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  #1  
Old 08-18-2003, 01:58 AM
Mr. Trans Am Mr. Trans Am is offline
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Question Six Pack is mad at me

Not in the way you would think though. You can kick it and all 6 come on strong. Too bad I can't drive WOT all the time or else this post would be moot.

I got a 6 pack from a board member yesterday. Said it ran fine on a .509 cam 440, with only idle adjustments made. Otherwise box stock. Engine it was one is bad and only heard it run for a few seconds before the grinding noise got unbearable. That engine was a 68 440 HP and likely had higher comp than mine. Will know soon as I'm going back for it also when it gets pulled from the car.

My engine is a 74 440 and has a mystery cam, sounds like a .509 or .484 MP deal. After fixing a bunch of vac leaks and trying in vain to find more it held 5-6" of vac with a 4 barrel. Ran good but had slight hesitation off idle which I attributed to low vac signal. I think this motor has stock pistons and that might make it hard to ever get much vac out of it????

Anyway the 6 pack went on and started right up, idle fine. had gasket leak that was hard to pinpoint so I got real good at getting center carb off on the first day I ever fooled with one. Got that taken care of, started up again. Again idle fine.

Time for test drive. Felt good for first little bit. Got to good spot to kick it, again felt good.

Then trouble struck. Settle back down to 60 MPH. Engine starts to cough and sputter, turn around head for home, sounds awful think I might not make it. Out of frustration I put it too the floor, good idea and it runs good. Back down to normal speed and again sounds like Nike time.

Back at home car idles rough. Put vac gauge on it but can't get good fit on only port I find, shows little vac. Play with idle screws and nothing happens. Great I'm on main circuit. Except I screw them both all the way in and try to idle down to find idle circuit. End up with idle speed screw all the way off the lever and still idles same, play with screws get no change.
Guess it has 6 corner idle?

Find in the process of fixing leaks it has # 62 jets and 6.5 power valve.

Maybe change power valve?
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Old 08-18-2003, 09:27 AM
b-1ken b-1ken is offline
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Did you have a good fuel filter in line? If rust gets into the low speed metering circuits, it will run like you described.
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Old 08-18-2003, 09:53 AM
Mr. Trans Am Mr. Trans Am is offline
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yes, and it ran fine with the old carb just before this.
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Old 08-18-2003, 06:06 PM
sixpackgut sixpackgut is offline
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first thing is that power valve is way to high. if you were getting 5-6vac then it is open all the time. a sixpack does have 6 corner idle adjustments. the rods to the outboard carbs are adjustable so even if you turn that idle screw all the way out the outboards can still be open. floats need to be set correctly. center carb float set at bottom of the site hole while the outboards need to trickle out. you need to find the best vacumm while the car is in gear at idle. your ignition system sounds like part of the problem. i would start at 15* initial with 36-38* total. good coil, wires, plugs.

i have a similar cam and i have 5-6 vac in gear at idle and have a 3.5 power valve in my carb. i also have a 50cc acc pump on my car with #37 squirter. i cant remember the jets but mine needs to be leaned out anyway so that wouldnt help. i have the weakest springs in my vac pods also.
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Old 08-19-2003, 10:10 AM
b-1ken b-1ken is offline
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The idle mixture screws for the outboard carbs are beneath lead plugs which must be removed. I ran one of these on my 'Cuda back in the 70's. The carbs were new and it ran lousy off idle with piss poor throttle response. Chrysler had a bulletin for a six pack which required you to remove the lead plugs to access the idle mixture screws. This makes a BIG difference as the end carbs were way out with idle mixture. In addition, they wanted you to open up the idle feed restriction in the center carb. There were also some jetting recommendations as well. I don't remember all of the particulars, but I think just getting the idle mixture set on the end carbs will help. After I made the changes the engine ran great with real good throttle response. I didn't change the power valve from the original one. This was a track only car with a 320 deg. cam and it idled in gear just fine.
I know I'm going to take crap for this but I don't think the power valve has much to do with idle mixture. Especially with six barrels providing idle fuel. The majority of the metering for idle fuel is the mixture screws. The power valve can't possibly affect the idle mixture to any great degree. It just shunts additional fuel around the jets. The jets are very large compared to the idle mixture needle restriction. Think of it this way. You have a 1" pipe feeding water to your house. You open up a faucet so the water just trickles out (idling). Then you install an additional 1/2" line in parallel to the 1" line that's already there (power valve open). Do you think that the amount of water trickling out of the faucet is going to change by any appreciable amount? I don't think so. Virtually all of the pressure drop is at the faucet (idle mixture screws).
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Old 08-19-2003, 09:29 PM
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Luther Luther is offline
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My guess...sounds like something more than just a carb tuning issue. It may be possible that your outboard carb throttle plates are hanging open a little after you open it up and drop the throttle back down. May want to check your linkage to make sure it is not hanging up and that the outboards do close completely.
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Old 08-20-2003, 08:45 AM
b-1ken b-1ken is offline
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Quote:
Originally posted by Luther
It may be possible that your outboard carb throttle plates are hanging open a little after you open it up and drop the throttle back down. May want to check your linkage to make sure it is not hanging up and that the outboards do close completely.
This a good suggestion. I've had this occur with the secondary of a four barrel hanging open. In this case though, if the outboard carbs have idle circuits, wouldn't them hanging open just cause the engine to race at idle? That is assuming the outboard idle mixture screws were open enough to supply fuel.
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Old 08-20-2003, 03:53 PM
Mr. Trans Am Mr. Trans Am is offline
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I ended up finding trash in the rear carb. Now for the real tuning to begin........
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Old 08-20-2003, 04:25 PM
b-1ken b-1ken is offline
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Quote:
Originally posted by Mr. Trans Am
I ended up finding trash in the rear carb. Now for the real tuning to begin........
I'd take all three of 'em apart and clean them thoroughly. If they haven't been removed, remove the lead plugs that hide the idle mixture screws on the outboard carbs.
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