Holley 6709 double pumper 750 carb info

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2x4-451Demon71

2x4-451Demon71

Some millennials are cool.
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So I'm trying to find out information on this special 6709 carb holley made. I have actually have two of them! And I would like to incorporate these bad boys into my build.. I am a young guy but I'm cleaver enough to have some careful fun! And constructive criticism welcom as long as I don't half to read through 100 pages of bickering haha but that beaing said this place is my mopar Bible and I wouldn't even have bought this car if it wasn't for this place! Thank you everybody ! I guess this makes me a long time listener first time caller haha..

So I own a cleanish.. at least 97 % rust free all Alaskan 71 dodge demon! I'm building a 451 low deck stroker! I've got a 73 400 lodeck block, 440 sorce heads and the 10 degree lockers with there unbalanced stroker kit, a weiand dual quad tunnel ram I also have an 8 3/4 rear with a 18 spline 4 speed and sub frame connectors. I have not chosen a cam yet but I was aiming towards the solid or solid roller .528 ish lift cam.
I do have 1 3/4 tti shorty headers.. because I love the power steering.. but I just thought I would through the combo out there I wanna be able to race for sure! But I Olney plan to drive it on sunny, well not raining days due to the amassingness sticking out of the hood and alaska summers kinda suck some years... but I'm would like to see if these 6709 holley carbs are usable for my build! Thanks!

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Subscribed! :popcorn: Sounds like a great car. I love Demons. Wish I could help on the carb. info. Keep us posted on your build and good luck!
 
I’d pass on using those carbs. They are spread bore emissions carbs. You’ll have more time and money in them than they are worth.
 
holley labled those carbs as an emmission performance carb. they are on a 4150 square bore bolt pattern but are more like a 4165 spread bore carb. they have a 1 9/16 primary throttle blade and a 1 3/4 secondary. they also have the spread bore reverse idle system with different fuel bowls, metering blocks than a standard 4150 carb has. i ran that carb on some stock 340 dusters and road runner back in the day. was a great carb on those stock motors. a plain ol list 4779 750 double pumper is the better carb for what you have in mind.
 
Ooo! OK that makes more sense! So I wanted to use these carbs because I thought they would behave like a spread boar with the smaller primary sand give me better lo end torque, with enough cfm flow for my big block. So bad news is I allready bought the special rebuild kits they need.. so how dose the reverse idler circuit work? Is it something I can adapt to my build? And I don't mind tinkering... actually I kind of love it hahaah
 
Use the Holleys as boat anchors & use Carter/Edel AFBs.
 
Those spreadbore type carburetors are a tuning nightmare if you are going to try & run them on the tunnel ram you have pictured. You would be better off running the Edelbrock or Holley square bores.
 
Bewy said:
Use the Holleys as boat anchors & use Carter/Edel AFBs.
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I don't have the time, 30+ years trying to get a Carter tuned.
Holley's are much more tunable and forgiving than an Edelcarter. imo
 
So some of the questions I'm thinking about these weird carbs are, 1. can these carbs have that backfire check ball protection installed? 2. I've herd they don't flow what they should. is that a good thing? cause together their possibly to big for my 451... 3. I saw something about these in a dual quad circumstance, what kind of power valve arrangement and jetting would these weird things run if they were on a tunnel ran? Or would I be the first person to try these puppy's as a dual quad
 
some-millennials-r- said:
So some of the questions I'm thinking about these weird carbs are, 1. can these carbs have that backfire check ball protection installed? 2. I've herd they don't flow what they should. is that a good thing? cause together their possibly to big for my 451... 3. I saw something about these in a dual quad circumstance, what kind of power valve arrangement and jetting would these weird things run if they were on a tunnel ran? Or would I be the first person to try these puppy's as a dual quad
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1. Power valve protection is JUNK. You don’t need it.

2. Flow is a piss poor way to rate a carb. Stop worrying about it.

3. The only way to know this is to take them apart and pin them. Then you can decide what the tune up should be.

Im getting the feeling you have a hard on to use these garbage carbs. I’m old enough that I no longer need to fix the unfixable or to try and shove a Diamond up a goats ***. Or buff a turd.

Youth has a strange way of making you think you can turn chicken **** into chicken salad. Age makes you know it’s still chicken ****.

I‘m not trying to tall you out of or in to any carb(s). I’m telling you that you have a ton of study to do before you spend another red cent on anything.
 
If a carb that uses a rubber diaphragm that is subject to engine backfire was well designed, it would have had backfire protection from day one.....
 
Yaa.. I am truly a snot nose kid lol I'm 27.. but at least I'm doing something, I mean I'm takeing care of my parents and my nephew and I have a muscle car lol.. but all my friends are complete millennial's and are total dummies hahah but yes I have plenty of time to tinker, actually I have a hole cold a$$ winter to tinker lol so I don't mind but the way I think about it is might as well try. worse case scenario they don't work, and Thanks!! As stated above, I am a snot nose kid, but I love reading about this stuff, I just don't know where to find more info about these carbs, lol
 
So I think I read that 90s holley carbs had blow out protection, but every carb be for that did not.. that and these are 1971 carbs I think..
 
I am pretty sure that blow out protection came MANY years the 4 bbl intro in 1957. I would think a first year engineering student would have picked up on that failing. Likewise the acc pump transfer port that had a tendency to leak. Eventually a brass tube with an o ring each end was fitted to solve 'the problem'.
Carters were perfectly designed from day one, didn't need upgrades...
 
some-millennials-r- said:
So I'm trying to find out information on this special 6709 carb holley made. I have actually have two of them! And I would like to incorporate these bad boys into my build.. I am a young guy but I'm cleaver enough to have some careful fun! And constructive criticism welcom as long as I don't half to read through 100 pages of bickering haha but that beaing said this place is my mopar Bible and I wouldn't even have bought this car if it wasn't for this place! Thank you everybody ! I guess this makes me a long time listener first time caller haha..

So I own a cleanish.. at least 97 % rust free all Alaskan 71 dodge demon! I'm building a 451 low deck stroker! I've got a 73 400 lodeck block, 440 sorce heads and the 10 degree lockers with there unbalanced stroker kit, a weiand dual quad tunnel ram I also have an 8 3/4 rear with a 18 spline 4 speed and sub frame connectors. I have not chosen a cam yet but I was aiming towards the solid or solid roller .528 ish lift cam.
I do have 1 3/4 tti shorty headers.. because I love the power steering.. but I just thought I would through the combo out there I wanna be able to race for sure! But I Olney plan to drive it on sunny, well not raining days due to the amassingness sticking out of the hood and alaska summers kinda suck some years... but I'm would like to see if these 6709 holley carbs are usable for my build! Thanks!

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Nothing to do with your question, but just a friendly tip. In my lifetime, I've had to cut two things off another person. One was a ring and one was a watch. Both because said person grounded themselves to the positive post of the battery while working on a car. The ring was in high school auto shop. It cooked his finger to the bone. I had to cut his class ring off with a pair of dykes, because the skin around it was swollen all up and it would not slide off. Very painful. The watch did the same thing but on the guy's wrist. It was worse in that was stuck badly to his wrist. We wanted to leave it for the paramedics, but he was insistent we cut it off, so we did. It took a LOT of skin with it. So word to the wise. REMOVE metal play pretties around cars......or cease wearing them at all.
 
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Thanks! I do appreciate the heads up! when I work on electronics I usually ground myself to them for static safety to the electronics but now I'm working on bigger stuff and I allways take my watch off, and I don't have any piercing or rings or any of that stuff.
So my dad was one of the guys who worked on the electronics for the halon gas fire suppression system back at Prudhoe bay rig back in the early 80s and he actually later designed all the guns rockes and brought the crashes back for flight simulator in the 90s and 2000s with some dlc stuff witch is super cool lol here's some pics!

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Bewy said:
If a carb that uses a rubber diaphragm that is subject to engine backfire was well designed, it would have had backfire protection from day one.....
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That’s not true. ”Backfire protection” came about like most things. Guys have no clue what’s happening and they blame the power valve or a backfire for their tuning issues.

FWIW, Holley KNEW it had an internal leak problem and they covered it up. If you bought a Trick Kit rebuild kit you got the fix. The problem was (and still is) there are no instructions for it.

Just another reason to NOT buy Holley.
 
Rat Bastid said:
That’s not true. ”Backfire protection” came about like most things. Guys have no clue what’s happening and they blame the power valve or a backfire for their tuning issues.

FWIW, Holley KNEW it had an internal leak problem and they covered it up. If you bought a Trick Kit rebuild kit you got the fix. The problem was (and still is) there are no instructions for it.

Just another reason to NOT buy Holley.
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More delicious information! Thanks! Now I'm gonna go read about holley leaks and trick kit stuff
 
RB,
Engines were backfiring in the 1950s when Holleys were designed & sold.....Didn't just start happening many years later....when H brought out a fix. It was an engineering failure, & a very simple one, that the carbs did not have BF protection from day one.
 
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