lets pick a carb

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    Author Topic: lets pick a carb  (Read 3996 times)

    Offline dougs bs23

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    lets pick a carb
    « on: January 02, 2015 - 12:35:33 AM »
    late Christmas present to myself will be a new carb.  So I think the choices are   proform 67258 or 67257 quickfuel  ss735, qf ss 750 or maybe something someone here recommends.
    This will go on a 70-340, lunati cam 60403  494,513 lift, lobe lift 329,342 adv dur 271,279 dur @ 50 226,234  eddy airgap rpm intake,  dougs headers d 453 on 2-1/2" X pipe exhaust,  tci breakaway 2200/2400 stall  tf2 kit with all new clutches and steels right now theres a 2:76 rear but I plan on changing that out at some point to either 3:23 or 3:55.
    So who recommends what and why?  this will be street driven but sometime may just want to get a little wild with it.
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    Offline cudabob496

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    Re: lets pick a carb
    « Reply #1 on: January 02, 2015 - 02:35:19 AM »
    for street, lean towards smaller cfm, than larger, as your throttle response
    and quickness on the street will be better. Also, annular boosters can make
    you quicker as well, and generate more power, than dog-leg, from what I've read.
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline dougs bs23

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    Re: lets pick a carb
    « Reply #2 on: January 02, 2015 - 08:36:27 AM »
    so annular boosters have better response.    looks like the QF  ss750 an is actually 735 cfm with the annulars.
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    see Bill run  go Navy football///fly navy

    Offline cudabob496

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    Re: lets pick a carb
    « Reply #3 on: January 02, 2015 - 09:24:38 AM »
    Quote from: dougs bs23 on January 02, 2015 - 08:36:27 AM
    so annular boosters have better response.    looks like the QF  ss750 an is actually 735 cfm with the annulars.


    Below is one of many discussions on the net.  Kinda supports what I have read elsewhere, that annulars,
    in general, will make you more power, and be more responsive, throughout the rpm range. I have heard that dog-legs will make more power
    if you are flat out WOT, like in a quarter mile. 

    http://www.hotrodders.com/forum/annular-boosters-real-deal-marketing-hype-65437.html
    « Last Edit: January 02, 2015 - 10:33:45 AM by cudabob496 »
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline dougs bs23

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    Re: lets pick a carb
    « Reply #4 on: January 02, 2015 - 02:04:55 PM »
    found this and seems like a good price too 
    Quick Fuel Technology SS-750-AN 750 CFM Street Carburetor with Annular Boosters
     

    by Quick Fuel Technology

     
         2 customer reviews 
     
     
     







    List Price: $604.56
    Price: $513.97  & FREE Shipping. Details   
    You Save: $90.59 (15%) 




     Only 3 left in stock (more on the way). 

    Ships from and sold by Amazon.com.
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    see Bill run  go Navy football///fly navy

    Offline cudabob496

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    Re: lets pick a carb
    « Reply #5 on: January 03, 2015 - 11:00:13 AM »
    wow, that is a good price, when you beat Summits $604
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline YO7_A66

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    Re: lets pick a carb
    « Reply #6 on: January 03, 2015 - 12:58:07 PM »
    I have been running the QF SS-750-AN double pumper for three years now on my 340. It has very good throttle response and I can adjust any circuit on the carb. I run two O2 sensors now for two years and I have the carb dialed in for a street car running on E10. My last drive showed the fuel curve as:
     30mph : 13.8
     40 mph : 14.2
     50 mph: 14.0
     60 mph: 14.0

     I love this carb for a street car! QF calls this a 750 but they said that it is 735.
     I have had to do quite a bit of tuning to get the dp to work well on the street and now that I have it dialed in, no more vacuum secondaries for me with this setup.

     I noticed that your setup shows a 22-2400 converter and 2:76/3:55 gears. I would not recommend this dp carb for your setup. It would be tough to limit the secondaries enough for your setup. I would suggest using a QF vacuum secondary carb with your setup. These 340's are not torque monsters and they are easy to over carb off idle.

     Note: When I first had this carb, I had 3:55's and a 3500 converter. I think that this was borderline for this dp carb. I now run a 3800 converter and 3:91's and 27" rear tires (same tire as previous setup)  and I love this combination on my 70 Challenger.

     If you are looking for another QF carb, the 750 Slayer would be a good street carb too.
     http://www.quickfueltechnology.com/carburetors-slayer-series/slayer-series-carburetor-750-cfm-street.html
     
    « Last Edit: January 03, 2015 - 02:29:46 PM by YO7_A66 »
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    Offline dougs bs23

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    Re: lets pick a carb
    « Reply #7 on: January 03, 2015 - 09:53:24 PM »
    maybe ill just continue to work on the qf  hr 680 I have,,   its been quite a pita and runs rich. also will stall out at a red light/stop sign.   maybe the pv is to low causing it to do this,,   4.5 pv and 13" hg idle in N around 7 in d
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    Offline YO7_A66

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    Re: lets pick a carb
    « Reply #8 on: January 04, 2015 - 09:17:14 AM »
    The QF HR 680 is an excellent start!
    http://www.quickfueltechnology.com/carburetors-ss-series/street-carburetor-680-cfm-vs.html

     (Jet extensions/notched float make this carburetor strip ready while 4-corner idle, electric choke, adjustable secondary housing, and screw-in air bleeds help tune it for the street.)
     
      4.5pv, 13”hg idle & 7”hg in D: You are losing 6”hg from N to idle in D which points to carb or timing adjustments. This could be why it wants to stall at a stop.

    - What is your timing in N
    - What is your timing in D
    - What distributor/ECU are you running?
     If you are losing any timing between N and in D, then this is part of your problem. If so, then the timing must be corrected first before tuning a carb.
    « Last Edit: January 04, 2015 - 09:56:27 AM by YO7_A66 »
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    Offline stinger

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    Re: lets pick a carb
    « Reply #9 on: January 04, 2015 - 09:38:31 AM »
    IMO it's hard to beat the six pack on a 340,best set up I ever had on a small block. the only rub is the cost :money:
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    Offline dougs bs23

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    Re: lets pick a carb
    « Reply #10 on: January 04, 2015 - 12:47:08 PM »
    this thiings been killin me for a while and at times im ready to totally give up on it.  quite frustrating for sure.  would love to find someone local that knows more about tuning carbs and let them work it out for me.   you local?
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    Offline YO7_A66

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    Re: lets pick a carb
    « Reply #11 on: January 04, 2015 - 02:05:35 PM »
    I am not local but if you can answer a few questions, someone might be able to help you out.
     You have a bunch of good parts on that motor! It should be a blast to drive.
     Can you get us the timing in N and the timing in D with the engine running at driving temp? Also, give us the rpm at N and in D.
     If you can help us out, then I would assume that we can help you out too!
     But we need to find out if your timing is good before trying to tune the carb.
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    Offline Chryco Psycho

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    • 70 Challenger R/T SE 70 tube Chassis Cuda now sold
    Re: lets pick a carb
    « Reply #12 on: January 04, 2015 - 09:55:13 PM »
    The QF 680 should work well , everything needs tuning in , I have a tuning guide in the archives work through that in order , make 1 change at a time & you should get close . I can always jump on a plane & help just not at this time of year !!
     Anyone want to drive for us ??
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