Anybody running an SP3 with a Quadrajet?

Discussion in 'Small Block Tech' started by Skippy597, Jan 10, 2018.

  1. stk3171

    stk3171 Well-Known Member

    Skippy
    This car only runs 9.20s in 8th . This motor is bone stock test mule car.
    The NHRA car runs 7.40s in 8th. 11.90s 1/4.

    Dan
     
    300sbb_overkill likes this.
  2. 70skylark350

    70skylark350 Jesus loves you unconditionally

    Hi Skippy, I am building a 350 now and was debating what intake to run. what did you end up doing? are you running the SP3?
     
  3. Skippy597

    Skippy597 Silver Level contributor

    Not yet but will likely end up there. I am just currently running a stock iron I'm take with the dividers cut out and 1" spacer for my quadrajet. Stock engine for now just headers and small stuff.
     
  4. 70skylark350

    70skylark350 Jesus loves you unconditionally

    for a mild built street motor will the SP3, with the proper carburation, perform better that the stock or DP intakes ?
     
  5. alec296

    alec296 i need another buick

    Depends on cam rpm range , torque converter range,and gear. The sp power would be up higher in rpm.
     
  6. Jclstrike

    Jclstrike Well-Known Member

    I find all this interesting as I have struggle to get my Qjet to run flawlessly with the sp3 on the street. I find when the rpm's are up the qjet works just fine but from idle or low rpm is the only problem times. Has anyone found a good recipe for the Qjet with the sp3?
     
    Mark Demko likes this.
  7. alec296

    alec296 i need another buick

    Sounds like you have to tune more, do you have enough gear , converter and timing recurve for your combo? Did you degree cam?
    Put a vacuum gauge on it, see if it’s steady and has enough vacuum at idle. It can also be in cam specs
     
  8. Mark Demko

    Mark Demko Well-Known Member

    I TRIED to get my Q-Jet tp play nice with the SP3, easy casual throttle its fine, idle is fine, drivability is great, but its when you SLAM the throttle wide open the Q-Jet falls on its face.
    I've mentioned this before, there's no accelerator pump for the secondaries, so when the throttle is slammed wide open, for a second it goes way lean, and when it goes lean for that second, it falters.
    Remember, the Quadrajet is a MECHANICAL secondary carb WITH an air valve, it IS NOT a vacuum secondary type carb, the secondary throttle plates are linked to the primary throttle plates, the secondary AIR VALVE responds to engine demand.
    I love my Q-Jet on a dual plane, but not so much on a single plane.
    I bought an 850 AED double pumper, WHAT A DIFFERENCE when slamming the throttle wide open, it responds NOW:D
     
  9. 70skylark350

    70skylark350 Jesus loves you unconditionally

    Mark, Hi. I was reading just a little on that AED carb you mention. sounds more like a performance carb than for street use?
     
    Mark Demko likes this.
  10. gsjohnny1

    gsjohnny1 Well-Known Member

    I love my Q-Jet on a dual plane, but not so much on a single plane.
    I bought an 850 AED double pumper, WHAT A DIFFERENCE when slamming the throttle wide open, it responds NOW


    and................
     
    Mark Demko likes this.
  11. Fox's Den

    Fox's Den 355Xrs

    it broils the tires to the ground.

    The Lark is too heavy with not enough convertor or gears to make the Q-Jet work properly with the SP3

    I run a DBL pumper runs fine on the street. Q-Jet aint going to work with the SP3 with low gears you need a 411 to make that carb work with you on the SP3.

    Like Mark said, you slam the Q-Jet open and all 4 open up and you have that primary squirter trying to take care of all 4 bbls with that big giant hole that just opened up under the carb. boooooooog.
     
    Mark Demko and alec296 like this.
  12. 70skylark350

    70skylark350 Jesus loves you unconditionally

    so for a mild build street engine would you use the TA dual plane with the quadrajet, or an SP3 intake with a double pumper, or the stock intake? Is the TA dual plane even worth the price over a stock manifold? I know about the weight savings but other than that I have read that its basically same performance as stock, that is why I started looking at the SP3 but not sure if that is really intended for a mild or non roller motor?
     
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I'd use a stock intake. Like you said, the TA Stage1 doesn't really offer anything but a weight savings. The SP3 is for a more radical 350 with gears and converter. When the SP3 first came out, I related my experiences with the SP1 on my BBB with a Q-jet. It turned out it wasn't really very relevant as the 350 is not the 455. The SP3 will want the DP carburetor on a mild 350 in order to have seamless response. I have no problems at all with the SP1/QJ combination, but the SBB is different.
     
    70skylark350 likes this.
  14. gsjohnny1

    gsjohnny1 Well-Known Member

    70skylark350,

    made my own s/p 12 yrs ago.(next to t/a's,it's pretty close). the q/j just does not perform, not even close, like a d/p does. race car had 4.56's gear. d/p, 6000rpm, vs s/p 7500rpm shift points. rpm drop off was less than 1000rpm. still running the same engine and same 650 d/p 12yrs later on a 4-71 supercharger.
    still waiting for someone to tell me I'm wrong......
    quietly going 9.1's@145 @ 7000rpm
     
    300sbb_overkill, alec296 and Mart like this.
  15. Mark Demko

    Mark Demko Well-Known Member

    A double pumper, whether its Holley, AED, Demon, etc, will perform fine on the street, no issues.
    The Q-Jet was designed to give max fuel mileage up until max power was needed by way of the secondary air flap/doors that would slowly open as the engine wanted the air/fuel.
    Remember, below those air flap/doors, the Q-Jet is a mechanical secondary carb, BUT no secondary squirters to give the engine the initial, VERY critical shot of fuel to cover the "hole" That's where the Q-Jet falls short on the SP3.
     
  16. 70skylark350

    70skylark350 Jesus loves you unconditionally

    I think I am going to stick with the Rochester and a dual plane set up, thanks for all the input.
     
  17. blyons79

    blyons79 Well-Known Member

    Mart and Fox's Den like this.
  18. Jclstrike

    Jclstrike Well-Known Member

    Just an update I went back to my original 350 qjet and the car ran the best yet. It still was a little sluggish but mainly in third or fourth gear at low rpm's. Downshifting took care of this issue for the most part. I was pleased that for the street cruising its close enough for me. I could put more gear in the rear as I only have 3.23's in it. sp3 sure does like rpm's for sure as the car runs flawlessly during acceleration. I will check it coming out of the hole hopefully this weekend.
     
    Mark Demko likes this.
  19. Mark Demko

    Mark Demko Well-Known Member

    Glad its working better for you!
    The issue isn't more gear as far as it being sluggish, its the Q-Jets lack of squirters for the secondaries. I have 3.42's, not much deeper than 3.23's, and from a low roll or standing start, my double pumper flat blows away my Q-Jet as far as keeping the engine fueled when the throttle is slammed open:cool:
     
    300sbb_overkill likes this.
  20. Fox's Den

    Fox's Den 355Xrs

    The Q-Jet and SP3 would probably work fine with a 410 gear set or higher since the engine will be higher in rpm when stomped.
     

Share This Page