DO CARB SPACERS REALLY WORK? 4-HOLE VS OPEN (360 MAGNUM-HP & AF-FULL DYNO RESULTS)

DO CARB SPACERS HELP MAKE POWER? WHICH ONE WORKS BEST? CHECK OUT THIS COMPARISON (WITH FULL DYNO RESULTS) BETWEEN A 4-HOLE SPACER VS AN OPEN SPACER ON A 360 DODGE MAGNUM CRATE MOTOR FROM MOPAR PERFORMANCE. EQUIPPED WITH AN M1, DUAL-PLANE, CARBURETED INTAKE, WE COMPARED THE EFFECTIVENESS OF THE 4-HOLE DESIGN TO THE OPEN DESIGN. THE VIDEO INCLUDES CHANGE IN POWER AND AF CURVE. ALSO INCLUDED IN THE VIDEO IS A TUNING TEST-EFFECT OF IGNITION TIMING-GOOD STUFF.

[@coreymulanix9690]

These are the videos I like! Head to head comparisons on dirt cheap parts, something anyone could change in a couple minutes.

[@b.c4066]

Trouble is each engine is different, and these vids can help get in the ballpark, but to maximize YOUR COMBO, you'd have to test it, and without back to back drag strip runs or a chassis Dyno you can easily cost yourself power. What I'm saying is you can't get their results and have it be optimized unless you do the same tuning/testing. Go out and buy a carb spacer thinking it's going to add 10 hp, and in your combo it could cost you 14 hp until you optimize your engines air fuel ratio, timing, etc. And keep in mind these are wot tests with very low coolant temps that are precisely controlled. In your car at operating temp with full exhaust, stock stall converter etc it will most likely behave very different due to the way the engine is loaded on the Dyno vs your car/truck. So don't rush out and buy a four hole spacer thinking you'll gain power and acceleration. The difference between a good engine and a GREAT ENGINE.. is this kind of testing, gathering data, and optimizing the car.

[@heathermiller2917]

@@b.c4066 so good to see someone say exactly what i say! Lol! Ive been at the track and heard the argument that “this spacer added 20hp for my 440, it’ll add 20hp toy your 5.0” I’m like “ummm, that’s necessarily true…”. And the fight is on!

[@b.c4066]

@@heathermiller2917 spent years reading forums, where guys are asking what timing, what jetting. Blah blah blah, put in the work, pay for Dyno time, gather data, learn to read plugs and they'd realize how absurd it is to ask for info like that, even if building a damn near identical engine, sure you can offer a ballpark suggestion, but ultimately THEIR combo will want what it wants. It amazes me that kind of mentality is still alive in this day and age.

[@clintontaylor1345]

These videos are so helpful because not everyone is rich

[@kevkilian]

I love that the magnum is getting some love, and wow, the afr is crazy interesting!

[@tonyovermyer5368]

I'm not even a dodge guy but I do too! Gives some options for guys who want to do something other than an LS in a classic Mopar without spending lots of money

[@The4x4manonbroke]

Yeah I have a Durango and been looking into building a new 5.9 magn

[@broc2238]

I’m eating up these magnum videos. Building a drag week truck and planning to stick with the magnum that came with it. Not a ton of stuff out there so loving all the attention you’re currently giving it 😁👍🏻

[@RebeldryversGarage]

From personal experience, I went from an RPM intake to a Victor Jr on a 400 HP 383. 9.8:1 compression, 236/242 hyd roller, Victor heads. The loss of low end torque was noticeable. On a suggestion, I tried a 1 inch 4 hole spacer to get some low end torque back. It did help, but should have left the RPM intake for what I was doing. The four hole spacer helped with carb signal.

[@r.d.riddle2068]

This whole series is great. I keep going back to the tuning myths we had 45-50 years ago, and now it makes much more sense why some things worked and many didn't. Keep up the good work. PS: If we only would have had the heads back then that are available now........

[@brentonk461]

I'm not surprised about the jump in power from where you had the timing set, and shifting it to where I said. I didn't even have to get out of my chair.

[@karlsracing8422]

Love the Mopar content!

[@440phoenix]

Thanks Richard for the Mopar videos, 5.9 magnum, and 440. All the Mopar folks are very happy I'm sure! We gotta get you a 440 to Big Bang! LETS MAKE SOME NOISE!

[@stevenshepherd1905]

The torque curve on these engines makes you run them at part throttle to keep the revs down in the power range. I noticed it dropped 100 ft lbs above 4K rpms.

[@angelsanchez3074]

Man you are the best with this video i ran an open spacer on my 302. I will take your advice because down low is where i want my power. Thank you for doing this test

[@moparnut6286]

The best engine videos on KZbin period!! Loving the mopar content!

[@scotttimpany2845]

Neat comparison on JUST a one inch carb spacer. Significant difference.

[@dantupper1784]

Thank You, Richard for the Magnum Series!. Too bad the M1 dual-plane intake had such a limited production run. They were around $300 each back in 2006. The water heated intake makes for good driving in cold weather- some vehicles are more fun when the snow starts flying. When these M1 dual -planes sells used for 2X what they cost new here is definitely interest. A Edelbrock Performer or Performer RPM for Magnum would be easy-borrow from the Magnum AirGap the intake to head section to bolt to the Magnum heads. The 5.9 Magnum had a production run of almost 20 years, millions made, going to scrap. All for the want of a bolt-on Performer, Action Plus, or Contender intake. Glad to see the Magnum get some attention. Go make some Magnum noise!!

[@blueduster74]

Love mine on my Ramcharger. Thing runs so good I’m hesitant to put efi on it.

[@dantupper1784]

@@blueduster74 Another year later.... No Change on the manifolds. Ma Mopar's last two owner groups come from non-hot rodding cultures. Ramcharger's are always fun.

[@rokguitarstar]

Thanks to your video I chose the 4 hole over the open spacer!

[@david929190]

Yes! This is what I have always wanted good data on!

[@mob_slaya1866]

Recently I have built my sbc [40 over 4 bolt 350 with custom grind 488/488 roller conv cam,906 heads and a holley 750dp sitting on edelbrock air gap] and I had installed a 1 inch open spacer. I soon realized there was a noticeable negative power difference and after watching this I have a 1" 4 hole spacer and 1/4" phenolic spacer on the way. I hope to see improvements...

[@JC-gw3yo]

Surprising. Great knowledge and numbers don't lie.. open spacers have been a gimmick for years

[@cjbert6790]

Every engine is different. I put a 1 inch open spacer on a basically stock 383 roadrunner engine with a Holley vacuum secondary 780 carburetor and gave a tremendous seat of the pants boost!

[@blainesnider9089]

Thank you for showing the timing deal so that guy could 👀

[@WildAzzRacing]

Would liked to have seen a two hole spacer. Basically an open hole with a divider to keep the dual plane intake properties but with more plenum volume.

[@adamtrombino106]

4 hole beats an open design, WITH THAT PARTICULAR carb and intake. I would like to see the results when using an AFB or AVS in the 750cfm range. My 30 over 9.0 to 1 360 with a MP 450/455 cam and now Edelbrock spread bore dual plane instead of an M1, consistently made 8 hp and 14 lb ft more with an open spacer, than just sitting on the manifold. It made an average of 6 more hp with the 4 hole but only 5 lb ft, (that had to be mildly machined to accept the secondaries), over just the carb on manifold. Timing was using an MSD set at 34* at 2800, no vac adv. I will say this. The AFB did need some jetting and rod tuning because out of the box, it was lean down low, but way rich WOT. The AVS was better at low and mid range, but still rich WOT. Anyways enjoy your vids!!

[@Packer1290]

Interesting but one big data point missing. Results w/No spacer! I heard the part that the carb wouldn't fit without one, but it would have really interesting to see if it would have fell between the two in terms of power or who knows, maybe it would of had the best power of all.

[@6spd85notch]

Thanks I’m going to order a 4 hole for my 347 with 750dp and air gap. Cool video. Simple and effective.

[@brokentoolgarage]

Good stuff! I have always preferred 4 hole spacers, but never really tested it.

[@thman6453]

Great video I actually figured out some of the problems that I might be having from a carb spacer thanks Richard 👍

[@zandemen]

What this test shows me, which I suspected from the start, is that if you change your intake manifold, spacers or otherwise adjust the signal to your carburetor, you have to tune your carburetor. After the swap to open spacer, tune your carb to work properly with that setup and run the test again. Then I'll say you changed the carb settings and that caused the difference, lol.

[@zandemen]

BTW I'm about to flash up a fresh rebuilt 383 and tuned my edelbrock a little rich on the single plane intake, so your video is making me think that was a good choice in calibration of the jets and rods.

[@besearchingforwisdom6267]

Run 2 or 3 inches of the 4 hole spacers until you have maximum effect. Keep going with your videos 👍

[@johnshoffit2541]

I love the intro music

[@cfmechanic]

I use a spacer under my sniper 2 reasons. 1 to help keep sniper throttle body cooler, 2 to increase plenum length, with the holley sniper it needs to be 4 hole it whistles with open spacer

[@madmod]

I bought phenolic resin blanks for making adapters, spacers, and heat barriers for all sorts of stuff. Its cheap to find and make a nice piece.

[@madmod]

-Side note. You are such a hype man. Got me "wooooooooooo'ing" for a Dodge Magnum lol

[@TheBukesde]

A really interesting test!

[@danvye88]

I love that the old Dodge engines are getting some attention, thanks Richard! Have you ever done an intake test of Vintage intakes? Like the old Eddy Tarantula manifolds?

[@gregleenyit]

Richard this thing needs more cow bell !

[@larryhutchens7593]

Open spacer? Carb to open spacer then open spacer to 4 hole (4 hole to open then back to 4 hole). Turbulence possibly? I always thought that the open spacers worked best with single plane intakes but I could be wrong. Note the torque curve: Max torque is exactly where you need it in a pick-em-up or heavy van that might be pulling a load. Possible that the MoPar engineers designed it that way for a reason? I had a 98 Ram 1500, 5.2, 5 speed, 3.23 gears and it would pull an all steel car hauler with a Duster on it just fine in 4th gear. Cruise at 65 all day with cruise set.

[@michaelstansfield319]

Excellent video, short, sweet, and to the point. My experience, back in the day, was that 4-hole spacers were best for street applications and could actually improve low RPM throttle response. Open spacers were good for high RPM race applications.

[@speedracer412]

Should have tried a HVH spacer (tapered one) great video tho

[@adamdeskins5888]

Please do more magnum test love it

[@richardp6178]

Thank you for this! I usually use phenolic or resin spacers and fuel return system on carbs to try and keep the carb and fuel temps low. We all know that carbs hate modern fuel and the cooler we can keep them the better the engine will start.

[@Bige4u]

Just out of curiousity, it would have been nice to see what the AF ratio was with carb to intake before the 4hole and open hole spacer was added.... either way, i see there will be a slight leaner mixture because of the simulated added intake plenum that the spacer provides, allowing more air without a change in fuel delivery.

[@russelljackson7034]

Right on

[@0johnny082]

i feel like running them stacked with the four hole spacer on top of the open spacer would be good

[@SARJENT.]

Kool vid. I'd like to see that same test on a single plane manifold.

[@bdhd206]

Fantastic video and education. Thanks!

[@jimkillen1065]

i appreciate your videos . Thanks for all you do

[@jesseduke694]

I like that your showing what happens to the air/fuel ratio. Very interesting to me.

[@MrStrollerisme]

Cool. Exactly why I never use open spacers, don't like them. As to lean n rich? Me old school and I just don't do a high smooth idle adjustment with a 50 rpm lean drop and happy engine, happy carb.

[@Linwood_Garage]

When they did this test on Engine Masters it did the opposite. The open made more power on the dual plane. But that engine was more powerful also so I guess it's a case by case basis. 🤷🏾‍♂️🤷🏾‍♂️🤷🏾‍♂️

[@billalderman4065]

I believe a 4 hole makes more power on a open plenium and a open spacer makes more on a dual plenium, Just haven't seen the proof but it feels it lol

[@Impactjunky]

Just a couple days ago I posted a vid about putting a four hole phenolic spacer on my friends 76 D100 318 with the stock cam advanced 4 degrees, an Edelbrock SP2P low RPM torque intake for heavy vehicles and a Qjet. The four hole spacer severely outperformed the open 1/4 inch gasket we had before hand. Without the four hole it would only leave about a foot of rubber and slowly accelerate away but with the 4 hole installed it leaves several feet of rubber and accelerates much more aggressively.

[@jrdmotorsports9718]

That's what they do. More signal at the carb, better it pulls fuel=more torque.

[@Impactjunky]

@@jrdmotorsports9718 They also split the carb in half only letting each individual cylinder see half the CFM it would see.This can be good or bad depending on the specific application. I tried a 4 hole spacer on my solid lift 235 HP 273 thinking I'd gain some much needed torque to get through the low RPM bog of my 2.76 gears and it did help a little bit down low, but it hurt so bad up top that I swapped back to open after one drive. Funny how some engines completely defy your expectations.

[@jrdmotorsports9718]

@@Impactjunky It's ALL application specific. They are tuning aids. The magic isn't from the spacer, but what the spacer is doing for the combination, and how it is affecting the manifold. Put a 1" open on the manifold, and put the 1" 4 hole on top of it. Watch what happens.

[@Impactjunky]

@@jrdmotorsports9718 I've heard a 4 hole on top of an open spacer makes really good power, seems like we may have been reading the same article or at least a similar one. I wish I still had that little 273 around to experiment with but I tossed it out for a cammed, carb swapped 6000 RPM 5.9 Magnum years ago. Getting ready to see if the Magnum likes a 4 hole tapered spacer as a compromise for a 4 hole on top of an open because my velocity stack/air cleaner combo doesn't offer me any extra hood clearance.

[@jrdmotorsports9718]

@@Impactjunky It's not from any article bud, 35 years in the business, and have tested my fair share... on the dyno, and on the track. Back when HVHs weren't even around I used to make my own spacers, and combined different styles. I know what they do and why. In your application, feeling it lose top end says it needs plenum volume, hence why the open works. Putting a 4 hole on that will help bottom end without sacrificing top end. The reason why you lost top end with just a 4 hole, is due to the plenum volume being too small. All they do is help tune a manifold.

[@robertkeime4907]

Great video

[@MichaelKegg]

It would be nice to see you repeat the test, with an open plenum manifold.

[@scotttimpany2845]

Carb linkage plate with 4 holes, instead of open plate, might show a measurable gain...

[@dbrandon4528]

Yes they do

[@soggymanturtle]

You’re the man! Keep it up.

[@Ecosse57]

very informative, thanks!

[@Arthagnou]

another interesting test idea...compare carbs with metal intakes, Carb +Space+Metal intake, Carb and Plastic intake. Isolating the carb from the engine heat would seem to be a benifit, while a carb spacer does help, the bolts holding the carb to the metal intake does cause a heat transfer. It would be interesting to see if there was any gain with the full plastic intake.

[@richardholdener1727]

carb isolators do very little (other than act as spacers), which can change power (from a chnage in carb signal) depending on the intake used. the change is not from temperature

[@MossTheJockey]

Thank you!

[@mikie9077]

i would like to see a tapered spacer test.

[@madmodsgarage1179]

great and informative content as always 🤘 However, please try to work on focus fluctuation when you film the computer screen, gets dizzy after watching the graphs closely :) thanks in advance ;)

[@davidwilder7109]

Only reason I have a spacer is so I can clear the egr on the factory intake with a Holley.

[@RonaldReed-ul9du]

Whats up Ricky, i know this is old but thought id rewatch these on the Dodge Magnums because im going to add some HP to one in my retired work Truck, i plan to port match and some bowl work, blend the valve guides because im too cheap to buy decent heads. I appreciate the data you provide. Hey ive adked before but forgot what you said, do you tune? Hahaha

[@oscarwalton1188]

I'm curious if the open spacer would do better with a more agressive cam shaft

[@jeffjohnon4223]

No, 4-hole or directly on the intake. Radical cams with lots of overlap love the extra carb signal, especially if you have a carb with annular boosters, they can be worth close to 100 ft/lbs down low.

[@440phoenix]

2" spacer next?

Always great!!!

[@tomrose6292]

Richard , I had the opposite results from a sbc 350. The 4 hole on my stock silverado gen 1 motor and a boat anchor cast iron intake. And it lost a BUNCH of everystuff...then the open one I really couldn't tell the difference in that and no spacer.

[@fuelbasti]

...and what is about this dual Edelbrock spacer which is waiting for installation of my chevy performer manifold 😧

[@petergauthier5074]

Try recurving timing and blocking heat cross over

[@grantellis3046]

I think that if you removed the material between two of the four holes you would continue with the duel plane manifold

[@kylehoover702]

I’d like to see them stacked

[@hugieflhr03]

That was interesting!

[@Amack1964]

Would it be possible to put the part numbers in the description so we can source them if we want

[@totensiebush]

Something I don't think you have: a comparison in powerband between big cam/stock heads, mild/mild, stock cam/big heads, all making around the same power. Is the powerband better at the same power level with the big heads/stock(ish) cam?

[@richardholdener1727]

BIG HEAD MILD CAM IS LS

[@jeffcolt9185]

Wanna see same video, but on a SBC or BBC

[@MDAdams72668]

why did you not fatten the carb up for the open spacer ??

[@bobdimartino6738]

but how did the engine do without the spacer?

[@NoStringsAttached777]

I really would like to know what applications the headers were designed for. Reason being is that it would have been much easier to build the header shown if the destinations on the collector had been swapped for the front and rear positions on the mounting flange.

[@fortnoxz71]

Interesting.. what if you put bigger jets on the open spacer? Maybe more power on the top end? Now I’m wandering if freiberger was using a rich carb for his test and that’s why he showed more power with his test… using a open spacer and milling his intake.

[@cjbert6790]

Those engines were originally rated at 300 horsepower, so it’s not far off the mark.

[@roybruce9844]

Why 1/2? Do you think there would be any advantage if you had hood clearance for a 1 inch, or 2 inch, what point would be negative return?

[@devillockj]

I’ve had great results with 4 hole spacers on small cubic inch short stroke motors. Open spacers seem better on larger cubic inch. Application depending.

[@jrdmotorsports9718]

It all depends on manifold. 4 holes create better signal and more low end torque on big plenum intakes, which helps on smaller inch engines. Open increases plenum volume which does the opposite, but helps with bigger engines that need more plenum volume. Spacers just tune the intake. That is all.

[@ragtopdlxzl1]

This question is a bit off but .... ZL1 Lid spacer for a Eaton 1.9, I have the convertible so fitting would be close does this increase volume enough to make a difference? Then there are spray connections....hmmmm

[@shannonschneider8413]

You haven't done any aussie V8s yet

[@richardholdener1727]

NO SIR

[@shannonschneider8413]

@@richardholdener1727 you know it needs to be done,but trying to find,then send over would take forever,or when the covid finally goes,come to Australia and get all the latest info and updates from aussie websites,and cheers from australia

[@kelseyschoenbaum4681]

Can't wait for kegger intake mods. Is reducing the plenum volume in the keg bennificial?

[@davej3487]

UTAwesome performances has done some of this. They have a 'Tech' page.

[@kelseyschoenbaum4681]

@@davej3487 yeah been there, read all about it, bought a set a while back. I know Marty has put a ton of research into them but i'm wanting to see Richard test them.

[@MalteseCross]

So spacers not worth it... especially if you're worried about clearance under the hood

[@extremeoutdoors9068]

Have you tested a tapered spacer. If not I would love to see the results.

[@jeremypike9153]

I'd like to see this done with a single plane intake manifold same engine same carb. Let's see the Dyno numbers and the afr

[@richardholdener1727]

DON'T THINK THEY WOULD BE HAPPY TOGETHER

[@dynodon100]

I have always run 32-35 total in all my LA's Why the pulsing on the videos of the grafs ? I will be starting a 416 build in a few months as the kit has arrived .

[@erikturner5073]

Honestly I shake my head when I see people put open spacers on dual plane intakes.

[@dsrdoof1258]

What Carb Spacer should I run?

[@erikturner5073]

@@dsrdoof1258 details are needed. What setup do you have, engine combo, intake, and is it a street or track (car or truck). Just asking what spacer you should without details is a broad question that can't be answered correctly.

[@vincentbrugetti7254]

@@dsrdoof1258 the four hole kind, if u have a dual plane intake

[@dsrdoof1258]

1969 Chevy C10 5.7 350

[@dsrdoof1258]

I daily my truck

[@archivegarage7638]

Spacers make more power because it helps the high-speed air coming through carb to change direction towards the ports instead of ramming it at intake floor, it's all about how air flows. Too bad this combo couldn't be tested without a spacer. Also the intake divider wall on this combo should be thinned a smidge so there's no flat steps for air to stagnate on 5:19

[@richardholdener1727]

SPACERS WON'T CHANNEL AIR TO THE RUNNERS

[@archivegarage7638]

@@richardholdener1727 The 4-hole had larger diameter holes than the Carb, which helped average out to a diffuser for the base of carb, allowing air to be pulled to intake runners easier, test it Richard!

[@richardholdener1727]

HAVING TESTED SPEACERS MANY TIMES-MY CONTENTION IS ONE OF DIVERTING THE AIRFLOW

[@archivegarage7638]

@Richard Holdener I didn't say or mean it diverted the air. I said it helps and allows the air to flow easier. Could be a great episode, big spacer test getting at the science of it

[@gagemosley8365]

can you please test the difrence in power after adding total seal piston rings in a na ls?

[@obbyjep7597]

Practical test, probley relates to a lot of street drivin engines

[@donaldpowers3314]

It would be cool to lift the dual plane and put the 4bbl M1 AND TEST THAT against the dual plane... none the less smother informative video thanks... so everyone go hit the LIKE BUTTON!

[@donaldpowers3314]

@Daniel G mopar M1 air gap... I have 2 one 2bbl and one 4bbl..

[@donaldpowers3314]

@Daniel G thanks.. none on any running motors. I did pick up 5 mph with the 2 bbl. With just that switch on 245k 96 ram 1500 in a 94 dakota... itran a 13:42 at 99mph. But I do have a 408 waiting to go in somthimg.. I'll check into the Huges thimg you mention. And I've acquired his throttle body.. Was looking into buying some aluminum SBM heads but still looking

[@donaldpowers3314]

@Daniel G I googled IMM The other day... I'm down Houston way

[@brendanbelli8769]

OK so I just watched Eric weingartner Do the same test and have the opposite results so now I’m confused what are you guys doing to me?

[@richardholdener1727]

spacers are not universal-they don't do the same thing on every combination

[@michaelgiglio1571]

Richard. Would you use a open spacer with a singlepplane.

[@frankpittman9049]

What would a say 2” 4 hole spacer do on a single plane intake

[@richardholdener1727]

might help carb signal, but single plane would still act like a single plane

[@matthewcalifana488]

Dual plane Open spacer , Signal plane Four hole spacer .

[@TheScrotus]

Since this is about spacers. What was the difference with and without them. The actual topic. Not between the 2 spacers or in depth about what timing did. Not actually the topic.

[@kcermit1]

What I am seeing is the open spacer did made the motor more efficient in that it lost a small amount of power and torq but ran on quite a bit less fuel. If you had put in bigger jets wouldn't it most likely brought the torq/hp figures up?

[@richardholdener1727]

incorrect assumption-the signal changed making the motor less efficient

[@kcermit1]

@@richardholdener1727 Am I miss reading the graph - with spacer , roughly it was down .03 in torque and hp but was using .9 less fuel. I guess I don't understand how that relates to signal, bigger jets would not have helped that lean condition while increasing P&T?

[@Bikedueder]

Why does EVERY article, video, or whatever, always have either a four hole spacer or an open? There is an an entire industry of two hole spacers, including Edelbrock. NO ONE EVER tests those, ever...

[@richardholdener1727]

The two oval holes? Westech has those

[@approachingtarget.4503]

4 whole worked, open didnt. Your pals at motor trend showed removing 1" of the divider was worth a power gain. Curious what your thoughts are about that. And with a dual plane. Each side of the carb is only shared with 4 cylinders. 1 primary and one secondary. With a double pumper with 72/74 jet balance. Does it equal out to a 73 jet average? There just seems more to this then these simple results. I believe a low profile single plane with a 4 whole tapper spacer would yield the same results! I believe the open spacer disturbed the signal at the base of the carb. Also the reason the A/f was leaner.

[@richardholdener1727]

THEY TESTED ON A DIFFERENT COMBINATION-SPACERS AND MODS ARE NOT UNIVERSAL

[@amyhepker9025]

You seem to be the expert on Induction. Please tell me if you can use a Carburetor setup with Fuel injection? Will the fuel injection take away lean spots in a carb system? Working via the Co2 sensors????

[@richardholdener1727]

YOU CAN RUN BOTH