Wonder why single plane intakes run, start and idle better than dual plane intakes on a big block?

1980RS

Veteran Member
Jun 17, 2006
6,635
MN
Good points 1980RS, and sometimes the term "porting" is used but "gasket matching" is actually done, and in some/many cases it's actually ruined, or hurt the engine potential performance more than it helped in many cases. I also have found in several cases that true Dual Planes can be "under carbed" and open plenums somewhat over carbed considering the engines requirements and effective rpm.

Some intakes are just so bad with casting shift and horrible port alignment it's not even worth putting the time in them, they are "New" and fuked right OOTB.

Here's 2 dyno sheets, same engine/dyno/fuel/timing/temps/carb, 4 hrs apart on the same day. Each intake was prepped by me and tuned as well, spacer(s) combo for each intake was optimized.

Not hard to see the trends by the rpm's in where the DP and OP like to operate in, it depends what the engine is going in and used for. The dual plane was getting funky in the upper rpms, even though the 333 cubes, without the spacers on the dual plane, the numbers were more spread apart.

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Boy I will tell you, them 2925 S/V intakes always impress me on whatever I have used them on. My 1st 406 ran great with one, my 358 ran well with one and my Vortec 406 screamed with a tiny cam to 10 sec territory with a Super Victor. It was just too bad the Vic Jr. did so poorly this year. My car was a dog with it but my buddies car ran super good with the Jr. Guess it was not a good match for my combo.
 

G72Zed

Veteran Member
Sep 8, 2015
4,411
Canada
Yep, the newer SV castings the last few years were much better/cleaner then the older models. I've learnt a few things what to do/not to do to those SV.

And, it all comes down to getting that intake tract/engine in a broader "positive harmonic" rpm range, sometimes spacer can send you a curve ball as well. There's a reason why the SV came after the Vic Jr. and not the other way around.
 

AEGIS43

Veteran Member
Lifetime Gold Member
May 16, 2008
303
Gilbert, AZ
Good points 1980RS, and sometimes the term "porting" is used but "gasket matching" is actually done, and in some/many cases it's actually ruined, or hurt the engine potential performance more than it helped in many cases. I also have found in several cases that true Dual Planes can be "under carbed" and open plenums somewhat over carbed considering the engines requirements and effective rpm.

Some intakes are just so bad with casting shift and horrible port alignment it's not even worth putting the time in them, they are "New" and fuked right OOTB.

Here's 2 dyno sheets, same engine/dyno/fuel/timing/temps/carb, 4 hrs apart on the same day. Each intake was prepped by me and tuned as well, spacer(s) combo for each intake was optimized.

Not hard to see the trends by the rpm's in where the DP and OP like to operate in, it depends what the engine is going in and used for. The dual plane was getting funky in the upper rpms, even though the 333 cubes, without the spacers on the dual plane, the numbers were more spread apart.

View attachment 151602 View attachment 151603
518 hp (dual plane), 541 hp (single plane) at 7000+ rpm out of a 333ci sbc?? That's an incredible little engine. I can't believe that is anything you would call streetable, is it? What's it like below 4000 rpm? Monster rear gear? I like to drive 75 mph down the freeway.
 

Rustbucket350

Veteran Member
Sep 4, 2013
1,366
Oviedo, Florida
I didn't think this would be such a touchy topic. What are we really seeing with a spacer on the dyno? A few hp. It's pretty insignificant. Plus, any intake that is properly matched to the cam and head will outperform something that is just bolted onto a stock engine (if anyone even does that these days).

On that note I like to match the engine powerband to the rear gear and converter. It's not so much about what intake will make more power. It's about what you want.

Carb spacers for power? Eh might get a few. Who cares. You'll never notice.

On that note, yes, a single plane will outperform a dual plane. Every time if the engine is built right. They definitely do have different characteristics. I have not personally been disappointed by any single plane intake. I do run dual planes if the combination requires it.

Just my thoughts. I like to give them all of the rippums. (Rpms).
 
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1980RS

Veteran Member
Jun 17, 2006
6,635
MN
I didn't think this would be such a touchy topic. What are we really seeing with a spacer on the dyno? A few hp. It's pretty insignificant. Plus, any intake that is properly matched to the cam and head will outperform something that is just bolted onto a stock engine (if anyone even does that these days).

On that note I like to match the engine powerband to the rear gear and converter. It's not so much about what intake will make more power. It's about what you want.

Carb spacers for power? Eh might get a few. Who cares. You'll never notice.

On that note, yes, a single plane will outperform a dual plane. Every time if the engine is built right. They definitely do have different characteristics. I have not personally been disappointed by any single plane intake. I do run dual planes if the combination requires it.

Just my thoughts. I like to give them all of the rippums. (Rpms).
When I can just put on a spacer and my car picks up over a tenth and 1 mph, that's the cheapest HP I can get. I have yet to have any intake that did not work a little better without a spacer over the last 20 years. Track results never lie. Besides they look cool too.
 

AEGIS43

Veteran Member
Lifetime Gold Member
May 16, 2008
303
Gilbert, AZ
I was wondering if we jacked @450bench 's thread, but I don't think we did. I think there's been some really good discussions and opinions.

AND WE NEED MORE BBC VEGA PICS
 

G72Zed

Veteran Member
Sep 8, 2015
4,411
Canada
I didn't think this would be such a touchy topic. What are we really seeing with a spacer on the dyno? A few hp. It's pretty insignificant.

I would actually say it's an interesting topic, not touchy.

It's insignificant if that's the only data line one is looking at and judging by. I equate this to looking at different cylinder heads and only looking at CFM numbers as a comparable, not seeing the bigger picture.
 

G72Zed

Veteran Member
Sep 8, 2015
4,411
Canada
518 hp (dual plane), 541 hp (single plane) at 7000+ rpm out of a 333ci sbc?? That's an incredible little engine. I can't believe that is anything you would call streetable, is it? What's it like below 4000 rpm? Monster rear gear? I like to drive 75 mph down the freeway.

Yes Sir and thank you. It's a typical 4.040 bore with a 3.250 stroke bottom end that's been "rubbed on"

I was doing R&D to see how far I could push that dual plane's upper rpm power limit with a couple of dozen spacers, many custom made. I got my answer.

Hence the reason why I chimed into this thread that 450bench started, I'm in the same camp as he is as well.

Actually I'm pushing 30k street miles since 2014, it's actually very streetable. Below 4k, just go easy on the gas and it won't bite you LOL. I use a 3.73 rear gear, but my old Richmond RR 5spd had a 2.89 1st gear with a .77 5th. My TR6060 6spd has a 2.97 1st gear with a .80 5th, and .63 6th.

I like to drive 75-80 mph on the highway as well, I can cruise at 2,200 rpm with ease in 5th or 6th. I get almost 21 mpg on the highway, even the new combo that's now 362 cube and making almost 40 ft lbs more tq is still 20+ mpg's.


327 Sportman II build Dyno test.JPG MPH check.jpg
 

AEGIS43

Veteran Member
Lifetime Gold Member
May 16, 2008
303
Gilbert, AZ
Yes Sir and thank you. It's a typical 4.040 bore with a 3.250 stroke bottom end that's been "rubbed on"

I was doing R&D to see how far I could push that dual plane's upper rpm power limit with a couple of dozen spacers, many custom made. I got my answer.

Hence the reason why I chimed into this thread that 450bench started, I'm in the same camp as he is as well.

Actually I'm pushing 30k street miles since 2014, it's actually very streetable. Below 4k, just go easy on the gas and it won't bite you LOL. I use a 3.73 rear gear, but my old Richmond RR 5spd had a 2.89 1st gear with a .77 5th. My TR6060 6spd has a 2.97 1st gear with a .80 5th, and .63 6th.

I like to drive 75-80 mph on the highway as well, I can cruise at 2,200 rpm with ease in 5th or 6th. I get almost 21 mpg on the highway, even the new combo that's now 362 cube and making almost 40 ft lbs more tq is still 20+ mpg's.


View attachment 151721 View attachment 151722
That's incredible. So awesome.
 

450bench

Veteran Member
Feb 25, 2002
3,738
memphis, tn-shelby
That is awesome.

I can tell you with my little Vega, the Edelbrock Streetmaster is NOTICEABLY faster, more responsive, has zero flat spots and easier to start than when I had the air gap on it. The difference is very surprising.
My engine is a 9 to 1 468, open chamber oval port aluminum heads, smallest thumper hydraulic cam, 870 Holley vacuum secondary, 2 1/8 inch headers, m20 4 speed and a 2.73 gear.
I only made the intake swap so I could put a stock hood on the car. I’ve always loved the Streetmaster on mild big blocks but as I said the difference in performance is crazy.
(Gotta paint the hood soon)
 

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