Moparts
mechanical six-pack carbs.
Posted By: gearbanger
mechanical six-pack carbs. - 05/27/08 05:53 PM
I've got a nice set of the old mechanical six-pack holley carbs. After exhaustive research on the subject, its nearly impossible or not practical to convert them to the vacuum set-up as they were never built for it. With a stock cam and no headers on a 440, is it possible to use these carbs with decent driveability. Mechanical secondary anything has never been my choice for a driver, but this set-up is a little different. Any thoughts?
Posted By: JohnRR
Re: mechanical six-pack carbs. - 05/27/08 06:02 PM
you are correct , you can't change them to vac operated . you can drive with them on the street , but you might just sell them and buy a new set of vac carbs ?
Posted By: gearbanger
Re: mechanical six-pack carbs. - 05/28/08 01:49 AM
Sounds like the simplest solution. The price of three new Holleys however is likely out of my league. Anybody bought them lately?
Posted By: RUNCHARGER
Re: mechanical six-pack carbs. - 05/28/08 02:15 AM
I ran a set of those carbs with a mild cam 440 and they were unbelieveably great on the street. You say you have a stock 440, stock as in 1970 specs or 1978 specs?
Sheldon
Posted By: 70sixpkrt
Re: mechanical six-pack carbs. - 05/28/08 02:19 AM
I ran those carbs. on my old motor for about 3-4 yrs. They were a pain to dial in. I ended up taking them off and putting on a set of vacuum carbs. with ProMax stuff. Love the carbs. now.
Posted By: gearbanger
Re: mechanical six-pack carbs. - 05/28/08 02:22 AM
stone stock 1970 440 4Bbl. Not the HP version. a little bowl work on the 906's, fresh rings and bearings.
Posted By: Danan
Re: mechanical six-pack carbs. - 05/28/08 03:58 AM
I ran a set of mech carbs on the street for several years with no problems. They are great. I had them on a 340 with a .508" MP cam and 4.10 gear/4spd.
They are easier to run because the fuel lines can be removed in one piece for jet changes, etc. This is a HUGE advantage at the track.
You will need to jet them up and do the standard PV swap. You will also likely need to play with squirters for the center carb.
They have received a bum rap due to all those years of MP telling us to trash them and buy the vacuum carbs. Most people who have actually taken the time to tune them and run them REALLY like them. If you don't like a double pumper on the street, then you won't like the mech carbs.
Posted By: RUNCHARGER
Re: mechanical six-pack carbs. - 05/29/08 12:41 AM
I ran them with a stock 383 HP convertor, 3.23 gears and a mild cam with Six Pack slugs and ported, stock valve 906's (very close to a stock 70 440 magnum). I left the middle carb stock, I jetted the outboards down to whatever a 700 double pumper jetting was (I think I had to drop 5 jet sizes). You could kick that thing at 20 MPH and it would respond right now and break the tires loose with no bog whatsoever.
I have a new set of vacuum carbs on my 71 Road Runner right now and although it works pretty well it still is not as crisp as that mechanical setup was.
Sheldon
Posted By: jbc426
Re: mechanical six-pack carbs. - 05/29/08 04:06 AM
I sent my set of mechanical carbs to Pro-max and had them do their stuff to them including a rebuild. The 493 inch hydraulic cammed motor they are on dynoed out at 681 hp/682 ft.lbs of torque at 5500rpm. I assume the vaccum advance models would produce the same output. The differnce is in the drivability. I like the control I get with them. They do require some thought to use effectively, but they teach you how to drive them by the seat of your pants. Too much too soon, and you feel it. Crisp is a good word to describe the way they feel. A set of well set-up vacumn carbs don't require much skill. You just mash the pedal and they do the rest. Mushy sounds about right to describe the difference.
I ran a set of the mechanicals back in the late '70's early 80's and absolutely loved them. One day the outboards stuck open on the freeway, which gave me a feeling that I'll never forget. I had to stomp on the pedal again to get them to release. What a ride!
Posted By: Anonymous
Re: mechanical six-pack carbs. - 05/29/08 04:46 AM
Quote:
you are correct , you can't change them to vac operated . you can drive with them on the street , but you might just sell them and buy a new set of vac carbs ?
why not just use a progressive linkage? cheap/ easy/ fixed.
Posted By: gearbanger
Re: mechanical six-pack carbs. - 05/29/08 11:15 AM
As usual, lots of good informed opinions have come back to help out. Thanks Guys.
Posted By: rbstroker
Re: mechanical six-pack carbs. - 08/05/08 12:51 AM
I am intrigued by the idea of mechanical linkage opening my outboards instead of the stock vacuum. Is there a mechanical linkage conversion setup available for the stock 1970 six packs?
Posted By: jbc426
Re: mechanical six-pack carbs. - 08/05/08 01:00 AM
Some people used to use a mechanical linkage on the stock carbs to force them open before the vacum would kick in and do it, but with no accelerator pumps on the outboards you are going to have transition problems. Getting your vacum cabs set-up properly is a drastically better solution.
Posted By: Fastback67
Re: mechanical six-pack carbs. - 08/05/08 01:49 AM
A mechanical setup really needs accelerator pumps on the outboard carbs. There use to be a company called "Six Paks To Go" that did just that. You sent them your carbs and they modified them with pumps and squirters, and a mechanical linkage,etc. The parts required to do the job were almost entirely off the shelf Holley rebuild parts, with the exception of the linkage. A little drilling, a little grinding. They even relocated the idle screws for easy access.
Posted By: lewtot184
Re: mechanical six-pack carbs. - 08/05/08 02:02 AM
i ran a set of the mechanicals back in the early 70's. tuning was much simpler than the stock carbs because there wasn't any emissions garbage in the carbs. i used a progressive linkage and they drove quit well. from a performance stand point i preferred the vacuum carbs. the vacuum carbs seemed to have more mid-range power. probably due to the controlled opening rate.
Posted By: fastnos
Re: mechanical six-pack carbs. - 08/05/08 10:14 PM
Hi there. Do you have a complete setup right now, or just the carbs? Here is a sight, all tho it's for Ford Carbs, that has a lot of great pictures and technical info that might help.
http://www.gerlecreek.com/documents/tptechnical.htmOne question I have is do you know much about carbs right now? The reason I ask, is by time you get them on and tweaked just right, you will know the carbs inside and out. Some people buy a used setup and then pull their hair out because of problems (previous owners) which is sometimes why they were for sale in the first place. It takes a lot of perserverance to work and get them just right. But having said that, when they're right, they are AWESOME! You might have to mail order a few parts also, looking at where your from too. Promax and Quick-Fuel make great products that will cut your tuning probems/troubleshooting time to a minumum. If your not real familiar with tuning carbs, you may want to send them off to Promax and have them set them up initially. Promax has a dyno they can test each carb you send them prior to getting them back. It just depends on how comfortable you feel tinkering with them.
Here's a book on E-bay you may want to look at also. May be availiable other places on the 'net also. E-bay # 270261211020
Posted By: 72383cudaman
Re: mechanical six-pack carbs. - 10/29/11 03:36 AM
where can i get the progressive linkage for the mechanical carbs been looking but cant find anyone who has it
cudaman72383@hotmail.com
Posted By: Danan
Re: mechanical six-pack carbs. - 10/29/11 09:35 AM
The mechanical six pack set-ups DO have accelerator pumps on the outboard carbs!!
Regarding six packs: I cannot believe how much BS (mis)information is floating around the internet, repeated and passed on my people who have never owned/run a six pack. Same thing with 426 hemis...
Posted By: GomangoCuda
Re: mechanical six-pack carbs. - 10/29/11 03:17 PM
Quote:
where can i get the progressive linkage for the mechanical carbs been looking but cant find anyone who has it cudaman72383@hotmail.com
I don't think anyone has sold progressive 6pk linkage for many years. Occasionally linkage shows up on ebay but it is usually attached to set of carbs. Best suggestion is look at pictures of other peoples linkage and make your own. That's what I did.
Posted By: 70sixpkrt
Re: mechanical six-pack carbs. - 10/29/11 07:25 PM
I had a set brand new in the box that I sold about 6 yrs ago. I can not find pictures of it with the box and part number. Sorry.
Posted By: DaytonaTurbo
Re: mechanical six-pack carbs. - 10/30/11 12:01 AM
Quote:
The mechanical six pack set-ups DO have accelerator pumps on the outboard carbs!!
Regarding six packs: I cannot believe how much BS (mis)information is floating around the internet, repeated and passed on my people who have never owned/run a six pack. Same thing with 426 hemis...
Yes, the mechanical secondary six pack carbs do have accelerator pumps, because they need them. It's basically just a holley double pumper spread out over 3 carbs. You need that accelerator pump shot to help cover the transition. What you definitely don't want to do is redneck a mechanical linkage to a set of vacuum carbs. That would perform horridly. Like was mentioned already, there used to be a company that would convert your vacuum carbs to have accelerator pump and mechanical linkage. But my question is at that point why wouldn't you just buy a pair of holley 2300 series carbs and run them?
Posted By: Duster 371
Re: mechanical six-pack carbs. - 10/30/11 01:02 AM
Quote:
I had a set brand new in the box that I sold about 6 yrs ago. I can not find pictures of it with the box and part number. Sorry.
Holley part #s were 4782 and 4783 
Posted By: meepmeep70
Re: mechanical six-pack carbs. - 10/30/11 01:32 AM
bought vacuum carbs last year from summit,$440 for center$360 each outboard IIRC
Posted By: 70sixpkrt
Re: mechanical six-pack carbs. - 10/30/11 07:22 AM
Quote:
Holley part #s were 4782 and 4783
I was talking about the Edelbrock linkage. I sold the carbs and linkage at the same time. The linkage was brand new in the box and I had a pic of the Edelbrock part #.
Posted By: fastnos
Re: mechanical six-pack carbs. - 10/30/11 10:17 AM
I do not have any part number for the progressive linkage. If you know of anyone with some old "Direct Connection Catalogs" the numbers should be in there, along with the numbers for the carbs too. Might be a starting point at least. Here are a couple of pics from the net over past few years of different linkages...
Posted By: fastnos
Re: mechanical six-pack carbs. - 10/30/11 10:20 AM
1 more
Posted By: fastnos
Re: mechanical six-pack carbs. - 10/30/11 10:22 AM
and another...with vaccuum secondaries
Posted By: fastnos
Re: mechanical six-pack carbs. - 10/30/11 10:28 AM
Last one, might be able to track down one of these by old NOS number on different web sites...?
Posted By: fastnos
Re: mechanical six-pack carbs. - 10/30/11 10:31 AM
ok, maybe another one.
Posted By: jbc426
Re: mechanical six-pack carbs. - 10/30/11 01:10 PM
I ended up with a very nice and simple heim-joint linkage from Ben at Promax. Also, using #6 banjo fuel fittings with good result & clearance.
.jpg "6894771-'Cudaprepaint002(Large).jpg")
Posted By: Mr.Yuck
Re: mechanical six-pack carbs. - 10/30/11 03:18 PM
I'd think they'd work just as well but would require some tweaking. I think AutoZone can get you re-manned 6-pack crabs for $325 each. Or you can try and sell yours and bu a set of vacuums. In any event you're going to have to tune them.
Posted By: xs29j8
Re: mechanical six-pack carbs. - 10/30/11 04:09 PM
I ran three 250 CFM Holleys with a homemade linkage setup for almost a decade. The throttle response was incredible, the best I have ever had on a carbureted car. Basically it was a 750 CFM triple-pumper... Downsides were around town fuel mileage and top end power due to the 750 CFM limit... 13.6s@ 102 MPH. The carbs were meant for a 289 Cobra, and bought new at a swap meet in Houston for $40/set of three. On the end carbs, I had to cut down the extended air horns to clear the cross bars n the air cleaners.
Here's a photo of the setup:
Posted By: Mr.Yuck
Re: mechanical six-pack carbs. - 10/30/11 07:49 PM
Quote:
I ran three 250 CFM Holleys with a homemade linkage setup for almost a decade. The throttle response was incredible, the best I have ever had on a carbureted car. Basically it was a 750 CFM triple-pumper... Downsides were around town fuel mileage and top end power due to the 750 CFM limit... 13.6s@ 102 MPH. The carbs were meant for a 289 Cobra, and bought new at a swap meet in Houston for $40/set of three. On the end carbs, I had to cut down the extended air horns to clear the cross bars n the air cleaners.
Here's a photo of the setup:
hmm a neat trick would be to get 3 FoMoCo 550's and run them.
Posted By: lewtot184
Re: mechanical six-pack carbs. - 10/30/11 08:28 PM
Quote:
The mechanical six pack set-ups DO have accelerator pumps on the outboard carbs!!
Regarding six packs: I cannot believe how much BS (mis)information is floating around the internet, repeated and passed on my people who have never owned/run a six pack. Same thing with 426 hemis...
ain't this the truth! i made my own linkage back in the day.
Posted By: Cab_Burge
Re: mechanical six-pack carbs. - 10/30/11 11:24 PM
Quote:
Quote:
I had a set brand new in the box that I sold about 6 yrs ago. I can not find pictures of it with the box and part number. Sorry.
Holley part #s were 4782 and 4783
Stock jetting on the center carb, List # 4782 is 64 jets with a power valve and #31 squirter, the outboards call for #82 jets with #28 squirters. Measure the vacume in gear at a idle ROM and use a power valve lower than what it idles in gear(1 to 3 inches) 
Posted By: 72383cudaman
Re: mechanical six-pack carbs. - 10/31/11 01:03 AM
i found someone that is going to make me linkage if i dont like the mechanical ive got 2 vaccume bodys that only need the bases can pull the switch a roo ive read both sides mechanical really dont sound too bad the ones i just bought are from the 90's from paw ive read alot of good things about the newer mechanical secondarys im not afraid to crawl up the hood of my cuda and tune
