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What's a carb spacer for?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by reddog64, Mar 12, 2002.

  1. reddog64

    reddog64 1/2 ton status

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    What\'s a carb spacer for?

    What is a 1 inch carb spacer used for... any performance gains?
     
  2. Stomp

    Stomp 1/2 ton status

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    Re: What\'s a carb spacer for?

    makes more torque.
     
  3. reddog64

    reddog64 1/2 ton status

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    Re: What\'s a carb spacer for?

    is it worth it? Can you notice anything?
     
  4. 79Beast

    79Beast 1/2 ton status

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    Re: What\'s a carb spacer for?

    There are carb adapters and carb spacers. Some folks use the names interchangeably. If you are not sure which is which, ASK. A carb spacer increases the velocity of the air/fuel mixture entering the intake. Some insulate the carb from the heat of the intake, providing a cooler, denser charge. Yes, carb spacers build power. More than likely you will feel a difference. Make sure to buy one that fits your application and suits your needs. A call to Jegs' or Summit's tech line would be a good idea to match the spacer to your driving style and engine.
     
  5. Stomp

    Stomp 1/2 ton status

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    Re: What\'s a carb spacer for?

    I think so, bought mine at the local auto parts store for 20$
     
  6. Stoopalini

    Stoopalini 1/2 ton status

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    Re: What\'s a carb spacer for?

    Along with the performance gains already mentioned, the spacer will lift the throttle blades up which will allow for more clearance in the intake.

    I had a problem with the blades on my Holley getting stuck inside my edlebrock intake, so I got the spacer and it solved the problem.

    Definitely a great bang-for-your-buck add on, if you ask me.

    Thomas.
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: What\'s a carb spacer for?

    Most often a carb spacer will lose you some low end torque because you're increasing the plenem volume of your intake. As long as it's a 4 hole one though, it shouldn't cause a problem.

    I can't see why you'd want one though. It's not likely to help you gain anything on the top end, and you'll lose low end torque.
     
  8. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Re: What\'s a carb spacer for?

    With a carb adapter you will not only change from one style or bolt pattern of carb to another but you will also increase the plenum volume which will raise the torque and HP levels to a higher RPM range to the expense of low RPM torque and HP. You will probably not notice any difference unless you do other things as well but things will change slightly.
     
  9. sunco_breather

    sunco_breather Newbie

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    Re: What\'s a carb spacer for?

    yea, its good becase i have a big block 454 in a 74 k5 and a 650 cfm carb and now its breathing harder and its in need of a 800 cfm double pumper and im goin to get it. i have a 1 in. spacer.
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: What\'s a carb spacer for?

    A double pumper (mechanical secondary) carb has absolutely no place on a 4wd truck. That's a gross mis-match of parts.

    You may very well need a large, vacuum secondary carb for your application, but a mechanical secondary carb that big is not needed for most street engines...and proper carb sizing is ESSENTIAL on any rig that uses a mechanical secondary carb.

    As for thinking that a carb spacer will make you more power by increasing plenem volume...if that's the case, we should all have single plane intakes or tunnel rams on our trucks--which just isn't true.

    Vacuum is what creates low end torque and throttle response, and the closer your carb is to the intake ports in the heads, the stronger the vacuum signal will be.

    I hate to disagree with everyone here, but you guys seem to have some really screwed up ideas reguarding carbs.

    650 CFM of air in an engine that is 90% volumetrically efficient will feed a 454 to 5500 RPM. Unless you spend a lot of time in the 5000+ RPM range, a bigger carb is just not needed.
     
  11. Pure Insanity

    Pure Insanity 1/2 ton status

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    Re: What\'s a carb spacer for?

    Im afraid I have to disagree w/ you 84. I prefer to have a mech. sec. carb. No suprises. Its only open as much as YOU want. I have run vac. and mechanical and the mech. is more predictable. IMO.

    I currently run a mech. sec. dbl pumper on my rig w/ a 1" 4 hole spacer. Mostly ness. because I run a 50 cc pump on the secondaries. It doesnt clear the intake.

    Yes a vac. sec. is more forgiving, so it is better for someone that is less experienced w/ tuning.
     
  12. CaptCrunch

    CaptCrunch 1/2 ton status

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    Re: What\'s a carb spacer for?

    I have to side with Tim slightly on this one. Most likely the only thing you will see from a carb spacer is a few more ponies up high and some torque loss if anything down low. Even on race cars the spacers are iffy, as they can be a difference of 10 or 15 hp on car and cause a 5 hp loss on another.

    I also have to agree that unless your rig is a mud booger only rig, go with the vac secondaries. Steve is right in that some people like the predictability of a mech secondary carb, but man do they suck gas. A vac secondary carb is the only carb IMO for a vehicle that sees substantial street time.
     
  13. Pure Insanity

    Pure Insanity 1/2 ton status

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    Re: What\'s a carb spacer for?

    They suck up gas? HMMMM. I thot it was the gears, or the 38s, or, or, or, LOL!! Its kinda irrelevant to my application. HEHE!

    On the flip side tho, it only sucks up fuel if Im in it. W/ the mech. the secondaries dont open unless I want them to. I can feel in the pedal when I am at the break over point where they are gonna open. So if I stay under that they wont open regardless of vacuum. So that could save me gas. (as if I cared /forums/images/icons/smile.gif)
     
  14. René

    René 1/2 ton status

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    Re: What\'s a carb spacer for?

    Back again to the Spacer.
    The success of this component has to do with the oscillations of the gas column in the air ducts. At low rpm’s, the amplitudes are long and therefore the way should be long and thin. Thus the gas is very fast and by the inertia, it arrives more gas the combustion chamber
    than the engine would suck in.
    At higher rpm’s the success changes in the opposite. There the Spacer obstructs the gas flow and costs performance. Also a Spacer can’t be universally used, because the efficiency for each engine changes by other components (cam shaft, compression...)

    I hope everyone could understand me
     
  15. Twiz

    Twiz 1/2 ton status

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    Re: What\'s a carb spacer for?

    I think I get it, Rene *add slash-mark above the last e.*

    If I understand correctly,
    A carb spacer's usefullness deppends on the intake-pulse and the intended RPM range.

    With a dual-plane manifold, with-out a spacer, each pulse is divided by the intake manifold divider. A 180 deg. manifold will split the each pulse (1=L, 8=R, 4=L, 3=R, ect..), and pull harder, from one-half of the avalible carb CFM. So, the-end result will be a stronger "pull" from the carb. And that would increase low-RPM vilosity and performance, "Raming" more air/fuel into the chamber at a lower engine speeds

    With the same dual-plane manifold, but in the upper RPM ranges. The split-plenem/split carb-CFM may not be able to suport the needed air/fuel-flow. So a larger carb wouldbe needed, but it's low RPM performance would suffer, due to the higher CFM.

    Now...
    Add a open-spacer. Now each intake-plulse will "see" the full CFM avalibe from the carb. Each pulse will pull from both-sides of the carb. Great for a under-carbed, high output, high-RPM engines. But drivability in the lower RPM ranges might suffer.


    A carb-spacer is a tunning aid, It might work and it might-not. It all depnds on the combnation and intanded use.
    As-Far-As-I-Know, Most After-Market intake manifolds (Elderbrocks- dual-planes) are designd to be used with/out a spacer, some of the single-planes are intanded to be used with a spacer.
     
  16. Slayer

    Slayer 1/2 ton status

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    Re: What\'s a carb spacer for?

    Allow me to add my 2 cents worth.........

    From what I've heard, a carb spacer INCREASES low end torque, and you lose some high-end power.

    The other reason to run a spacer, especially phenolic resin, is to keep the carb cooler, as cooler fuel burns better. In this case, an aluminum spacer would pass the heat along.

    I run a 2 inch phenolic resin spacer, under a Holley 750, on a 383 stroker motor and it did make a difference, especially when trying to carve a line in road rage traffic, while running an aging K5.

    Okay, 2 cents deposited, good luck with your project.
     
  17. René

    René 1/2 ton status

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    Re: What\'s a carb spacer for?

    @Twiztid
    That’s almost exactly which I meant. Two things would be to be still marked. Fresh gas flows into the combustion chamber if the pression before the intake valve is larger than in the chamber (piston goes downward). Normally the gas flow would stop immediately, if the
    Piston is quite down. In this moment the cylinder would be filled to only 65 %. Thus that fresh gas has a mass and because of its speed, it can’t be stopped immediately, so more gas influxes in and increases the proportion to 80-85%. If the amplitude of the oscillation is optimally used (by a Spacer) the proportion can be still increased. If the amplitude fits not exactly (high rpm.s), it develops eddies and the engine loose performance.

    Large channels and trottle bodies have their disadvantage mainly with carburetor engines. The large opening flows the gas with low rpm’s very slowly and has therefore not sufficient strength to “suck” gasoline from the carburetor. Therefore also a large carburetor on a small
    engine needs a large idle jet and a small main jet (in the relation).

    @Slayer,
    The thermal isolation by a spacer is not like that engraving. 0,2in would be enough, as it also were made with almost all cars in Europe. But there is still another advantage: By the spacer also vibrations are absorbed...

    My result: I would install the spacer on a truck.
     
  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: What\'s a carb spacer for?

    Even if you do prefer a mechanical secondary carb, an 800 CFM carburator is not needed for a 454 under 5,000 RPM. Carb sizing is even more important with a mechanical secondary carb, and that's just too big IMO.

    All that crap about turbulence and all that is gimmicks that the people that sell these spacers run to try to get you to buy them. There may be some truth to it, but I'll tell you that it's a fact. Shorter intakes of dual plane design make more low-end torque by increasing velocity. The main difference between a Performer intake and a Performer RPM is the height of where the carb mounts....and 1000 RPM change in operating range.

    This is an instance where bigger is NOT better!!
     
  19. Pure Insanity

    Pure Insanity 1/2 ton status

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    Re: What\'s a carb spacer for?

    I agree that matching components is hugely important. If more people matched parts correctly there would be less problems. I had a 600 Edel. on my motor, It had good off line responce, but when you got a bit down the road, like 100 yards, it would start to fall off. I would barely flutter the pedal, giving it a shot of the Accel. pump, and it would go good for a short distance. Repeat. I never got enuff room to lay it open and stay in it to see if it would do the same on the sec. I was NOT sucking the carb dry, but thats what it felt like. Checked pressures.. flow.. blah blah blah. I bolted on the Holley and havent had the problem. It was just needing more fuel than the Edel. 600 could do for me. The Holley is giving me some problems, due to the age of the carb, but throttle responce, off line and WOT is much better. I need to get a new carb for it, and I will do some major tweaking when I get it. I have some issues that I am not totally happy w/. I NEED another stall converter. Mine got wiped out when the front pump went south. The rig really comes alive at 2500-3000 RPM. You can feel it pull harder, and the whole tone changes. If I can get to 22-2500 stall again I think I would be happier. Plus I wont be trying to drive away at idle. Ahh whoops I have gotten OT. Sorry.
     
  20. twenty_below0

    twenty_below0 1/2 ton status

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    Re: What\'s a carb spacer for?

    So in reading this I cant help but think about the relationship between the intake runners on the heads that will be run with any givin set up, and how they will be a bigger key in the torque issue over the little spacer, small intake runners produce more low RPM torque(160cc), and large runners create high RPM h.p.(200cc),..... is this scientifically correct ?
    In my experience this is the way the old school gear heads looked at it, (whom taught me), but you seem fairly knowledgeable so I thought I would bring this into the equation.
     

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