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QJet power problems - Edelbrock 1910

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by KRAZIE87K5, May 15, 2002.

  1. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    This is going to be long folks... so sorry for that in advance. Please read below for the sorry excuse for communication that I had with an Edelbrock tech today via email:

    If you are looking for more power, you can really only experiment with it, you'll have to keep an eye on the spark plugs, they will tell you if the motor wants more fuel or not. Really all you can do is try to use a bigger jet or rod and see what happens, we really do not offer a tuning chart for making more power because every motor is going to want a different fuel curve.

    Shane Turner
    Edelbrock Tech Dept.



    -----Original Message-----
    From: Dan Dycus
    Sent: Wednesday, May 15, 2002 7:37 AM
    To: edelbrock@edelbrock.com
    Subject: Questions on the 1910 QJet offroad carb


    Greetings!

    I recently purchased the 1910 QJet from Summit Racing, and have a few questions about how I can pull more power from this carb, and maintain the stability of this carb while off-road.

    Let me give you a brief history. I have an 86 K5 Blazer, with a 454. It is mostly a stock engine, with a BBC air-gap intake, and the 1910 carb. Stock fuel pump, running a regulator set at 6psi. The distributor is a Mallory Hi-Fire, and the coil is a MSD Blaster 2 offroad. Taylor 8mm wires. 39.5" tires, 1 ton axles, and a manual transmission. I use a Comp Cams 11-206-3 cam, here are the specs:

    Intake Exhaust
    Valve Adjustment 0 0
    Gross Valve Lift 0.46 0.485
    Duration At 0.006 Tappet Lift 255 261

    These Specs Are For The Cam Installed At 106 Intake CL
    Intake Exhaust
    Duration At 0.05 203 212
    Lobe Lift 0.271 0.2853
    Lobe Separation 110

    http://compcams.com/information/search/CamDetails.asp?PartNumber=11-206-3

    My software dyno reports that I should be able to pull over 420HP, and 480lbsft. of torque with this combo!!!

    I used to have a Holley 750cfm double pumper, which I was very happy with for street use, but my truck is made for offroad use. So I bought the 1910. After installation, I was really dissappointed in the loss of power, throughout the power band. I have only tried small adjustments, and have
    not changed metering rods, jets, or anything else.

    I need to know what to do to bring the performance out of this combination. I really had quite a bit of power with the Holley, and now its really pretty frustrating. I spent $500 on a carb that I had "high hopes" for, and I believe that the power is still there, and I just need help figuring out what to do to extract it! =)

    I will say that I was very happy with the offroad performance of this carb though! I can nearly dump the truck bumper over bumper, and the engine keeps right on ticking! Only under very tough bumping and jolting does the 1910 stutter. Are there any other modifications I can make to this carb to
    make its offroad capabilities even better? Like maybe installing your "offroad jets?"

    Please advise as to what I can do with this carb to KEEP THE STABILITY (first and foremost), but get the power out of it that I used to have with the Holley. Thanks for your time, and sorry for the long winded email!!!

    Regards,

    Dan Dycus
    Infrastructure Security Specialist
    Sr. Helpdesk Analyst

    *BUMMED*

    Is it just me, or did the dude like just blow me off?!!! /forums/images/icons/mad.gif At any rate, I still am interested in learning how to tune my Edelbrock to make MORE power, like I had with the Holley. Suggestions? I hate lazy people who don't help for a damn! /forums/images/icons/frown.gif Thanks for letting me vent some... /forums/images/icons/wink.gif

    -Dan
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Dan...you sorta got the blow off in MHO. That being said the Q-jet will never make the same power as you had with the holley. For power tuning I'd say Doug Roe's book on Q-jets will get you farther than any email from Edelbrock. The Q-jet should have very crisp response off idle though...

    How is it at WOT? Does it make decent power once the secondaries kick in? About the only thing I know can really be adjusted is the metering rods and jets and the secondary air valve opening. The risk is ending up with Quadra-bog if the secondaries start opening to soon or too quick.

    Is the choke opening up all the way as it warms up? The Q-jets I've had have linkage that prevents the secondaries from opening up until the choke is wide open. Maybe the secondaries just aren't opening or they're getting hung up on that linkage?

    In the end it still won't make the same power as the Holley, but the difference should be all at the top end (4000 RPM and up)

    Rene
     
  3. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    And that is what I expected!!! I bought the carb, because I was so tired of the Holley's low end power, and the HORRIBLE offroad problems I was having. So instead, I get the 1910. Honestly, I was fairly dissappointed when I installed it at first, but I grew to appreciate the offroad gain - and forgot about the power loss! /forums/images/icons/frown.gif WOT is still trouble with the 1910 - it still boggs if you stomp it from a standstill, and high RPM 3000+RPM power is sluggish. The holley used to PULL like he!! on the top end... but I don't need all that. I just want the power in the bottom end, and some top end power back.

    Know of any place online where I can get that info Rene? I'm too lazy to get to a real bookstore! /forums/images/icons/laugh.gif

    -Dan
     
  4. Goober

    Goober 1/2 ton status

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    The 1910 won't make top end power ??? That carb is PERFECT for making gobs of power with an engine like yours!

    First of all, I am not really an expert but I have built probably hundreds of quadrajets in the last 20 years and I have had great luck making them work.

    That overpaid doorknob from Edlebrock doesn't know what he is talking about, thats why he blew you off.

    Go out and get a copy of Doug Roe's book "Rochester Carburators". That book has all the information you need to get your carb working.

    For a few quick checks, make sure your secondaries are opening /forums/images/icons/smile.gif and make sure they are opening at the right time (tighten the spring just enough to get rid of the dreaded BOG). Next, make sure your float is set PERFECT! Quadrajets are really finicky about float settings.

    If you want to get the optiimal performance out of it, get Edelbrocks tuning kit for the Quadrajets. It will cost you about $100. and it will have a selection of primary rod hanger springs and different rods and seats along with some other goodies. Well worth it if you like to tweak.

    One final thought ... anyone who says that a Quadrajet can't make as much power as a Holly (especially an 850cfm monster like yours) is just ... um ... lets see ... how do I put it nicely .... ... ... ... Lets just say they just can't tune a Quadrajet correctly. /forums/images/icons/wink.gif

    Have fun
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Fine...take an 850 Holley and your Q-jet and do the dyno thing. I personally hate Holley carb's but I'd bet the Holley will make more top-end power than the Q-jet any day.

    Rene
     
  6. Thunder

    Thunder 3/4 ton status

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    i'm not going to get into the holley vs Q jet debate but you should be able to tune that Q jet to perform up to your expactations
    Here's the link to Doug Roe's book :<a target="_blank" href=http://www.amazon.com/exec/obidos/ASIN/0895863014/qid=1021505850/sr=8-1/ref=sr_8_1/002-0534334-2552825> Amazon .com/doug roe</a>
    You probabally need bigger jets. The carb you got from edelbrock is probabally one of their generic carbs jetted for a 350. You can get a kit with a bunch of different jets and meetering rods from Edelbrock.
    Or you can order them seperatly.
    Or if you want to save money and hassle
    If you still can. Send that EDEL carb back and get your money back and get a Q- Jet from:
    <a target="_blank" href=http://www.jetchip.com/> jetchip.com</a>
    They will build you one set up to match your engine's needs. They do very good work and are about the same price as Edelbrock. Their stage 2 carbs work very well
     
  7. Goober

    Goober 1/2 ton status

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    Hmmm ...

    I've built both. I've built carbs for small blocks, big blocks, trucks, 4x4's, sedans and race cars. In my experience Quadrajets make more power and can be tuned better to match an engines fuel needs.

    But what really matters is what YOU are most comfortable with since you will most likely be the one working on it.

    I must admit that Holley's are much easier to adjust then Q-jets, but I prefer to do a little extra work to get better performance.

    /forums/images/icons/smile.gif
     
  8. 79Beast

    79Beast 1/2 ton status

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    I just bought a 1910 Edlebrock. It makes similar power to the stock quadrajet it replaced. My stock Qjet died and I decided to go ahead and buy the 1910 because I am getting up the parts to build a roller cam 468. The secondaries don't open as hard as the stock one did. I can't tell if it is just smoother, or if it is not as strong. It is running just a tad rich at idle and sometimes the idle can be inconsistant. Any suggestions on adjusting the mixture and getting it to idle at 650 RPM every time?
     
  9. Greenblazer-AZ

    Greenblazer-AZ 1/2 ton status

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    I also need help in this area. I took my truck to a mechanic that I trust to help get my truck too pass emmissions here in Phoenix, AZ. After several times through emmissions he told me that my Q-jet carburator had been modified and could not pass. His policy is to not charge if the vehicle doesn't pass so he lost money on the deal so far. I told him to go ahead and get a new rebuilt Q-jet but he couldn't find one that would work, so he told me that I would have to special order it. So now what do I buy an Edelbrock Q-Jet or a Jet Q-Jet or should I order the stock rebuild? Passing emmissions is a priority because my tags expired in April. Getting more power would be nice so spending a little extra would fine with me. "Little extra" being key words so don't bother suggesting fuel injection. Compairing Q-Jet to Q-Jet which will work? BTW the problem finding the right carb had to do with the choke hook-up to the Edlebrock intake manifold. They tried seven different carbs and none had the right set up. I would think that the Edlebrock Q-Jet would have the right hook-ups for the Edlebrock manifold, but is it worth the 200 extra bucks? How about the Jet Q-Jet is it worth the 100 bucks more than the stock one? Please HELP! I wan't to do it right the first time. Will these carbs pass emmissions dyno sniffer tests? I'm not too worried about them being "Smog Legal" by having the adjusters plugged as long as it will pass. The 350 engine is mostly stock with headers and Edlebrock intake manifold. I rock crawl this rig so the Q-Jet is the only carb that will perform properly, but which one?
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Not to start a huge flame war, but how, if two carbs can deliever the same amount of air and fuel, can one produce more WOT power than the other?

    I only bring this up because I've heard it before, but have never seen ANY test where someone that knew a Q-jet built and tuned it, then had that motor/carb combo tested against the same engine but with another manufacturers carb that was equally well tuned.

    I've seen/heard Q-jet cars going 10's in the 1/4 mile, and I have a feeling the power aspect is nothing more than people not knowing how to tune the Q-jet. Never having owned another type of carb than the Q-jet, I can't comment on how hard mods are, but secondary air valve, secondary rods/hangars, and priamry jets/rods can ALL be changed with a maximum of pulling off the air horn.

    Seriously though, if someone can explain how two carbs feeding air/fuel at the same rate can make more power than another, (tuned, not an 800Q-jet on a 305 vs 600 holley on a 350 with the right rods/jets) I'm all ears.
     
  11. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Dan,

    Sounds like a "brush off" to me too. Now that I've got my fuel pressure problem fixed, by 1910 is behaving well......the only thing I have now is an occasional "stumble" after an extended period of full-throttle acceleration. My regulator is set at 4.5 Lbs currently....maybe that's a bit too low?

    One of these days, I'm going to find a local Q-Jet expert to really "dial in" my jetting. I spent the extra $100 for the Edelbrock "Jet Kit" so it would be nice to actually use them and do the fine-tuning on the carb.

    As a Q-Jet newbie, I can't offer specific advice but I would have to say that the "factory jetting" is more likely to be wrong for your engine....than it is to be PERFECT. I think it's just going to me a matter of measuring the A/F ratios, and "adjusting all the adjusters" to get it where it should be on your motor.
     
  12. smartpatrol

    smartpatrol Registered Member

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    Just a thought do you have the stock air cleaner? I just did an engine swap in my blazer and used the old Q-Jet from my 305 to put on my 500. It was bogging when i would open the secondaries. so i flipped the air cleaner lid over and waalaaa problem solved, huge noticeable difference. Sounds simple but worth a try.
     
  13. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Nope - I've got the "tall" K&amp;N cleaner on the engine right now... but good thought! /forums/images/icons/wink.gif

    -Dan
     

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