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DualJet???

Discussion in 'The Garage' started by ntsqd, Nov 4, 2006.

  1. ntsqd

    ntsqd 1/2 ton status

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    Searched, found a description that matches my friend's inquiery. Can anyone fill in more of the gaps?

    "I saw something interesting/weird at the junkyard yesterday. Since I
    got my carb rebuilt by a performance shop, I've been on the look out for an
    old Rochester Quadra Jet as that is what he recommended as the best off
    road carb. Anyway, apparently this is a highly sought after item at the
    local Pull A Part yard as they seem to be missing off of all the cars
    that originally came with them. Yesterday, I saw a carb just laying on
    the intake and the intake had the tell tale small primary holes/large
    secondary holes. I thought I had really lucked out but when I picked up
    the carb, it really was strange. It had butterfly valves and the normal
    hardware on the primary side, but nothing on the secondary side. No
    butterfly valves, shaft, linkage, etc, absolutely nothing. In fact, on
    top of the carb, the secondary side had a cover plate with the logo
    Rochester Dual Jet. Obviously this was some sort of weird
    configuration, but I'd never heard of it before. Can anyone tell me what GM was thinking with this configuration? Was it some sort of low emissions
    version? Higher mileage? It looked like it could have been turned into
    a normal one if it was machined for the shaft and the rest of the parts
    were added."
     
  2. RaisedK5

    RaisedK5 1/2 ton status

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    Its a rochester 2 bbl carb

    1 bbl = mono Jet
    2bbl = Dual Jet
    4bbl= Quadra Jet
     
  3. ntsqd

    ntsqd 1/2 ton status

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    That part we knew. What I'm interested in is why were they made and what did they come on?
     
  4. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    I've seen em on a few oddball marine packages over the years... And I do mean oddball...
     
  5. 3 on the tree

    3 on the tree 1/2 ton status

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    Is the carb opening on top rectangular, rather than round? I have had 3 or 4 of these on GM 2.8 V6 front wheel drive cars. Staged 2 barrel, works like a Q Jet, only 1 primary and 1 secondary bore.
     
  6. ntsqd

    ntsqd 1/2 ton status

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    From his description, no. Sounds like a normal 4 bbl air cleaner can would fit on it.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Yes, GM made the Q-jets with the secondaries essentially cast shut.

    I assume it was because it simplified/cheapened parts procurement...same intake, throttle linkage, carb internals, etc. as anything with a Q-jet. Probably slightly better on economy and mileage than a standard quadrajet overall, just because there was no way to dump as much gas in. Obviously not used on anything that made much power.

    I'd be curious to find out if it had the big or small primary venturis though...
     
  8. ntsqd

    ntsqd 1/2 ton status

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    Since it was in a JY I'd be surprised if he bought it. So unfortunately that may remain a mystery. It's up in the wet side of Washington state. If there's someone interested enough to track it down & buy it, I can find out where it is exactly.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Nah, it's worth nothing, just curious if someone heads back and can look at it. :)
     
  10. u2slow

    u2slow 1/2 ton status

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    I think I saw one of those on my sister-inlaw's '81ish Olds Cutlass... 267ci SBC if I remember correctly. :rolleyes:
     
  11. fatbob

    fatbob 1/2 ton status

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    I've seen a lot of them on '60's & '70's era cars and trucks. Dont forget we had that gas shortage back in the '70's, and in the '60's we had engines with less than 300ci. like the good ole 283ci, so they didnt need carbs with much more cfm's than the two barreled carbs provided.
    And I dont think its a down sized quadrajet, but more likely a quadrajet is an upsized dualjet.
    anyways here's a couple pics of one
    http://i100.photobucket.com/albums/m5/fatbob2/HPIM0030.jpg
    [​IMG]
    http://i100.photobucket.com/albums/m5/fatbob2/HPIM0029.jpg
    [​IMG]
    http://i100.photobucket.com/albums/m5/fatbob2/HPIM0028.jpg
    [​IMG]
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    From his description, that is NOT what was seen.

    I know exactly what is being are talked about, it IS a Quadrajet with the secondaries cast shut.

    I see reference to a "Quadrajet 2MC" online, but I can't find any photos of what is being talked about, even on ebay.
     
  13. fatbob

    fatbob 1/2 ton status

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    Going by his description with, " with the logo
    Rochester Dual Jet, " I'm just betting it's a different version of the pics I posted. I have seen those before but don't have a pic to post.
    I believe the "dual" & "quadra" part of the name refers to the number of jets. There is even a monojet out there:eek1: but that had to really suck for performance.
     
  14. u2slow

    u2slow 1/2 ton status

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    I've seen the the 2MC before.... I think it was the 2bbl that bolts right onto a 4bbl intake.

    EDIT: Let's not forget about the Vari-Jet too. :D
     
  15. blazin_blazer

    blazin_blazer 1/2 ton status

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    i know what your talking about , i have 1 put back some where in my shop just because its an oddity. as far as quadrajets go you don't want the rochester quad, but rather the quadrajet made by carter they are the best 1's, most people arond here call the rochester a quadrajunk. the carters are different and you will know when you find 1 it will say quadrajet by carter on the side, instead of rochester quadrajet. they are off of the muscle car era tho,thus making them even that much harder to find. you pay shipping and i will send you a rochester quadrajet(it may need a rebuild kit tho)it was running tho when we pulled the engine and put it on the shelf. i'll never use it or the other 2 or 3 i have,but i will let you have one if you pay to ship ,i've rounded up 2 complete carter quadrajetand another thats in pieces in a box, plus my favorite a carter afb competition series. its a good carb, but it is close to being the same as edelbrocks carbs, takes their rebuild kit but they don't make them anymore since carter went out of business and edelbrock bought their design and tweaked it.made smaller primaries and secondaries and smaller fuel passages inside the carb from fuel bowl to the venturies then started making them under their name. basically made it a reliable gas sipper out of a competition series carb, not as good after you get over the 300-350 hp engine, where as the carter afb will feed upwaeds of 600hp.
     
  16. blazin_blazer

    blazin_blazer 1/2 ton status

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    ntsqd did you read my post above, do you need it that bad? let me know in this thread and i will send you contact info!
     
  17. 1977k5

    1977k5 3/4 ton status Vendor

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    My truck came stock with a Carter built Q-jet, so I don't really buy that muscle car era thing. I think most people call the Rochester made ones junk because they don't know what they are talking about. I think Carter just built some carbs for Rochester because Rochester couldn't keep up with demand. There shouldn't be any inherent difference between a Rochester and Carter Q-jet (although there were like 100 different versions of the Q-jet).
     
  18. OrangeCrushK10

    OrangeCrushK10 1/2 ton status

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    Sounds kinda like what i had on a 350 I got out of a '74 Nova.

    That carb was the biggest hunk of junk in the galaxy.
     
  19. ntsqd

    ntsqd 1/2 ton status

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    I don't need one at all. My friend found one of these carbs in the junk yard and was curious about it.

    If someone has one, dyeager would be interested in knowing what the venturi size is.
     
  20. blazin_blazer

    blazin_blazer 1/2 ton status

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    i was talking about sending you 1 of my rochester quadrajets-4 barrel , you said they where hard to find them and i have alot of them, i'm keeping all the carter made one's, up to about 74 sounds about right. but rochester never put a carb on the musle cars, carter built them original(1st) and they couldn't keep up with gm's demand because they made other carbs, rochester got the nod to fill in ...when carter's contract was up with gm they quit making them in mid 70's. its all in my book about gm's history, and 1 of my BBC's(396 turned 427) is a '66 and i got it stock out of an el camino my grandfather bought new, had the carter on it. i said most people call them quadrajunk. i think they are a very good carb for off roading with their center hung floats. i've inspected a rochester upside the carter....the carter had better looking casting, not as much flashing as the rochester, i was going to send you 1 off of a '78 c-20 350....i like to find them off the big caddies or big blocks they have more cfm!! i'll try and find the dual jet and measure it, you want just the venturies or the bore size?
     
    Last edited: Nov 7, 2006

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