The market has several companies that offer a "super sucker" style spacer. [APD, High Velocity Heads, BLP, [others]. I usually install one because "they say." it helps. Yet, I have never conducted a valid back-to-back test.

The question is, has anyone conducted a valid test and has any results to share the difference between a 2" open spacer?

The engine;
*SBC 383,
*high compression,
*roller cam,
*Dragon Slayer heads,
*open plenum cast intake
*APD methanol fuel system
*S-10 that will weigh about 2750 with driver
*powerglide w/6300 range converter
*expected et 6.20 range

The guys on Engine Masters (TV show) performed the comparisons you are asking about. You may be able to find that show on the internet.

The Engine Masters show you need to watch is "Carb Spacers: Gimmick or Gold?" It first aired on April 17,2020, Season 5-Episode 8.

Open spacer if you need more plenum volume.
4-hole spacer for a taller mixture column, or to build velocity, discourage reversion, or help a carb that might be slightly too large.
Super Sucker vs. 4-hole would be the question you're asking.
An almost impossible task to clearly determine which is best in a certain car, in certain conditions, on track.

"Your mileage may vary."

I'm running a vintage, drop leg booster Holley 850 with a BLP products 3/4" spacer that is sandwiched between the main body and baseplate. 2 more 1" spacers under it, both are 4-hole I think, but now I'd have to go look.
On a Victor Jr. 2775
383 SBC

But too answer your question directly, who knows?
Report back with your findings.

This message has been edited. Last edited by: Goob,

I have been using a 2 inch tall open spaced for the past four years on a modified, (welded) Edelbrock single plane 2927 intake. I have two Dominators, one is a 3 circuit 1050 that The Carb Shop modified, the second is a 3 circuit APD Max Flow 1250. In both cases the open spacer made more power, (the mph increased).

Presently I'm using the Carb Shop 1050 for bracket racing but when I run the car in Super Gas or Super Comp I use the APD 1250.

Years ago I used a stock Weiand dominator base intake with the spacer on a smaller 468 it didn't help until I welded four "Whale tails" in the plenum, that made a huge difference with a little stagger jetting.

Bob

Did I miss something? Did they fuel each spacer? High speeds/ jet and timing? Dual plane loves stagger.

This message has been edited. Last edited by: BP758,

I see little to no difference on either of my small blocks going from 2in super sucker to #1 stop throttle stop to 2in open spacer. Gas or alcohol

ep

Spacers are try and see if they help. If they do it's because they add plenum volume or improve distribution. If it doesn't help it doesn't need it.