Six Pack question

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LD-Ordie

LD-Ordie

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I have a 68 Dart with a stroker 340. Exploring the idea of adding a Six Pack to it. Currently have a 750 Holley. Getting 13 MPG around town driving normal using 3.21 gears and a 4 speed. Does the center carb on a Six Pack get better, worst or the same as a double pumper? Also have a 55 chevy with a Tri-Power, 3 2G Rochesters, and a 55 Ford with 3 Holleys. I gained 5 mpg on each going from a Holley 650.

Do the Holley's secondary carbs on a Six Pack maintain the idle circuits? How well do the outboard carbs seal? My other systems seal 99% and act as fuel dumpers only when WFO. Super easy to tune. Just trying to get educated here.

Is there a hood clearance issue using a stock hood?

Appreciate any advice offered
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You can improve fuel mileage with a six pack over your current setup if you are driving very modestly. But if you're getting into the outboard carburetors all bets are off and fuel mileage will drop! LOL. Outboard carburetors are involved in the idle circuit. The carburetor seal nicely when they're in good working order, old carburetors and carburetors that have been over tightened to the manifold can warp causing problems but it usually shows up in the form of sticky butterflies and vacuum leaks but I've never experienced a problem myself. I ran a fairly large hydraulic camshaft causing me the need to increase primary jetting in the center carb which did decrease fuel mileage.
 
Holy moly Batman!

LD-Ordie said:
Does the center carb on a Six Pack get better, worst or the same as a double pumper?
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Double pumped or not, It’s the same size.
Also have a 55 chevy with a Tri-Power, 3 2G Rochesters, and a 55 Ford with 3 Holleys. I gained 5 mpg on each going from a Holley 650.
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Thats because it is breathing easier.
Do the Holley's secondary carbs on a Six Pack maintain the idle circuits?
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Yes
How well do the outboard carbs seal?
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As well as any other carb.
Is there a hood clearance issue using a stock hood?
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I’m not 100% in this.
Appreciate any advice offered View attachment 1715927047
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Get an 02 sensor and runs your current carb. Your mileage is on the slightly on the low side.
Get ride of that intake, it’s a choker. Look at a Edelbrock RPM as the only dual plane up to task on a stroker and have it ported. As cast, it’s still choking the engine.

IF you already have the 6 pack great! Have the ported as well. If you don’t have the intake, best of luck finding one! LMAO!!!! Edelbrock hasn’t made any new ones in a long time and there selling around the 1,000 mark.
 
I run 391 rear end and a 4-speed and get around 13 miles to the gallon in mixed driving. I'm sure I could get 16 MPG On the highway if I didn't go over 65 and and just cruised.
 
As far as Clarence goes it all fits under my stock 70 340 Swinger Hood assembly with about a half an inch to spare!

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My opinion only:
You have to want a Sixpack for eyewash only, and be willing to spend for it on that basis only. It will probably make a little more power than your 750, and it might, MIGHT, get better gas mileage, as stated above, only if you keep your foot out of it.
But it would have to give you thirty mpg for ten thousand miles a year to pay for itself, and that ain't gonna happen!
For reference, I love my Sixpack big block, and I have another new manifold, but the cost of carbs vs performance increase over my 850dp is negligible, and I won't spend for Sixpack carbs for eyewash.
 
33IMP said:
My opinion only:
You have to want a Sixpack for eyewash only, and be willing to spend for it on that basis only. It will probably make a little more power than your 750, and it might, MIGHT, get better gas mileage, as stated above, only if you keep your foot out of it.
But it would have to give you thirty mpg for ten thousand miles a year to pay for itself, and that ain't gonna happen!
For reference, I love my Sixpack big block, and I have another new manifold, but the cost of carbs vs performance increase over my 850dp is negligible, and I won't spend for Sixpack carbs for eyewash.
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I hear people say things like this and I respect your opinion but I feel there's a lot more than just eye washed involved and running a small block six pack. Number one being the rarity and the complexity to keep it running in top shape is definitely a level above throwing a four barrel on a high-rise, secondly a six pack properly tuned will run with any combo to around 500 horsepower where in my opinion it begins to reach some limitations. Yes I would never pick it for Max output at the track but I run a street car and the overall presentation means a lot to me. But if your budgeting performance per dollar by all means a six packs small block is the most amount of money for the least amount of upgrade HP that you could make. But then again I don't shop at Walmart either lol
 
You say never installed ?does that mean the carburetors are brand new? that looks like an original factory TA manifold to me. I'd like to see more pics. Nevertheless congratulations you've joined a small group of badass small block mopars
 
Carbs appear used, intake has never been installed, My first venture into the Mopar multiple carbs. My other systems were all pieced together from swap meets . Each are very reliable and daily drivers. I'm retired and have time to tinker......
 
Sounds awesome, it is a little patience in love relationship it's definitely a learning curve and would never suggest it for someone's daily driver just because they do like attention. Never seems to be a problem at full throttle working out the idle circuit always seems to be the most challenging for me. I'm pretty dialed in now. It looks like an original ta manifold to me so depending on your HP goal I don't know if I'd be jumping on it with a port job right off the bat. As rumble said that's $1,000 manifold as is.
 
K.O. SWINGER said:
You say never installed ?does that mean the carburetors are brand new? that looks like an original factory TA manifold to me. I'd like to see more pics. Nevertheless congratulations you've joined a small group of badass small block mopars
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The intake is the very last style offered by Mopar Performance. No way no how a T/A manifold. The last ones were made by God knows who and can be spotted easy by the 2 machined area's I have outlined.

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340six said:
The intake is the very last style offered by Mopar Performance. No way no how a T/A manifold. The last ones were made by God knows who and can be spotted easy by the 2 machined area's I have outlined.

View attachment 1715927087
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Good catch I stand corrected I always look for the lettering or lack of on the thermostat crossover passage not seeing any I assumed it was an Edelbrock factory manifold my bad (port away)
 
I have the same matching marks on mine.

The six pack is something you want to do, I’ve always said that. Back in the day….. LOL …..
The only other dual plane intake worth looking at was the LD-340 on making any power. The single plane is really a race intake. Not in the same category.

MoPar suggests the 6 pack because it’s there intake. Not the competitions. Even though Edelbrock did cast both and both were offered by MoPar at one time. But once that intakes production ceased……

The 6 packs claim to fame beyond its looks is it’s flexability. Seeing the dyno tests through out the years, as long as that set up is well dialed in, it stands side by side with standard dual plane 4bbl intakes.

It’s just a lot of money for no gain over a good 4bbl carb and intake.
 
K.O. SWINGER said:
Good catch I stand corrected I always look for the lettering or lack of on the thermostat crossover passage not seeing any I assumed it was an Edelbrock factory manifold my bad (port away)
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That's what I did with the same type. I sold a real or over the counter one that had value to someone else. And got one to modify. I know I posted these pics before but I cut the machined area's into a a rounded shape. I did ruin a real one before, but refrained for doing so again.

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intake2.JPG.jpg
 
340six said:
That's what I did with the same type. I sold a real or over the counter one that had value to someone else. And got one to modify. I know I posted these pics before but I cut the machined area's into a a rounded shape. I did ruin a real one before, but refrained for doing so again.

View attachment 1715927088

View attachment 1715927089
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That's funny I thought about doing the same thing because mine is an authentic ta I wanted to do some modifications but for now it remains stock who knows what the future holds. By the way your manifold looks righteous very nice.
 
I see fuel economy issues as a desire to swap. What has been done to the 750 metering to get the cruise levels correct? If the only thing does has been to change jets, that only scratches the surface.

A 6 pack flows the same air as a true 950 4 barrel carb IIRC. Never seen a 6 pack make the same power as a well tuned 950cfm 4 barrel, rpm air gap or victor.
 
crackedback said:
I see fuel economy issues as a desire to swap. What has been done to the 750 metering to get the cruise levels correct? If the only thing does has been to change jets, that only scratches the surface.

A 6 pack flows the same air as a true 950 4 barrel carb IIRC. Never seen a 6 pack make the same power as a well tuned 950cfm 4 barrel, rpm air gap or victor.
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that's like walking up to a Harley and saying wow you could get another 10 horsepower out of that if you put a different exhaust pipe on it. Okay LOL
 
crackedback said:
A 6 pack flows the same air as a true 950 4 barrel carb IIRC. Never seen a 6 pack make the same power as a well tuned 950cfm 4 barrel, rpm air gap or victor.
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Victor = race intake, totally different category.
RPM = IMO, bar none the best NEW dual plane intake.

Now if it were only available back in the day. The next best thing IMO is a LD340.

Mathematically, the 6 pack converts to 955 cfm. I’m not sure if that size carb was available back then. I don’t think so. What is the primary sizes of a 950? Larger than a 6 pack or 750? I’d think so but don’t know how things work with venturi sizes and butterfly sizes on all the various Holley carbs.

The one thing I know for sure is there were no trick carbs back then that could even hold a candle to todays offerings. Today, there’s some really nice trick pieces out there.
 
K.O. SWINGER said:
I hear people say things like this and I respect your opinion but I feel there's a lot more than just eye washed involved and running a small block six pack. Number one being the rarity and the complexity to keep it running in top shape is definitely a level above throwing a four barrel on a high-rise, secondly a six pack properly tuned will run with any combo to around 500 horsepower where in my opinion it begins to reach some limitations. Yes I would never pick it for Max output at the track but I run a street car and the overall presentation means a lot to me. But if your budgeting performance per dollar by all means a six packs small block is the most amount of money for the least amount of upgrade HP that you could make. But then again I don't shop at Walmart either lol
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I have had an excellent running 440 Sixpack, and I agree, they can run VERY well, and be a lot of fun. The "bawaaaah" when the secondaries open is legendary. And if I could get even a set of core carbs for under a grand (more than a dominator or a custom 1000cfm 4150), I would cobble up something to use my new manifold.
I just have trouble justifying the expense. What is a small block Sixpack now with rebuilt carbs, an intake, aircleaner, a/c element, linkage and fuel lines now? $5000? More?
 
K.O. SWINGER said:
that's like walking up to a Harley and saying wow you could get another 10 horsepower out of that if you put a different exhaust pipe on it. Okay LOL
Click to expand...

Not sure what the point is here. it certainly isn't 10HP... One I was involved with was on the measure of 35HP. Eye candy 6 pack wins, performance not so much.

Fuel economy was an issue. That has zero to do with the set up being a six pack or a 750-950 carb... it's the same as always... TUNE UP
 
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