old timer intake trick?

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wazazzle

New Member

Mar 30, 2005

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In the dumpster behind McDonalds. WA

Aug 12, 2005

#1

• Aug 12, 2005

• #1

i heard an old timer trick to get the best of both worlds dual & single plane advantage was to take about 1" from the top of the plenum divider. don't really believe this but is this true? i was thinking of going with an old holly dominator single, but if i can p/u an dual modify as above i was going to do that if it works. thanks

 

302 coupe

Founding Member

Mar 2, 2000

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Macon, Ga.

Aug 12, 2005

#2

• Aug 12, 2005

• #2

I wouldn't do it. If it worked, everybody would be doing it.....

 

mfp4073

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Mar 14, 2001

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Hells Ditch, FL

Aug 12, 2005

#3

• Aug 12, 2005

• #3

if it worked as well as claimed, why would they not make them that way. You better believe that the intake companies have tested it.

 

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65myway

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Jul 13, 2004

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Melbourne, FL

Aug 12, 2005

#4

• Aug 12, 2005

• #4

Actually, if you look at a picture of the Edelbrock Air-Gap intake, it looks like this. Of course, it looks as if only about 1/2" is removed from the divider, but it is being done on aftermarket intakes.

 

4MuscleMachines

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Jul 20, 2005

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South Texas

Aug 12, 2005

#5

• Aug 12, 2005

• #5

Thats correct, Air-Gap intakes have about 1/2 inch removed from the top of the plenum divider.

 

tos

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Apr 27, 2001

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Cincinnati Ohio

Aug 12, 2005

#6

• Aug 12, 2005

• #6

This mod was done by engineers using alot of calculations and test equipment and maybe even an abicus (D.Hearne will get me for my spelling) so i wouldnt risk it on a known good intake Unless you had exact measurements and the proper tooling. Intakes arent real expensive so I would suggest buying one already done.

 

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bnickel

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Aug 21, 2002

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lubbock, texas

Aug 12, 2005

#7

• Aug 12, 2005

• #7

it's really not that scientific, the main reason that some intakes are like that is to help equalize flow between the two plenums, for the most part it really only works at higher rpms.

i beleive this mod was discovered accidentally when holley started making the 3 barrell carb and the intakes had to be modified to work the huge secondary butterfly.

if you do the mod it does not have be that scientific just cut out a notch about 1/2" to 3/4" deep. i would recommend that you actually cut the piece out as opposed to grinding it out, that way you could have the piece welded back in if you aren't happy with the results.

 

krash kendall

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Nov 19, 2004

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Aldergrove, B.C. Canada

Aug 12, 2005

#8

• Aug 12, 2005

• #8

Why not just put in a non-divided carb spacer? BTW- My 1" edelbrock spacer is divided to match the manifold.

 

tos

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Apr 27, 2001

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Cincinnati Ohio

Aug 12, 2005

#9

• Aug 12, 2005

• #9

How about a carb spacer, If you have the room under your hood that is. There only a few bucks at your local parts house and they have different variaties that I think will accomplish the same thing your going for. You can buy one opened in the center or hack one up how ever you like without loosing much money or time if it doesnt work.

 

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wazazzle

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Mar 30, 2005

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In the dumpster behind McDonalds. WA

Aug 12, 2005

#10

• Aug 12, 2005

• #10

think i'm gonna go with the open spacer and dual plane intake. thanks guys

 

brianj5600

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Sep 19, 2003

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Middle TN

Aug 12, 2005

#11

• Aug 12, 2005

• #11

Parts are modified all the time even though they are well engineered. There are companies like TEA that stay VERY busy improving well engineered parts. I doubt you will be able to feel a difference one way or the other. I think it will fepend on if your cam is too big for the intake.

 

Vinyl66

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Mar 21, 2004

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Aug 12, 2005

#12

• Aug 12, 2005

• #12

I ground the divider down some on my standard RPM intake to mimmick the RPM air gap intake. Did it work? I don't know. You would have to do back to back testing to know for sure. I figured it would help because the RPM air gap is a newer design and I don't think Edelbrock would do something to purposefully hurt horsepower.
An open carb spacer will do the same thing. Carb spacers seem to be a crap shoot. What works for one combination may not work for another. From what I have seen, a 1" heat insulating spacer (plastic, wood) usually seems to help. Open or 4 hole seems to be the crap shoot. I think I have seen more open spacers on dual planes because of the reasoning above and more 4 holes on single planes to give the carb booster a stronger signal.

 

2nd Mustang

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Feb 24, 2002

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Southern California

Aug 12, 2005

#13

• Aug 12, 2005

• #13

A little off the topic, but I took an old Holley 600 and cut off the airhorn over the primaries and removed the check ball in the vacuum secondary housing. Wow, the low end power really picked up! Just too much for street driving so put on a regular 600 again.

 

rbohm

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Apr 12, 2002

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tucson,az

Aug 13, 2005

#14

• Aug 13, 2005

• #14

cutting the plenum divider can help make power, as bnickle stated mostly in the upper rpm ranges, but it can also lose power as well. it depends on your combination, and what rpm range you are running in. the reason some builders modify the plenum divider is because a normal dual plane isnt enough, and a single plane is too much intake. but you need to dyno test the car to see if it helps or hurts at all. also any gains you see are normally going to be some what small overall, 5-10hp at best, so dont expect too much.

 

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bnickel

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Aug 21, 2002

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lubbock, texas

Aug 13, 2005

#15

• Aug 13, 2005

• #15

it's also especialy helpful if you have one bank running leaner than the other, as it will help even the mixture out. if you both banks are already running fairly equal you probably won't see much of a gain in HP but it will likely make some. but rbohm is right it could hurt performance as well.