each screw wait and see what the engine vacuum and rpm do. Obviously if you have a wideband a-f gauge you will see what is happening.

Beware of issues such as poor intake sealing, carb gaskets backwards, the wrong pcv valve, a vacuum leak from the brake booster or other places, wrong pwr valve etc.

Recheck idle rpm and set to 900

Drive car like a normal person, no wide open throttle. Is the car rich? Jet down 2 steps until you find the min jet size. You will know when you are lean as you will have no power.

Most times you are over jetted.... Do not over jet!
Over jetted carbs will have poor idle control.

Now reset the initial timing again. Somewhere between 10-20 degrees BTDC. The engine will tell you by increasing vacuum and rpm at this point. In some applications the engine does not care, so set it to 15 degrees BTDC.

Re-Set the rpm for 900-See if you have "control" over the idle mixture screws. Using a good vacuum gage adj each mixture screw to highest reading of vacuum. If you have a wideband afr meter set to 14.7

Recheck idle rpm and set to 850

How do you know when you are "there?
The car will idle at 700-900 rpm in neutral and the response is crisp.
There is no smell of raw gas in the exhaust.
The bottom of the intake is not soaked with fuel. Open a carb and look in
The spark plugs are clean.
The engine when cold starts easily, runs and drives smoothly from the get go.
The engine when hot restarts immediately without touching the throttle.
When the engine is revd and the throttle released it immediately returns to idle.

OK if you made it this far its time for the Secondaries

The reason you put the black spring is to delay the opening of the secondaries until the engine is ready for it. The engine will run fine on just the center carb till at least 3000 rpm. The air fuel mixture spikes lean when the secondaries open, but at higher rpms this is transparent and has no affect on performance. The opening of the secondaries should be seamless, but very apparent and usually scary to the uninitiated.

The long vacuum hoses for the outboard carbs need to be exactly the same length.

Pulling a vacuum on the hose should make the vacuum pod open the throttle blade and hold a vacuum

The best way to dial in the secondary air fuel ratio is with a wide band air fuel meter.
A fine tuned seatofthepantsometer and spark plug reading will work for the more experienced

If you made it this far and the car is bogging when the six pak opens you need to go back and recheck starting at the top.

Notes:

If the initial timing exceeds 12 degrees BTDC with a MP distributor typically the advance curve will need to be modified so the total timing is not more than 34 degrees BTDC.

Automatic cars with too tight of a converter will cause significant idle rpm drops when in drive, the car will not run at its full potential so be sure to use the correct converter for the application.

Some cars like staggered jetting.
 


Offline tommyg29

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Re: Six Pack issues and rebuilding
« Reply #318 on: December 09, 2014 - 11:44:48 PM »
Thanks guys.
I have seen those before.
When the new springs and diaphragms come in a few days Im going to compare the new springs to what I have because I see what looks like maybe some yellow at the top of one of the springs, and then Ill just test each one, maybe starting with the black, then brown, then plain, etc and use the first one that feels smooth.
One thing at a time, but I do think it is idling well now.
 
« Last Edit: December 10, 2014 - 12:01:20 AM by tommyg29 »
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92 Dodge Stealth RT-Twin 15g Turbos-SAFC2 Tuned-Mystic Blue-5 Sp-AWD-Rear Wheel Steering-AutoX'r (Sold)
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Offline tommyg29

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Re: Six Pack issues and rebuilding
« Reply #319 on: December 14, 2014 - 12:27:56 AM »
Still idling well, and now running much more smoothly under hard throttle without any "kick in". I replaced the lighter yellow springs and old diaphragms, and went straight to the silver springs. I think its still a little rich...I can smell it...but no more smoke and it seems every time I fiddle Im getting closer.
I feel like the tortoise.
I noticed a little off idle hesitation today maybe for the first time, and did get dieseling one time, plus the car does not return immediately to idle when blipping the throttle, but it never has. It tends to slowly come back down.
New and old diaphragms:
« Last Edit: December 20, 2014 - 11:55:38 PM by tommyg29 »
72 Roadrunner 400-4 Auto-3.23 Gear-Black Cruiser
71 Cuda 440-6 Tribute-Limelight-A833 Close Ratio-4 Sp-Pistol Grip-Dana 3.54 Powr Lok-Rally Dash-Shaker (Sold)
92 Dodge Stealth RT-Twin 15g Turbos-SAFC2 Tuned-Mystic Blue-5 Sp-AWD-Rear Wheel Steering-AutoX'r (Sold)
12 Dodge Charger SXT Plus Blacktop Package-3.6L-8 Sp-Leather-Nav (the wife's)

Multiple SRT's, Rams, Dakotas, Caravans and Neons

...the lines on the road just look like dots!....

Offline moper

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Re: Six Pack issues and rebuilding
« Reply #320 on: December 19, 2014 - 11:32:08 PM »
So how do you know when you have the right spring? Start with the stiff and when you feel it kick in on WOT you have the right spring?

And question two, I realize every engine is different, but for those that have tuned a bunch of these, what are the typical idle screw settings. My main is about 7/8 turn, and I have the secondaries at about 1/2 turn out (all equal side to side)

Hi Tommy - I haven't visited this site in a long time... First time seeing the thread and the 'ol girl. She still looks great! Th esprings, if my memory serves me right, is that it has two "short" yellow springs in the secondaries. You aill not see the secondaries open without a load on the engine, and the center going past about 1/2 throttle. You will want to go stiffer - not lighter. A lot of guys like the purple springs... The spring search requires you to test drive, swap, test drive, swap... You start heavy, and go lighter until you get a stumble, then go back one stiffer.
The run-on may be caused by carbon - a lot of fuel dumped and not burned well will carbon things up. Once it's right again try runnign some Sea Foam or some water sprayed down the carb when it's hot and running, or a chemical decarbonizer.
The idle screw setting is the best idle vacuum with the screws out an even amount. It could be 1, 1 1/2, or 2 turns... Whatever it likes. Use a vacuum gage to set them. Your ear will deceive you. Also bear in mind the air bleeds may not be right for the engine either, which means the idle will only get "so good" unless you make changes there.
I miss that car - but glad to see you still have it and it's working for you.

Offline tommyg29

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Re: Six Pack issues and rebuilding
« Reply #321 on: December 20, 2014 - 10:06:53 PM »
Nice to hear from you moper.
 I think you were the last to tune these carbs. I removed the copper wires you had in the bleeds, but I reinstalled them recently.
I am now running the silver springs. They seem to work best, and you have a good memory...they were yellow springs.
I doubt you have read this entire thread, but I actually have replaced all three carbs with used running units, swapping for all the best parts of the bunch. It had the 340 outboards before but now has the big block outboards, but there doesnt appear to be much difference in the two. Jets are much smaller but it does seem to still run rich. I have sprayed water a couple times and keep fiddling. Maybe I will try the seafoam soon. The more time I spend the better its running. Took it on a nice drive today and it ran very well, and idled great at about 800-900 rpm, but it dieseled a couple times after turning it off, and then seeing the smoke belching out the shaker.
It's running well enough, but the crisp immediate return to idle is something its never had, and dont know if I'll ever get there.
But it still has a good home, and I'm trying to do my part  :cheers:
« Last Edit: December 20, 2014 - 11:14:51 PM by tommyg29 »
72 Roadrunner 400-4 Auto-3.23 Gear-Black Cruiser
71 Cuda 440-6 Tribute-Limelight-A833 Close Ratio-4 Sp-Pistol Grip-Dana 3.54 Powr Lok-Rally Dash-Shaker (Sold)
92 Dodge Stealth RT-Twin 15g Turbos-SAFC2 Tuned-Mystic Blue-5 Sp-AWD-Rear Wheel Steering-AutoX'r (Sold)
12 Dodge Charger SXT Plus Blacktop Package-3.6L-8 Sp-Leather-Nav (the wife's)

Multiple SRT's, Rams, Dakotas, Caravans and Neons

...the lines on the road just look like dots!....

Offline moper

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Re: Six Pack issues and rebuilding
« Reply #322 on: December 23, 2014 - 03:44:19 PM »
But it still has a good home, and I'm trying to do my part  :cheers:

I'll start an investment acount for the day you decide your knee hurts too much to keep driving it :D....lol

Offline tommyg29

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Re: Six Pack issues and rebuilding
« Reply #323 on: December 23, 2014 - 09:37:39 PM »
Between playing football at the park with my kids home from college, and then doing a brake job last night (in the driveway, not a lift) on my sons Ram with 26 inch wheels that weigh about 80 pounds each, my knees are already crying.  :eek4:
Merry Christmas everyone!
72 Roadrunner 400-4 Auto-3.23 Gear-Black Cruiser
71 Cuda 440-6 Tribute-Limelight-A833 Close Ratio-4 Sp-Pistol Grip-Dana 3.54 Powr Lok-Rally Dash-Shaker (Sold)
92 Dodge Stealth RT-Twin 15g Turbos-SAFC2 Tuned-Mystic Blue-5 Sp-AWD-Rear Wheel Steering-AutoX'r (Sold)
12 Dodge Charger SXT Plus Blacktop Package-3.6L-8 Sp-Leather-Nav (the wife's)

Multiple SRT's, Rams, Dakotas, Caravans and Neons

...the lines on the road just look like dots!....