Moparts

440 sixpack carbs

Posted By: Swiss_Robert

440 sixpack carbs - 04/17/11 11:00 AM

Hi! Last week I was able to fire up my 1970 Challenger 440/sixpack MT clone again after some years of (lazy) work - while the engine was NOT part of that work (but got a new exhaust system from Accurate - if you're interested: http://youtu.be/wU3zEr-ulvI ).

Now I'm dealing with the carbs. They look very worn and my first problem is that I don't get a stable idle. Engine goes up and down at idle and often dies. When I drove the car earlier, cruising or accellerating was not a problem - just idle.

I found https://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=4572020&Main=4569194 but this just helped half way...

I took the center carb apart and it looks worn inside, too. The shaft in the baseplate has play of about 0,15mm (0,006 inches)which feels like a lot. The choke shaft also has a lot of play and it's outside lever is loose. It has a lot of signs from earlier "human interventions" (like screwdriver marks at jets). It's dirty, throttle flaps got rust ... and so on.

Is such a worn carb worth to rebuild (or "renew" using the appropriate kit)? A new would be about $515 (and they are NEW, from Holley - not "professionally rebuild").

I'm considering just to replace the center carb and leave the outboarders or spend them a rebuild kit. Good idea?
Posted By: lokalik

Re: 440 sixpack carbs - 04/17/11 02:40 PM

check harms, i think they are a site sponsor
Posted By: screamindriver

Re: 440 sixpack carbs - 04/17/11 03:10 PM

The 6-bbl carbs are tricky to get right...That carb throttle shaft should have teflon seals on each side of the throttle bores...If they're shot or missing completely you'll have a massive vacuum leak from the beginning....But if the shaft and/or bore is wore too hard you're better off with new or sending them out... You can't go wrong using Harms...Scott does excellent work....I guess the ride back and forth from over there would be a factor going the rebuilt route
Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/17/11 03:23 PM

Your choke issues are normal,the main body,metering block and bowl (unless needle/seat threads are stripped) don't go bad.Some play in the throttle shaft is normal and can be bushed if needed.The biggest problem I have found is bases not square by being over tightened,also an easy fix.From what you describe,I would check for vacuum leaks before I would consider replacing the center carb.If you are using the thin black base gasket and your base is not square,it "will not" seal.I did thirteen 6pk sets last year and six since mid December,very few had based that didn't need milled.
Good luck.
Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/17/11 03:55 PM

Quote:

The 6-bbl carbs are tricky to get right...That carb throttle shaft should have teflon seals on each side of the throttle bores...If they're shot or missing completely you'll have a massive vacuum leak from the beginning....But if the shaft and/or bore is wore too hard you're better off with new or sending them out... You can't go wrong using Harms...Scott does excellent work....I guess the ride back and forth from over there would be a factor going the rebuilt route



I may be missing something but I have yet to see a production line set of unmolested 6pk carbs with the Teflon seals ever though the shafts are cut to accept them.I've seen them on a lot of 4bbl's,not all and a few over the counter replacements but never an original.
Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/17/11 09:34 PM

Quote:

The biggest problem I have found is bases not square by being over tightened,also an easy fix.


Sounds plausible.

I found quite some leftovers of yellow, crusty material between carb body and manifold-gasket...

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Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/17/11 09:35 PM

And on the gasket of course...

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Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/17/11 09:39 PM

Do you recommed to use another, a "thicker" gasket - or only grind it flat?

I tried to make a pic that shows backlight coming thru under my ruler... but it's not to good...

Outboarders will probably leak too, right?

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Posted By: GomangoCuda

Re: 440 sixpack carbs - 04/17/11 11:11 PM

I would machine all three bases and buy a new manifold.
Posted By: screamindriver

Re: 440 sixpack carbs - 04/18/11 01:09 AM

Quote:

Quote:

The 6-bbl carbs are tricky to get right...That carb throttle shaft should have teflon seals on each side of the throttle bores...If they're shot or missing completely you'll have a massive vacuum leak from the beginning....But if the shaft and/or bore is wore too hard you're better off with new or sending them out... You can't go wrong using Harms...Scott does excellent work....I guess the ride back and forth from over there would be a factor going the rebuilt route



I may be missing something but I have yet to see a production line set of unmolested 6pk carbs with the Teflon seals ever though the shafts are cut to accept them.I've seen them on a lot of 4bbl's,not all and a few over the counter replacements but never an original.

Guess you did'nt see them all then...
Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/18/11 02:31 AM

Quote:

Quote:

Quote:

The 6-bbl carbs are tricky to get right...That carb throttle shaft should have teflon seals on each side of the throttle bores...If they're shot or missing completely you'll have a massive vacuum leak from the beginning....But if the shaft and/or bore is wore too hard you're better off with new or sending them out... You can't go wrong using Harms...Scott does excellent work....I guess the ride back and forth from over there would be a factor going the rebuilt route



I may be missing something but I have yet to see a production line set of unmolested 6pk carbs with the Teflon seals ever though the shafts are cut to accept them.I've seen them on a lot of 4bbl's,not all and a few over the counter replacements but never an original.

Guess you did'nt see them all then...



Show me !

Here is another original A12 set,never been apart,I can take another set apart if you wish.You're not that far away,you can even come and watch or I'll meet you half way and we'll do it together!

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Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/18/11 02:32 AM

Nor any of these.I would think in 30 + years of doing them I would have found at least one set.

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Posted By: quick77rt

Re: 440 sixpack carbs - 04/18/11 03:14 AM

I just went out and looked at all mine from nos to nos 82/83 dc carbs, to pos ones, not one seal...can you post a pic or ???

If they can be had id like to get some, one thing I did notice is the very rough (open pits) in the cast base where these would be.
Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/18/11 04:49 AM

These are from old Holley 4bbl parts carbs,never tried to get any,possibly may be able to get from Holley.

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Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/18/11 09:40 AM

Quote:

I would machine all three bases and buy a new manifold.


I guess I will let machine all three bases, look for a fatter gasket and go with the manifold I have...

And try not to overtighten the attaching screws.

So feel free to quarrel about those seals

But thanks anyway!!!
Posted By: BSB67

Re: 440 sixpack carbs - 04/18/11 11:15 AM

I have taken the base and flattened them by using wet/dry sand papaer wet on a flat surface. I use a thicker gasket with a little sealant, and use very little torque to tighten them down, checking to make sure that the shafts turn freely.
Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/18/11 11:39 AM

That's at least !

I guess it takes warm-proof sealant? And should be used very thrifty?

Did you cut a thicker gasket yourself?
Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/18/11 02:01 PM

Will this gasket , Holley partno 108-52 fit? Onto the sixpack manifold?

Someone tried? Pros'n'cons?
Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/18/11 02:21 PM

All I've ever used is the original Chrysler fiber/cardboard gasket,1/32" thick,never had a problem.Still available through a dealer,pt.# P4529060,includes three each base and air cleaner gaskets.Also,being that your manifold has been modified,I would remove the center portion of whatever gasket you use to match the intake.

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Posted By: quick77rt

Re: 440 sixpack carbs - 04/18/11 02:34 PM

I think they do still sell just the complete lower portion (base) your concerned about and they have the throttle blades already installed. They did a year ago.

I use thick ones like them but without the flap for the carb to base seal and they work well.

In one of my setups I get lucky enough to use 9 gaskets, 6 thin between all the aftermarket plates and the 3 thick ones for the carb to top plate for the good seal and to help keep heat from building up in the carbs.

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Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/18/11 04:58 PM

You can also get all the parts and pieces from Chicago Corvette,and usually cost less than buying from Holley.

http://www.chicagocorvette.net/

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Posted By: 62maxwgn

Re: 440 sixpack carbs - 04/18/11 05:01 PM

End carbs.

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Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/18/11 09:42 PM

Quote:

Also,being that your manifold has been modified,I would remove the center portion of whatever gasket you use to match the intake.



There are walls removed out of the manifold, are they? I just wondered a second about that but did not realize that it has been modified in all three intakes - I was just focused onto the carbs.

Why someone would do that? What's the result, how does it change behaviour of the engine?

Do you recommend me to replace it? May be against aluminum like that ?
Posted By: 70sixpkrt

Re: 440 sixpack carbs - 04/19/11 02:33 AM

Call Promax carbs. They sell the base and gaskets.
Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/19/11 08:27 AM

Quote:

Call Promax carbs. They sell the base and gaskets.


Tried it by mail - I ALWAYS try the Moparts sponsors first. But they should read their mail.

Calling is experienced to be *hard* for non native english speakers ... last time someone explained me a hell of a lot of things over minutes and minutes that I couldn't really follow .

Thanks to you all for your efforts! I better don't imagine how my project would go without moparts...
Posted By: hemi68charger

Re: 440 sixpack carbs - 04/19/11 12:29 PM

Quote:

And on the gasket of course...



First, get the proper choke thermostat if the one in the picture above is what you have, it's incorrect. Maybe I'm missing something, but how's the motor spec'd out? Cam? heads? power brakes hooked up? Possible vacuum leaks other than the baseplates? Typically on 440's with pretty much stock cams and no vacuum leaks, they should purr like a kitten all day long, yet put you in the back of your seat when you open them wide open.
Posted By: Dads70RTConv

Re: 440 sixpack carbs - 04/19/11 01:26 PM

I know this isnt cheap but when my dad restored his six pack he sent everything back to holley and had them redone there
Posted By: Swiss_Robert

Re: 440 sixpack carbs - 04/19/11 02:18 PM

Yeah, well... there are a number of parts that are not correct at that car (call it my shameful old bucket). When I bought it in 2001 (for quite a reasonable price)I knew that it's a clone. But I wanted it . Then I started in 2007 to "repair only the transmission".

Now after all the time I found incorrect parts everywhere - and decided to leave alone whatever works and looks well . I was very satisfied with the engine, it pulled a hell of hard and cruised well - only idle was not reliable .

I'm very surprised (one time more) that the manifold was modified. After googling a while I found out that some people did/do that with that particular manifold ("notch out the dual plane divider" - while removing it entirely is not exactly that) to rise top end performance. I think I leave the manifold since I really cannot say the engine is weak at low end.

Choke just worked - however it opened the flap when hot and that should be alright.

I also checked the outboarders in the meantime and found that the rear was tight while the front had a small leak too, but not that much like the center, which indeed had a wide leak. It's perfectly visible when checking the old gaskets if they were seated between surfaces or not.

So I'll give it a try to just sand down the baseplates of center and front and apply a renew set to the center. May be I'll cut a bit fatter gaskets for the baseplates myself - can't take a 1/4" spacer since it's very, very tight under the hood. I think sealant is not the best choice since it's hardly gas-resistant.

And I'll replace all the rubber hoses against fresh. Have manual brakes, so no leak possible there.

I assume the engine may be more stock than not - not too seriously modified. There are still hydraulic lifters in, that's what I could see with valve cover off. I really don't want to take it apart when it runs that good.

I'll see how the first try works ...
Posted By: GomangoCuda

Re: 440 sixpack carbs - 04/19/11 02:57 PM

Quote:

Do you recommend me to replace it? May be against aluminum like that ?



You can save $100 by purchasing it as an Edelbrock instead of Mopar Performance. Same exact manifold, just bypassing one of the middlemen. http://www.summitracing.com/parts/EDL-2475/
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