Holley EFI, Quadrejet or 4bbl?

Discussion in 'High Tech for Old Iron' started by MatVDD, Feb 12, 2020.

  1. MatVDD

    MatVDD Member

    Hi guys and gals.
    First post for me here, 1969 Skylark Custom 350 here, bonestock and looking to build it up for cruising.
    I've been looking through some EFI threads but couldn't find anything to conclusive.

    Short question:
    TA performance Stage 1 manifold. Which EFI combination is best, Quadrajet or 4bll?

    Long question:
    I want to install a Sniper EFI system with Hysperspark ignition and combine it with at TA Perfomance intake manifold.

    Either the Stage1 manifold: http://www.taperformance.com/proddetail.asp?prod=TA_1235
    Or the SP3: http://www.taperformance.com/proddetail.asp?prod=TA_1236

    Seeing as the Stage1 is more street friendly I thought about getting that one, but do I get the Quadrajet EFI for that manifold or just the 4bbl?

    Or is there another benefit for getting the SP3? Or another brand intake manifold for that matter?

    Thanks in advance for any enlightenment.
    It'd be appreciated.
  2. sriley531

    sriley531 Buckle up, this could get rough....

    If you're dead set on EFI, they traditionally work better on a single plane intake (SP3 in this case) over a dual plane. They will work on a dp, but are better suited for a single.
    Ryans-GSX likes this.
  3. Electra Bob

    Electra Bob Well-Known Member

    If the engine is otherwise running fine and you don't plan on any major work the Sniper Quadrajet will plonk right down on the stock manifold. That being said you are still looking at having to upgrade fuel delivery. I went all in and replaced everything from the filler cap to the Sniper but if the existing tank and fuel line is in good shape the FiTech Command center might be an option.

    12lives likes this.
  4. MatVDD

    MatVDD Member

    Hi Bob, Thanks for the info.
    Yes I'm indeed looking at buying the master kit so the fuel system is taken care of.
    Just wondering if there are pros and cons to the Quadrajet or 4bbl since I do want to change the intake manifold in one go as I'm changing out the carb anyway.

    So from what I get from Sriley531 is to get the SP3 single plane manifold with a 4bbl Holley EFI?
    Is that about right?

    Thanks for all the feedback guys.
  5. sriley531

    sriley531 Buckle up, this could get rough....

    If you're looking at it from the best functioning standpoint, yes, the single plain will be best. But a dual plane will still function ok, it's not a deal breaker.

    For the record i replaced a very nicely tuned Holley 4150hp with a Fitech system in the green car and have no regrets.
  6. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Yes a SP-3 intake and self tuning EFI
    72gs4spd likes this.
  7. MatVDD

    MatVDD Member

    Jeezus Shawn, just went through your build thread on the "Rusty Hulk", props to you mate, seriously awesome build.
    makes me want to get a Stage2 hood so badly now...

    The only thing that was putting me of the single plane intake manifold was the fact that TA Performance didn't recommend it to me since the engine was stock and meant as a cruiser.
    But if you guys say it's the best option anyways, that gives me some future proofing if I want to get some more performance parts on there in the future.

    Just double checking here (as I've got no prior American engine experience), the Single plane SP3 Square Bore is the one that fits the 4bbl EFI?
    And spread bore is for Quadrajets then?
    sriley531 likes this.
  8. 12lives

    12lives Engage! - Jean-Luc Picard

    Welcome - My opinion, I think you need to figure out what you are trying to accomplish. You need to remember the engine is a system of parts. Are you going for more power? Do you want to maximize MPG? Do you just want it to start easy? Is there an issue you are trying to solve? Adding a high buck EFI to a tired 350 may not do what you want. Having one of the experts here freshen up your Q-jet might.

    My 2 cents: The Q-jet starts great, gives good MPG and power (when properly set up), and would require no mods to your engine. It would be great for cruising! The stock intake is very good, just heavy. A full tune-up to the ignition system will be beneficial or switching to a factory style or OEM HEI is a big improvement. So for little money and effort you would be well on your way to happy cruising.

    Of course I'm thinking about about the best bang for your buck. On a 50 year old car there are always things that need fixing, suspension, HVAC, bodywork, etc. Many of those items, in my experience, gives great satisfaction to me when I'm cruising. I guess I think of EFI as icing on the cake!
    Last edited: Feb 13, 2020
    pbr400, jamyers and Darron72Skylark like this.
  9. MatVDD

    MatVDD Member

    Thanks for your input mate, I appreciate it.
    And yes, you are exactly correct. This is mostly what I'm thinking aswell. The Skylark is in great condition. Bodywork is absolutely flawless and as far as I can see, everything is stock and in great condition.
    Suspension (getting it a bit lower in the front) and some nice brakes are on the shortlist aswell.

    What I was looking for was a project car to sink my teeth in, but eventually I got a car that needs little to no fixing up.
    So upgrading stuff is the next logical step.

    Found this forum and a lot of people are talking positive about this EFI conversion. Seeing as it's very doable to do yourself and in the process get some better milage and practical use out of it, all that would be a plus.
    Since I'm diving into the engine bay anyways, I recon I might aswell get the old girl a decent new air intake manifold aswell.

    Now, I'm partaking in a rally across Europe (+-2000mile trip in about a week) around July this year.
    Reading about the increased reliability at cold starts, some possible fuel savings (ow yes, gasprices are getting rather expensive over here), the elevation differences we'll encounter during the trip,...

    All this lets me think that investing in an EFI system would pay itself back multiple times during this trip.

    Long story short, what am I looking for?
    -Better MPG, but seriously, I wouldn't have bought a V8 if I wanted Prius fuel economy...
    -Reliabilty, without having to retune a carb halfway up the Stelvio Pass.
    -A future basis to get some more power down the line, if I would ever want that.

    Thanks for hearing me out guys, I'm open to your ideas and suggestion.
    I've got some experience working on motorcycles and european cars but I'm a real novice at American Muscle.
    But i'm itching to dive in.
  10. pbr400

    pbr400 68GS400

    GM didn’t know where its cars were going when they left the plant (with a few exceptions) or where the proud new owners were going to drive them. So, they had to be right for Atlanta, Detroit, Miami, Houston, Seattle, Denver, Phoenix, etc as delivered. The Quadrajet is an amazing feat of engineering that is barely equaled by fuel injection half a century later. I’d rather set that carb up right, possibly carry a spare that’s known good, and maybe a fuel pump. I’d rather trust GM’s simple, proven and easy to service system. You don’t see as much excitement about qjets because, well, they work well for a long time and aren’t hard or expensive to fix when they need service. Fuel injection is an expensive and complicated fix to a simple problem. In my opinion.

    —And you’ll never save enough fuel to pay for FI.
  11. sriley531

    sriley531 Buckle up, this could get rough....

    I have EFI and love it. But based on your posts, I think some power timing via Larry's thread and a nicely tuned qjet is where I'd go with your car. The cost vs return potential is very high with that scenario. If I were you and this was my car, that's the route I'd take. (Actually that IS the route I'm gonna take with my white car eventually).
  12. 72gs4spd

    72gs4spd Well-Known Member

    Should have my sniper up and running for springtime on the existing motor. This way if I was to make a catastrophic boo boo it won’t hurt the pocket. Hoping to have the replacement motor from the machinist by fall beings the block past inspection. Oil mods done, now he’s checking the squareness of the deck to crank. Will be getting the SP-3, aluminum heads, roller cam, forged rods, autotech pistons 60 over. To name a few. Haven’t sat down with him to hammer out all the details, but he knows where I want to be.
  13. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

  14. MatVDD

    MatVDD Member

    Hi Shawn, Might have forgot to mention that I've got the 2bll carb currently in the Skylark, so upgrading to a 4bbl EFI is another reason of doing so.

  15. sriley531

    sriley531 Buckle up, this could get rough....

    I was aware, my white car is a 2 barrel as well, which is why I referenced it. My line of thinking in that comment was that going qjet will get you almost there performance-wise, but for considerably less coin. You figure you'll need a manifold either way, so thats a wash. But a FI system after all the necessary fuel system upgrades is going to run you about $1,000 (off the cuff guesstimate) more than a qjet set up. Now I'm very much an advocate of FI, and while I think it is better, my opinion is it wont be $1,000 better. Obviously you're viewpoint may be different. But that same $1,000 saved going to qjet route could get you additional upgrades like gears, headers, etc that combined with the new qjet would net you noticeably superior performance compared to FI alone. Again, not saying one way is right or wrong, just breaking down the thought process behind my opinion as something to maybe consider.
  16. MatVDD

    MatVDD Member

    Thanks for all your feedback guys.
    So to summarize all posibilities,

    -Either I keep the stock 2bbl as it seems to be considered a solid carb when tuned correctly.
    -I upgrade to a Quadrajet carb, but I would imagine I'll be needing a new intake manifold then? The TA Stage1 dual plane will be best for a stock Quadrajet then?
    -I spend some more and get the TA Performance SP3 intake manifold with a 4bbl EFI sniper kit.

    Those are the best combo's for this 350-2bbl stock engine to go with?
  17. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Surprised no one has mentioned this so I will, for better "cruising" get some better gearing in that thing!

    You more than likely have a 2.56:1 rear gear which doesn't help your off the line performance and adding a 4bbl won't make much of a difference with that rear gear. Swap in a 3.42:1 or numerically higher rear gear up to a 4.11:1 and a 200R4 overdrive trans before even messing with the engine. A standard Corvette or GN converter would work great.(1,800 stall)

    Is that a 2 or 3 speed auto trans? If it has the 2 speed trans, OH YEAH the gearing will make a huge difference!

    Better gearing in your car would make the biggest difference that you will actually feel it being "faster", off the line and every time you downshift. Add the 4bbl or FI next year, I guarantee the better more modern gearing will make a bigger difference than a 4bbl and to top it off you'll get better MPG than you're getting now.(that is if you can keep your foot from hitting the floor after every light turns green!:eek::cool:)
  18. 12lives

    12lives Engage! - Jean-Luc Picard

    Congrats on getting a nice car! Its always best to get the best condition car you can afford up front even if you plan on changing it later. I am thinking about the 2000 mile trip you plan to take: Derek has a great point about going with a better trans and final drive ratio. If you go with EFI you might want to go with a computer controlled trans like a 4l80e and link them together with the TCU.
  19. BillA

    BillA Well-Known Member

    Throttle body EFI will work fine with a dual plane intake. I ran a Holley Terminator TBI with a B4B intake and it performed flawlessly. All you need to do is use an open spacer or notch the intake plenum so the TB unit sees constant vacuum (manifold pressure) Since the B4B is a spreadbore manifold I had to use a square bore adapter which essentially serves as a spacer and therefore the unit saw vacuum regardless of which cylinder was firing. Whether or not to ditch a carburetor for throttle body injection is up to you, I’m simply pointing out that you do not have to invest in a single plane intake. Especially if the motor’s configuration would not otherwise benefit from a single plane.
  20. CraigFaller

    CraigFaller Well-Known Member

    For anyone going down the TBI route, plan for more cost than just the TBI kit.

    I know it’s not a Holley EFI, but I just finished installing a FiTech unit on my 350, running an SP3 intake. A few things for sp3 compatibility if you decide to go to the single plane intake:
    • Need a drop base air cleaner for hood clearance and a shorter filter element. I had bought an air cleaner from TA a while back (the one with the filter element lid). The drop base from that one worked perfectly with a 2.5” K&N (p/n E-3735)
    • Drop base to throttle body spacer ring to clear my 90 degree fuel line fittings on the throttle body (spectre sells them)
    • I also needed to modify my throttle cable. An adjustable throttle cable bracket helped, but I had to shorten my throttle cable by about an inch or more. I’m at 97.5% on the TPS now. https://www.amazon.ca/dp/B081C9WMPW/ref=cm_sw_r_cp_tai_GuytEb7022K9V
    • I needed a throttle linkage bushing for the FiTech to run the upper/front-most opening on the linkage for better throttle geometry (Moroso p/n 64920). You’ll need a throttle ball stud to fit it.
    • New air cleaner hold down stud, or an adapter to use the factory size. FiTech has a larger thread size. Moroso also makes an adapter for this.
    Regardless of engine or brand of efi kit, getting a proper EFI capable fuel delivery system is key. Budget for an upgrade to ensure the efi system will work properly. I went with Tanks Inc and it went together seamlessly but it’s a big increase in cost.
    Last edited: Mar 2, 2020

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