Super Six install on 1974 Dart

[rich006]

This thread will document my project to install the "Super Six" 2-barrel setup on my 1974 Dart, originally equipped with a Holley 1945 one-barrel carburetor.

Why I'm doing this:
1. The Super Six and Carter BBD carburetor should improve the general performance of the engine. I had already wanted to do this at some point.
2. I'm doing it a bit sooner than planned because the engine is running very lean with the 1945 even though I've installed a bigger jet (64). Hopefully the Super Six will solve the mixture problem, but if not at least I'll have a better setup to work with. The 1945 is recently rebuilt and was NOS 5 years/10k miles ago, so I don't think there's much hope of improving its function. I don't want to replace it with another one, so why not make an upgrade?
3. The engine is newly rebuilt and has always had (and still has) lots of ping under load. I've done a lot of troubleshooting and I think I've narrowed the list of causes down to lean mixture. How I know the engine is running lean: several reasons but ultimately I installed an AFR sensor. It reads 15-16 under power.

The engine:
- Original to the car, 90k miles, never rebuilt until this year
- Ignition: stock electronic ignition, new plugs, nearly new wires, coil is original
- Timing: stock (0 degrees initial, about 30 degrees mechanical, all in by 3000 RPM; vacuum advance is 0 up to 6 inches, then increases to 17.5 degrees by 16 inches)
- Exhaust: stock (2" all the way back, no catalytic converter)
- Drive train: 904 transmission, 8.25" sure-grip differential with 2.71:1 gear ratio

Rebuild:
- Bored cylinders 0.030" oversize, removed about 0.100" total from block and head
- Compression ratio is now 8.9:1 static (8.0:1 "dynamic" depending how you calculate)
- Reground original camshaft to RV-10 Reverse Dual Pattern, degreed during installation
- Replaced all exhaust valves (worn stems) and one intake valve (pitted stem), replaced valve springs
- Smoothed combustion chamber valve pocket areas, smoothed and evened manifold areas (no major porting, just light cleanup)
- Rebuilt harmonic balancer
- Original crankshaft didn't need any work done
- Replaced all main and rod bearing sleeves
- Rebuilt oil pump (checked within specs in factory shop manual)
- Replaced water pump
- Kept same fuel pump, which was pretty new
- Painted everything Chrysler blue, black, or Slip Plate (exhaust manifold, pulleys, etc.)
- Adjusted valves to 0.015" intake, 0.015" exhaust per cam spec sheet
- Filled cooling system with Evans waterless coolant

Here's what the engine looked like after the rebuild. I also touched up the engine compartment with some red paint while it was empty.

The Super Six setup came complete from a junkyard 1979 Lebaron 4-door. Here it is ready to come home. Someone on slantsix.org described it as looking like it came from the bottom of a lake, and I can't disagree. The main parts I'm using are the intake manifold, linkages, brackets, and air cleaner. All of those should clean up just fine. If the carburetor is trash, so be it.

I had to go back for the piece I didn't know to get: a 3" bracket that connects the kickdown linkage to the transmission. It swings fore and aft and has a D-shaped hole in it that is different between A-bodies and F-bodies. Thanks to matv91 on slantsix.org for pointing that out. Here's that piece.

 

[rich006]

After getting everything home, the next step was to take lots of pictures and apply PB Blaster liberally while waiting to have time to tear it all apart. I'll spare you all the pictures of rusty linkages, etc.

I decided to separate the manifolds so I can use my original exhaust with the Super Six intake. That way I know I have working manifold heat, plus I'd like to reuse my clean, graphite-painted manifold that I already worked hard on. I expected to have a hard time removing the two long 5/16" bolts that hold the manifolds together, but those actually came out without too much trouble. I did spray PB every day for a week before I tried loosening them, which probably helped a lot. In the end I just put a wrench on one and tapped the wrench with a hammer until it turned. Then I did the same with the other. Here they are before coming out.

The only problem was there was a second pair of bolts that went into the same threads from the bottom. I'm not sure what they are for. One came out clean but the other's head broke off, leaving the threads in the manifold. Fortunately I don't have to solve that problem if I'm not using the manifold.

Surprisingly the nut on top of the intake manifold, that goes onto the 3/8" stud from the exhaust, was barely even wrench-tight.

 

[rich006]

By the way, big thanks to the good folks at slantsix.org for all their help so far. I've also relied on the Super Six article posted there, which has all the info you need for this job. I'm posting this thread here instead, mainly because it's so much easier to post photos here.

Once I got the manifolds separated, it was time to remove the carburetor. The first thing I thought was odd is that it has 2 bolts holding it down and two studs with nuts (is this normal?). The bolts came out fairly easily, but one of the nuts required vice grips and all my patience.

I also spent some time trying to remove the vacuum connector on the #6 runner, as well as the Charge Temperature Switch (part of EGR control). Eventually I decided to leave them in place, though I won't be using the switch. I do want to have EGR working, but as this switch works with the EGR timer system which I don't have, I could remove it. If you know how to get it out of the manifold, let me know. The hex seems to be nylon, and it was starting to break before coming loose.

 

[rich006]

Looking into the carburetor, it's not pretty. The mechanism that holds the metering rods should just lift out (right?) but it was frozen in place until I soaked it in PB.

Maybe even worse, the throttle plates were completely crusted with rust and the throttle shaft was completely frozen.

PB didn't free it up, even after several days of repeat applications. I did manage to free it by boiling the throttle plate in a solution of about 50/50 vinegar and water, but it was extra-strength "30%" vinegar. I added some Simple Green concentrate for good measure, and I put everything in a disposable aluminum turkey pan on the gas grill. After about 30 minutes of boiling, I was able to start working the throttle plate free with two pairs of pliers. After 45 minutes it was completely free and the rust was gone. I rinsed with baking soda and water to neutralize the acid.

I should have sprayed WD-40 or something to prevent the surface rust that formed within the hour. Next time...

 

[my68barracuda]

By the way, big thanks to the good folks at slantsix.org for all their help so far. I've also relied on the Super Six article posted there, which has all the info you need for this job. I'm posting this thread here instead, mainly because it's so much easier to post photos here.

Once I got the manifolds separated, it was time to remove the carburetor. The first thing I thought was odd is that it has 2 bolts holding it down and two studs with nuts (is this normal?). The bolts came out fairly easily, but one of the nuts required vice grips and all my patience.
View attachment 1715616544
I also spent some time trying to remove the vacuum connector on the #6 runner, as well as the Charge Temperature Switch (part of EGR control). Eventually I decided to leave them in place, though I won't be using the switch. I do want to have EGR working, but as this switch works with the EGR timer system which I don't have, I could remove it. If you know how to get it out of the manifold, let me know. The hex seems to be nylon, and it was starting to break before coming loose.
View attachment 1715616546

Those vacuum trees are a pot metal that break very easily. I would submerge the complete intake in Evaporust and let it set for days,,, that will clean up the inside and wick into the threads and perhaps those two fittings at #6 will be removable. Good Luck with that carb, not to discourage you, but I am not optimistic that carb will ever run right.
I run a NOS Holly 2280 for the past 8 years on my super six and it has been a fine carb.

 

[rich006]

Once the throttle shaft was free, I could feel a bit of play in it, which is a known source of vacuum leaks. As suggested by Reed on slantsix.org, I ordered a bushing kit from eBay. The kit has a reaming tool with a long shaft to align with other holes, so that the new bushing hole will be straight. However, the metal surrounding the hole is so thin that enlarging the hole would cut all the way through.

It's possible to add more metal (matv91 on slantsix.org showed how to do it), but my propane torch wouldn't get the metal hot enough to melt an aluminum brazing rod. I took the throttle body into a machine shop at my workplace, and the machinist said the wear isn't really enough to worry about. On top of that, there's a fair amount of pitting on the throttle shaft itself, so I came to realize the seal is never going to be perfect and probably wouldn't be improved by installing a new bushing. That said, it might be good enough to run OK, if the rest of the carburetor works. If...

At that point I was considering just installing the carburetor to see what happens. However, a rebuild kit and a few other needed parts will add up to over $50. And there's no telling how well it would ever work. On the other hand, I can buy a brand-new Chinese replica BBD on Amazon for $80. I'm going to try the replica.

The replica is set up for a 318, so I will need to use the choke bracket from the old carb in place of the one that will come on the replica (explained in Reed's Super Six article here).

 

[/sixchall]

Rich006, I’ve been running a Super Six set-up on my 225 for a number of years now with no problems. This is in my ‘70 Challenger so adding a little performance to the six was a good idea to me. Thanks, Al

 

[/sixchall]

Rich006, I forgot this info, using steel tube headers creates a lot of Underhood heat. So the heat goes straight up under the carb creating some fuel boiling and vapor lock on triple digit days here in SoCal. I decided to make a carb heat shield out of 1/8” T6 alum. So that it fits under the carb and covers most of the manifold runners toward the valve cover. Had it polished and will put it on as soon as the spirit moves me. Thanks and good luck, Al

 

[RustyRatRod]

Once the throttle shaft was free, I could feel a bit of play in it, which is a known source of vacuum leaks. As suggested by Reed on slantsix.org, I ordered a bushing kit from eBay. The kit has a reaming tool with a long shaft to align with other holes, so that the new bushing hole will be straight. However, the metal surrounding the hole is so thin that enlarging the hole would cut all the way through.
View attachment 1715616708
It's possible to add more metal (matv91 on slantsix.org showed how to do it), but my propane torch wouldn't get the metal hot enough to melt an aluminum brazing rod. I took the throttle body into a machine shop at my workplace, and the machinist said the wear isn't really enough to worry about. On top of that, there's a fair amount of pitting on the throttle shaft itself, so I came to realize the seal is never going to be perfect and probably wouldn't be improved by installing a new bushing. That said, it might be good enough to run OK, if the rest of the carburetor works. If...

At that point I was considering just installing the carburetor to see what happens. However, a rebuild kit and a few other needed parts will add up to over $50. And there's no telling how well it would ever work. On the other hand, I can buy a brand-new Chinese replica BBD on Amazon for $80. I'm going to try the replica.

The replica is set up for a 318, so I will need to use the choke bracket from the old carb in place of the one that will come on the replica (explained in Reed's Super Six article here).
View attachment 1715616715

Rich, IMO, everybody makes a WAY bigger deal about throttle shaft wear than what really matters. Think of it this way. The incoming air and fuel charge is going to take the path of least resistance into the engine. That's through the air cleaner and right down the carburetor throat. It's been my observation over the years that you have to have a lot of wear in the throttle shaft and bores to really affect how the engine runs and most of the time you tune it out anyway when you adjust the air mixture screws.

 

[volaredon]

Once the throttle shaft was free, I could feel a bit of play in it, which is a known source of vacuum leaks. As suggested by Reed on slantsix.org, I ordered a bushing kit from eBay. The kit has a reaming tool with a long shaft to align with other holes, so that the new bushing hole will be straight. However, the metal surrounding the hole is so thin that enlarging the hole would cut all the way through.
View attachment 1715616708
It's possible to add more metal (matv91 on slantsix.org showed how to do it), but my propane torch wouldn't get the metal hot enough to melt an aluminum brazing rod. I took the throttle body into a machine shop at my workplace, and the machinist said the wear isn't really enough to worry about. On top of that, there's a fair amount of pitting on the throttle shaft itself, so I came to realize the seal is never going to be perfect and probably wouldn't be improved by installing a new bushing. That said, it might be good enough to run OK, if the rest of the carburetor works. If...

At that point I was considering just installing the carburetor to see what happens. However, a rebuild kit and a few other needed parts will add up to over $50. And there's no telling how well it would ever work. On the other hand, I can buy a brand-new Chinese replica BBD on Amazon for $80. I'm going to try the replica.

The replica is set up for a 318, so I will need to use the choke bracket from the old carb in place of the one that will come on the replica (explained in Reed's Super Six article here).
View attachment 1715616715

no a propane "coffee warmer" torch hears too slowly to do any good,,,, the rest of the casting will absorb the heat before the spot you want hot gets there....
and on the choke adapter piece.... I found a carb rebuilder out of Chicago via Ebay, that had several of those super 6 choke links available...... I bought 3
one for the kid's truck
one for my truck
one for my spare/backup BBD..... of which I have 3 to cherry pick from, to hopefully get 2 "good" ones from.

 

[volaredon]

Rich, IMO, everybody makes a WAY bigger deal about throttle shaft wear than what really matters. Think of it this way. The incoming air and fuel charge is going to take the path of least resistance into the engine. That's through the air cleaner and right down the carburetor throat. It's been my observation over the years that you have to have a lot of wear in the throttle shaft and bores to really affect how the engine runs and most of the time you tune it out anyway when you adjust the air mixture screws.

I have a slant spec Holley 1945 1 barrel, that is WAY loose..... that engine would barely run til I swapped that carb out. the one that was on my Volare originally was just as bad but back then I had a buddy that worked maintenance in a factory that could fix stuff like that all day long in the company's tool room/machine shop..... said company has since closed their doors, my buddy now works maintenance at a state park campground in Indiana, no access there to same kinds of machines.

 

[RustyRatRod]

I have a slant spec Holley 1945 1 barrel, that is WAY loose..... that engine would barely run til I swapped that carb out. the one that was on my Volare originally was just as bad but back then I had a buddy that worked maintenance in a factory that could fix stuff like that all day long in the company's tool room/machine shop..... said company has since closed their doors, my buddy now works maintenance at a state park campground in Indiana, no access there to same kinds of machines.

Yes, the later ones were much worse as the material quality went way down. Also too, people tend to pue way heavy throttle return springs on as well. It doesn't take much.

 

[rich006]

The new carburetor arrived yesterday. It looks to be well-made from the outside (not the important part, I know). It not surprisingly has slightly different vacuum ports from the one that came with the manifold. The two matching large nipples on the throttle body seem to both lead directly into the intake manifold. I assume one is the charcoal canister purge, and the other gets capped. The smaller one in the throttle body looks like it's probably the distributor vacuum advance. The small one next to the choke pulloff hose is probably to control the air cleaner inlet heat door. The one coming out the side of the bowl below the choke bracket might be for EGR control, and the large one above the bowl is clearly the bowl vent (to charcoal canister). The one between the idle mixture screws is PCV.

Speaking of the choke bracket, it looks like I might not need to replace it. It seems to have the hole oriented more or less the same as the junkyard one.

 

[volaredon]

The one that is under the choke link about 1/2 way up the side is usually the vac advance on a BBD. It's routed internally to where it has to draw ported vacuum from

 

[Bugman]

The one that is under the choke link about 1/2 way up the side is usually the vac advance on a BBD. It's routed internally to where it has to draw ported vacuum from

 

[volaredon]

The port you want to run the distributor vacuum advance from says "to distributor OSAC valve" run a vac line directly between the two, factory did it this way for years without the OSAC valve.

 

[rich006]

I started cleaning up the intake manifold and air cleaner to prep for painting. The air cleaner is pretty rough. The wire wheel went right through the lid in several places. Also, there's a large rusty port on the bottom that I can't identify.

 

[my68barracuda]

I started cleaning up the intake manifold and air cleaner to prep for painting. The air cleaner is pretty rough. The wire wheel went right through the lid in several places. Also, there's a large rusty port on the bottom that I can't identify.
View attachment 1715618279 View attachment 1715618280

To save that air cleaner housing, I would soak it in a liquid rust remover to get all of the rust out. Then use fiber glass cloth and fiberglass resin to patch the rusted through spots. The patches will show so put them on the inside. If you have not done this before there are how to video’s on you tube. Then use a good grade of body filler over the outside surface where the patches and the pitted surfaces are to bring them back to smooth. You will be putting on a thin layer so get a filler intended for final smoothing. A lot of effort but doable. Or continue the search for a better air cleaner housing.

 

[RustyRatRod]

To save that air cleaner housing, I would soak it in a liquid rust remover to get all of the rust out. Then use fiber glass tape and fiberglass resin to patch the rusted through spots. The patches will show so put them on the inside. If you have not done this before there are how to video’s on you tube. Then use a good grade of body filler over the outside surface where the patches and the pitted surfaces are to bring them back to smooth. A lot of effort but doable. Or continue the search for a better air cleaner housing.

Yup. DO it like John says ^^^^^^ and when you're done, you'll never know it!

 

[rich006]

use fiber glass cloth and fiberglass resin to patch the rusted through spots

I was already thinking of doing that. I've done it on truck wheel arches, with good results. On the outside, I used the West Marine 410 fairing filler. Thanks for the encouragement!

I guess while I'm at it, I can cut off that port on the air cleaner base and seal it up. Is it intended to provide clean air to the crankcase? I assume it was capped when installed on the original car, which would explain why it's so rusty.

View attachment 1715618229

Wow, I had it all wrong (not the first or last time!). The smaller port in the throttle body is clearly intended for the heated air inlet system. It leads directly to the groove in the base, same as the one in the manual but shifted over to make room for the 2nd large port. I assume the 2 large ports are to give you a choice of PCV routing direction.

 

[rich006]

I applied some fiberglas with epoxy resin to the inside of the air cleaner lid. At first the glass mat didn't want to follow the contours of the lid, so I tried with smaller pieces of mat and that worked better. I forgot how fast the epoxy sets up if you have a decent amount of it in a cup. The more you have, the hotter it gets and the quicker it sets. The small amounts on the lid took several hours to cure. I also patched the hole in the bottom of the air cleaner base, and I went ahead and patched the hole for the OSAC too.

Before applying epoxy, I wire-wheeled the areas and wiped with acetone.

 

[rich006]

Do you know where I can find a plug to fill the hole where the air inlet temperature sensor goes into the #6 runner on the manifold? As I was prepping to paint, I decided to remove that sensor. I thought it was starting to break free but it was just breaking. I had to chisel and punch out the plastic (nylon?) threads that were left inside. I can get a new sensor from RockAuto for $14 but I'd rather just plug the hole. It looks to be 5/8" with about 20 threads per inch.

 

[rich006]

What material works well to replace the air cleaner lid seal? The old one appears to be a 3/8" x 3/8" strip of foam. I found a replacement at Classic Industries, but it looks like something you could get at any hardware store.

 

[RustyRatRod]

Do you know where I can find a plug to fill the hole where the air inlet temperature sensor goes into the #6 runner on the manifold? As I was prepping to paint, I decided to remove that sensor. I thought it was starting to break free but it was just breaking. I had to chisel and punch out the plastic (nylon?) threads that were left inside. I can get a new sensor from RockAuto for $14 but I'd rather just plug the hole. It looks to be 5/8" with about 20 threads per inch.

View attachment 1715619239 View attachment 1715619240

Purt near anywhere. It's just a 3/8 pipe plug I believe.

 

[rich006]

Purt near anywhere. It's just a 3/8 pipe plug I believe.

I didn't know pipe threads are measured according to the inside diameter of the pipe (of course it makes sense if you care about the flow through the pipe!). I found a chart showing that if the OD of the threads is 0.540" with 18 threads per inch, then it's NPT 1/4", which is available just about everywhere as you said. [EDIT: it's actually NPT 3/8".]