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4x2 set-up for SBC

Discussion in 'The Hokey Ass Message Board' started by lucky23, Apr 29, 2012.

  1. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Just wanna see if anyone has any experience running the Offy 4x2 sbc intake with Rochester 2g carbs on 327 sbc. Looking to swap to it from my Edelbrock 3x2 set up. Is it good for everyday street use? Would planning on running none progressive linkage.


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  2. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Anyone?


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  3. Lurk king
    Joined: Dec 12, 2011
    Posts: 197

    Lurk king
    Member

    I ran one for a very short time on my 283. My experience was very mixed,
    When I first got it running it was amazing. The throttle response was so crisp and it ran great. Not a lot if torque especially on a 283 but I run very steep gears (4.62's + 5spd. + light car +lots of RPM= lots of fun.)

    The reason I switched back to my tried and true 3x2 setup was I spent a ton of time setting up the linkage(eelco) on the bench and getting all the carbs tuned and timed perfectly. Witch was reflected in how well it ran. But then I did a stupid thing and tried to put a double return spring on in a hurry to go drag racing and and it put to much stress on one side of the linkage and they all got out of sync in a bad way. Long story short After i pulled out all my hair trying to get the linkage tuned again, i pulled it off with plans of building a new linkage more like the man-a-fre style. And now it sits under the bench.
     
    Last edited: May 1, 2012
  4. Lurk king
    Joined: Dec 12, 2011
    Posts: 197

    Lurk king
    Member

    Here is a link to " hotrod cards" linkage page. It shows there man-a-free style 4x2 setup that I plan on installing on my setup when I get motivated to work on it again.


    http://www.hotrodcarbs.com/parts.php?Linkage_Kits


    and a pic of my setup on my motor as I was getting it all buttoned up.
    It's kinda hard to see in this pic but I made some 1.5" spacers under the carbs.

    [​IMG]
     
    Last edited: Apr 30, 2012

  5. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Thanks for the response, my buddy had a weiland 4x2 and said it ran amazing, don't know if I should wait to get one of those intake manifolds or take my chances with the Offy.


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  6. Lurk king
    Joined: Dec 12, 2011
    Posts: 197

    Lurk king
    Member

    I don't know much about the setup, except I've read it's pretty much better than the offy in every way haha.( Dual plane and the option of progressive linkage.)

    But I do think the offy can be awesome if the whole package, ie cam,heads,tranny/stall,gear ratio,etc. Is designed properly. I believe my only downfall was a bad choice in linkage.
     
  7. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Lurk king, thanks for the link, the Offy setup looks good. My 327 has just a cam and stock camelback heads, with a power glide. Probably wouldn't do more motor work.


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  8. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Looks like I will be running the Offy 4x2 intake. If Any one has any pics of there setup that would be great


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  9. Get the Weiand Staggered 4x2...... I know people who ran the offy's 4x2 and went back to a 3x2..... I just sold my Weinad 4x2... Nice setup!
     
  10. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Im getting a lot of mixed reviews, I read some people have great experience with the Offy just depending on what carbs your running. The weiland I herd is a great set up but the manifold is so hard to find by itself


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  11. Say "Why-And"

    Look up Brad O'cock's article in Hot Rod Delux I think it was. He dyno tested a small block with my Offy 4 x 2 intake. It had double (low) digit HP numbers in the low RPMS and then surpassed all the other intakes he tested at high RPM. It is a good drag manifold for WOT. Basically it is just sets the carbs over the intake ports like injectors.
     
  12. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Tudor do you know what carbs he tested with your manifold? I'm not looking for big horsepower i want the good look and reliability for when driving around town.




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  13. He used those Speedway 97 Copies. The 3 x 2 with progressive linkage would be much better for around town performance.

    That offy 4 x 2 would be just a gigantic vacuum leak and probably be very diffucult to keep idling unless you were idling at 3000 rpm.

    Think about 4 rochester 2 barrel carbs trying to share the idle vacuum signal and drip gas over the intake ports. You'd have a ton air getting let in with the 4 times the idle fuel you normalle need - oh what a nightmare.
     
  14. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    Tudor, I would be running Rochester carbs too. Is it just the way the manifold is designed and thats why it would cause issues?
     
  15. Yes, with a 3 x 2 intake the engine idles on the center carb and the outer are special carbs with butterflies that shut/seal completely so everything idles annd runs off of the center carb until you open up the outer carbs with your progressive linakge. The outer carbs are just venturis and start feeding fuel when they open up.

    3x2 outer carbs also typically don't have idle circuits if they have the correct butterflies that shut completley. The center carb butterflies stay open a bit to feed the idle mixture air.

    I say outer carbs typically don't have idle circuits because some people do run 3x2 set ups with all three carbs utilizing idle circuits. More difficult to tune and get right. GM did it with special outer carbs as described above. easy.

    With that 4 x 2 intake design, basically the head ports only get fuel from the carb directly over it. I think that is the difference in the WEIAND and the OFFY. The OFFY is basically open plenum with the carbs over the ports. The Weiand had some sort of dual plane built into the plenum. I don't hvae one of the Weiand so I am not sure.

    So with the open plenum, At idle you will have 4 x 2 (8) barrels with their butterflies cracked open letting in air. Leaning out the idle circuit. It would be like having 8 big vacuum leaks dripping gas. You'd have to reduce amount of idle air fuel drip to at least a 1/4 th of what it normally is which can be done.

    Around town - the 3 x 2 running off the center carb for idle and part throttle = GOOD

    Around town the OFFY 4 x 2 running off all 4 carbs for idle and part throttle - mostly Sucky until you could floor it and get the R's up.
     
  16. 5632
    Joined: Sep 22, 2008
    Posts: 18

    5632
    Member

    I have 4 Rochester 2G's on an Offenhauser intake. They are on a 350 stroked to 383 cu. in. I experienced a problem when first setting it up and tuning. You must have power values and power pistons. Not like #1 and #3 on a 3x2 set up. I have only over 1000 miles on it but it starts and runs great. To my surprise I get better gas mileage than I ever expected.

    When building it I had one opion that you should have at least 350 cu.in. But I cannot confirm.
     
  17. lucky23
    Joined: Feb 9, 2010
    Posts: 166

    lucky23
    Member
    from So Cal

    I spoke to a guy today that was running the Offy 4x2 setup on his truck with Rochesters and said it ran fine around town. I'm guessing it's all in the way you tune it.


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  18. 5632
    Joined: Sep 22, 2008
    Posts: 18

    5632
    Member

    Absolutely correct. You must adjust the throttle plates first for all 4 carburetors so that they have equal vacuum and than adjust the idle screws.
     
  19. Im right now working on a model a project with a 283cui and a Offenhasuer intake, sporting 4 Rochester 2J 's. Trying to figure out a linkage that'd work, as i have nothing for the moment..Might just build it piece by piece..
    Anyone with pics out there??
     
  20. jcmarz
    Joined: Jan 10, 2010
    Posts: 4,633

    jcmarz
    Member
    from Chino, Ca

    I am not sure if it was Hot Rod or Rod n Custom magazine that ran a test of 4 barrel, 2x4, 3 twos and four twos on a small block 283 and the 4 two intake performed the best but only above 4 thousand rpms. The 2x4s were best all around. This was a recent test. If I can find the magazine, I will post what they said about the 4 twos.
     
  21. snakebit7
    Joined: Sep 19, 2011
    Posts: 11

    snakebit7
    Member

    Any more info on this subject would be appreciated. I have a 350/300 hp crate motor with this set up and 4 rochesters without power valves. Got it idling well and running well around town. Still some hesitation when you stomp on it though. Runs rich as well. Running #57 jets in carbs. I advanced the timing a bit and opened the gap in the plugs. It's better but not as crisp as I would like.
     

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