Spacers are another example of people wanting to take a advertising based - word of mouth approach to engine development, rather then realizing each combination is unique, especially, at higher levels, and not wanting to acknowledge the amount of “homework”, you’re providing, to provide guidance, not nonexistent canned answers, here. Thanks for sharing your hard earned and honest experience.

I can't wait to see these results. I'm running a 1-inch open spacer on my 496.

Perfect, Monday morning tech video

I had one of those tappered HVH super suckers on a mild 340 with an LD340 intake and make a bunch of changes to the carb. It leaned it out a ton. I later tried it on a much hotter solid cammed 340 with a victor intake. It gained 10hp at the top end. Made 480hp at 6900rpms.

Long, long time ago, when question came up, would make a spacer out of wood, spacers were rare, quick way to validate purchase. Didn't have fancy shapes back then.

I've got a stock boss 302 engine. Added a 2 inch four hole spacer. Improved off idle drivability. Got lucky.

If you want to have some fun Eric. If your dyno headers have 3 bolt flanges and are 3" and have pipe after the collectors. Insert a 3"×2" Collector adapter with 10 inches of 2" exhaust tubing on it.. this creates anti reversion after the collector. Lowers the pressure in the collector and primary tubes. The slight reduction thru the tube speeds up the exhaust flow increasing scavenging effect. Any reflections coming back upstream can't go thru the middle of the tube. But can go around it into the tapered area at the collector flange. Warning you must carefully monitor air fuel ratio stepping up the rpms 200 at a time. Cyclone headers made some A/R headers for 440-3 motorhomes. The motorhomes got 33mpg but melted the pistons . They could not release them do to liability issues . Who knows which reducer diameter and length will work best. Wont be expensive to experiment with. I talked to a neighbor who owned 360 and 410 sprint cars. He loved and understood the idea. But there was no place to put them. Then he showed me the many sets of headers his engine guy had dyno tested the set that made the best power at race rpms had stepped primary tubes. But stepped down. Bigger at the port and smaller at the collector. This sped up the exhaust flow again creating additional scavenging.

Thanks for the tech info Eric really appreciate the hard work and showing the results

seeing a dyno test of the 292 compared to the 195 afr and trick flo and other heads on a 350 would be interesting

Yes good to see results again. I recall a 440 big block drag challenger using holley street dominator Ported with Conversion 2 inch spacer for a Dominator 1050, back in the 1990s it was 10.0 car.

Real good comparison. Cheers😊

Thank for sharing your knowledge and time,finally providing dyno Spacer Results!! Myths!!😊

I'm using HVH 2" 4 hole spacer on a Air Gap 468 BBC i don't have it running yet but I believe will work for my street build,hope to test it soon at the track, I'll make passes with and with out the spacer but really its to keep my 950 carb cool 😎 😊😊😊

Super info! Great video.

Great content. I wonder how these would work for a dual plain intake that doesn't have the cut out in it

Thank you for your knowledge and video's USA 🇺🇸

I'm more curious about spacers vs no spacer than comparing one spacer to another. Maybe you have another video where you do that.

Awesome testing!

Which spacer would be best for a 350 CID with a 4160 Edlebrock Carb and RPM Air Gap Performer?

Just had my Holden torana on the dyno , 304ci , high rise dual plane and it made +10hp with tapered 4 hole , the power came on sooner also .

Hay guy love ur vids.i have a 327 flat tops.is a 1500 to 7000 split plane intake good for it?thanks

What if you put a 4 hole spacer on a 4 hole intake such as the brodix hp-1 intake???

Eric: Thanks for the info. I've had similar experiences with spacers as well. I found in most cases with the same tune on the carburetor, timing and spark plugs that the fuel ratio was a little richer. This might explain the lower horsepower numbers using a dual plane intake. Seriously though, I try to run and intake/carburetor combination only, because of the turbulence factors with the mixing of fuel. I may also experience vacuum leaks. In essence, the carburetor/intake combination makes this simpler. The old adage is to "KISS" or Keep It Simple Stupid, ya know?

Have you tested any spacers for spread bores? Are has anyone used any that has worked for you? I only see them for straight bores.

Honestly, in my experience mostly on the street with pump gas.The biggest benefit to the spacers I chose to run, is the insulating effect. Keeps corn fuel from boiling. Especially in a Quadrajet equipped big block Chevy with a factory cast iron intake. I've found the 3/4"inch Corvette style spreadbore spacer made from plywood laminate to work the best for a Quadrajet.

great Viedeo ! I am interested what the HVH tapered with divider would do on an dual plane with not cut divider. I am planning to use a 4150 fuel injected holley on a dual plane. Maybe I'll try to use an open spacer below the tapered to get the benefits of the tapered to my throttle body AND the open desing to get the compensation to the dual plane ?? I think I'll make some dynos.

I was wanting know if the dimpled spacer really makes 20 hp . there is a video on 408 SBC that made 21 I find it hard to believe. if it came from you I would get one. Im sure you can watch it thanks for all the great testing.

You should try flipping over the lower plate on the 2 peice Reher Morrison spacer just to see if it makes a difference

how about the dimpled polymer racing spacer?

I am reading/seeing some spacer claims for a 604 chevy crate for dirt racing saying to get better low/mid torque, run a spacer (1 inch maxis common for rules), but mill off a half inch around the base so that the taperes fit down into the manifold a half inch. So far, I have not seen any tests verifying this...Anyone know of any? Thanx

I'm running an NA big block Mopar with dual quad tunnel ram. I saw improved fuel distribution when switching from open spacers to the HVH tapered spacers, according to my spark plugs. No changes in ET at the track, though!

What is the thickness of each spacer. And what is the surface area of the top vs bottom of each spacer?

The gain on the hvh adapter, was the gain partly because of a dominator carb and the spacer or just the adapter? So my question is if there is a 8 hp gain from the hvh spacer, then possible another 10-20 hp with a dominator vs a 4150 carb one could potentially gain almost 30 hp?

Nice that's awesome testing

Glad I put open spacer on my dual plane 😂

Did you do a base test with no spacer ?

Truth is, a spacer must be designed specifically for your engine combo. Some people get lucky and pick up ft/lb & hp.. However most don't.

No spacer is one fits all for sure. Having tested and or been present during, I have seen -15 to +15 they can be cheap HP or an expensive failure. I believe they are just a crutch for the wrong choice for intake

Thank you for posting this video, I have a 502 that I shaved the heads down .030”with a Weiand Track Warrior single plane that has been shaved down and port matched. I am going to upsize my carb from 4150 to 4500 1050cfm Dominator and thanks to your video I feel that I can keep my same intake a use the adapter spacer. Was that spacer 1”?

Do they work on TBI's Eric ?

Be ridiculous, put a dominator on a dual plane.

I ran a 2" spacer under a Predator carb on a big block Pontiac back in the 80's. I found the Predator ran best the further it was from the valves. I always had issues with local mechanics as they hated the existence of spacers. None of them understood the fuel I was running. The dual plane intake has to be the worst design I have worked with. When you have to retard your timing to be sure the spark doesn't occur until the piston is heading back down should tell the ones that know what I was doing. But if you don't know, it is time to get out of your tiny world and hang out in the big boy section at the drag strip. I have wondered if turbo boost would work better if the inlet to the intake manifold was below the carb. This would create better vacuum. But I prefer replacing the Teflon wipers.

Hey Eric, great video we greatly appreciate you sharing your knowledge. I wanted to ask a question. I have a 93 c4 corvette that I picked up for cheap. It has lt1 with a healthy cam and cnc ported lt4 heads. It was designed as a drag car but I am currently converting to an autocross car.. Do you think it would be beneficial for me to switch to a dual plane or keep the Victor Jr and have it ported? Thanks p.s. it has a holley 830 carb.

I have a Wilson 004110 4 hole tapered 1” spacer. The space in between 2 of the 4 holes is cut out deeper than the other 2, all are tapered and radiused. Do the larger cut outs get orientated with the barrels of the carb, front 2 and rear 2 . Then the 2 smaller cut outs would be front to back, 2 barrel to 4 barrel. Does it even matter? Very confused and hard to explain but when you look at it easy to see the difference.

I've had the wood open spacer for years on my big block Chrysler ( originally bought for my 440 to stop heat transfer from intake to carb ) now on my 493 I bought the AFR spacer recently from AFR ( the first person I talked to said they had it in stock and that it would ship right away LOL ) took three weeks . Now that I seen this video I'm questioning my purchase LOL

off the subject of the video. you see dart is offering the new SHP heads for ford windsors in 175cc and 205CC 62 and 58cc chamber about 580.00 u un assembled and 850.00 assembled any tests coming on those? i know you said you stopped buying dart chevy heads when they got more pricey

Eric, love the videos. Here's a thought about the booklet you're selling...maybe you already discussed this but instead of spending the time and money to have them printed, just make a link on your website for people to purchase and download a PDF version. That way, as you add things to it, people can go back in with a code and update their PDF. This way you'll probably be able to sell more books because you can adjust the price since there will be no printing and binding costs.

Hi Eric. Great videos and thanks for taking the time to post them. Here's one on a current build I'm doing. Just curious what your thoughts are. 572 hemi. 12:1 comp. 660 lift solid roller. 265/270'ish duration. 110 LSA. Stage V heads from For Hemi's Only. Any other hemi I built has been dual carbs. This one will be the Arlen Vanke dual plane single carb intake with a 1050 dominator. That said....I did machine down and hand shaped the divider just like yours in the video. I have a Wilson 4 hole tapered spacer. I think it's 1.5" tall? On this application do you think the spacer will benefit? Or waste of time? Jet up or down with spacer? Motor should make 750/700 hp/tq. Going on the dyno soon. Thanks.

I wonder if plenum volume could be different on a static pull compared to how the engine is pulled down at the shift points on the strip. Could the Dyno show a power increase that you might not see at the track.?.

Wilson makes the best spacers hands down 2" tapper makes more than any other

Funny thing, the tapered spacer only lost 5 hp on my tunnel ram big block mopar. I just wanted to see what would happen between tests

Eric, I'm using a Pontiac victor 4500 with the open 4500/4150 open adapter. Like the one you pictured. I'm running a 830 4150 on it. How much power do you think it kills?

You should try hamburgers spacer part number 3210 , 4 hole tapred to 2 hole designed for dual plane manifolds

Thanks for the work! How does the spacers affect drivability in the part throttle ranges? Does it affect the signal to carburetor in part throttle or tip in on the street? More pronounced with straight boosters over down leg boosters? I know you didn’t test this on the street, maybe you have talked to someone or someone will chime in with actually testing at part throttle/tip in. Thanks for all your work dude 🤘

That open oin, #1, is phenolic, not wood. If I recall correctly, it's layers of canvass and epoxy resin.

When do you plan on putting a larger camshaft in this engine. I feel it’s holding this engine combo back a little .

Super interesting.

Hey Eric so my dad wants to ask in a 2 barrel HVH adapter the one that is adjustable forward and back to see which position makes the most power forward, center, or backwards. And the sideways ones to. Now my racing season is almost over 1 got 1 more race left so after 1 more race I should be able to contact you soon about sending my heads to you and ordering a intake manifold for you to port so by that time we can order those spacers threw you to and have you test the spacers if that is ok. Just a thought my dad had.

I knew a guy who got 150 more horsepower from a 1/2 inch spacer. Yeah, it had a nitrous nozzle inside it though. Enjoy your videos even though i don't have a hot rod anymore. I watch because i might get another hot rod.

Right on

when you go from a 4150 carb and spacer to a 4500 carb and adapter/spacer, how do you know it's the spacer and not the carb that gave you the increase?

Interesting that you say no spacer is worth 20hp. A friend went from 13 teen et's to 12.65 by adding a cheap 2" open spacer, no other changes. I'd guess he was pig rich without the spacer and the spacer got him to a much nicer AFR, but but half a second in et has to be more than 20hp 😂

Options vary all the graphics and printed bs you want doesn't change history tunnel rams blowers high rise intakes all have a place in racing development spacers give you more top end more gas more air

I know this is late after you made this video. By the way, it’s very good. I was curious as to what was the hp without any of the spacers ? Just to see what performance these spacers actually provide. Thanks. 👍

What about EFI? I guess these Results are not comparable(you said Carburated engins)....i run a tapered 4 Hole Spacer like the AFR on a DUAL Plane (Edelbrock RPM), on a SBF (393), and it made the most Torque and Power with it !...... The Performer RPM has also been modified by myself, (milled the Divider down 1/2") and as mentioned running on top of that a 1" Spacer , 4 Hole , tapered Phenolic.... Me and the engine likes it !

Do the spacers effect the air-fuel ratio

I wonder how that 4500 to 4150 spacer would have compared to running a dominator on a 4500 manifold with a plain 4 hole spacer.

So What spaced is the best for my bb 454 mark iv dual plane weiand stealth intake? This motor is a 496 stroker build.

I tested that . Greatest tag . Along with’ I ain’t no super man’ Two great tag lines. By the way ‘ ain’t ‘ is not a word used in Australia, at all , ever. It’s “ am not “. Just a little cultural difference 😉

In practical terms I've both witnessed an open spacer making a few HP on an RPM Airgap BBC, but once in the vehicle it was abysmal, and swapping back to a 4 hole spacer made the vehicle much more responsive/drivable. Your results may vary.

Of course you don’t have the 2” 4150 HVH that I have. My luck strikes again! Lol

I use a spacer for heat soak, Not horsepower gain. We all want a little more horsepower, but I am not believing a stupid spacer is the answer. wth

Dominator??? Hmm?? On a street 496??? Bigger IS BETTER!!!!!!

I've seen several bbc gain 30 to 50hp with a spacer, so that is inaccurate information. I've also seen Allstars spacers cost 20hp.

Spacers are for heat soak manifold to carb