Edlebrock 7505 Air Gap

[hwoods]

Anyone have any experience with the Edlebrock 7505 Dual Quad Airgap Intake.  Price is attractive to other dual quand FE intakes.  I would want to adapt to run Holley Carbs

[wowens]

See Edelbrock dual quad plenum post below

[TorinoBP88]

Speedway sells a mr gasket offset carb space for Holley.

Or you can use edelbrock carbs. Prob decent driving, but...  May require custom tuning of butterfly weights to set secondaries to actually open.

[stuart olson]

If you are willing to go way out in the weeds you can run dual IMPCO 250 propane mixers on holley baseplates directly on any edlebrock dual quad manifold. Propane is around 112 octane and the mixers like to run below 3 inches of vacume across the venturis. Lets you run a real wild engine with good street manners. Tanks and convienient filling are another matter however.

[hwoods]

I used to work for a propane company, so I am familiar with propane powered vehicles

[BigBlueIron]

I have an old Edelbrock dual quad sitting on the shelf for just such a project, but I was going to use twin Impco 425 mixers.

[Falcon67]

I have run dual Ed 600s (1405 or  1406 with defeated choke) on a tunnel ram and I think you'd do well to consider that vs trying to squeeze a couple of Holley's on there with offset adapters that just interfere with air flow.  Offered for what it's worth.  I run/tune a lot of Holleys and Eds both - the Eds are good carbs when set up and maintained well, same as a Holley.  They actually meter fuel in their primaries much better than a run of the mill Holley which translates into better response on the street - if that's your thing.

[Royce]

Grab Jays manifold comparo book and look up the test he did on this manifold.  he ran a pair of Edelbrock 600s . Fuel curve was real nice and 0 vacuum.  Who knows what the Holleys might have done but those carbs worked well

[hwoods]

I have intended to pick up a copy of his book, just have not yet

[Falcon67]

Also, note the use of 600s.  The 500s are made for dual carb applications - but for some reason don't seem to be favored.  I believe Barry has done some work with the 500s and found they don't seem to work as well as the 600s.  In my application on a bitty 302, I actually had to "+1 step rich" both carbs, both primary and secondary to get best MPH on the track.  On a dual plane, the 33 shooters should be good, maybe the 28s.  On the tunnel ram, I drilled 33s to 35 to fix a slight lag.

[e philpott]

I bet some Mopar Hemi AFB's from a 66 to 71 street hemi would be a good match , surely someone has/restores them for the Hemi guys , I ran a matched set of 63 409 AFB Chevy carbs on my old 65 289 Mustang fastback with Cobra AFB 2x4 manifold that ran great on street back in the late 79 through the 80's

[Flucas Lucas]

due to blending variations throughout the year the amount of butane and other products can change to meet a vapor spec. HD-5 is what is considered consumer grade, which is what we all get at home or in bottles.

[Royce]

The only difference between 500s and 600s is the 500s have smaller boosters (I think).. At any rate since they only provide as much air as the engine demands, the bigger carbs work great.

[Joe-JDC]

I plan on using the Edelbrock 800 cfm Thunder series carbs on my 7505 Air Gap intake.  They should be just about perfect on a well ported intake and stroker FE.  Priced very reasonable for a 800 cfm new carb.  Joe-JDC

[mike_burch]

If you are willing to go way out in the weeds you can run dual IMPCO 250 propane mixers on holley baseplates directly on any edlebrock dual quad manifold. Propane is around 112 octane and the mixers like to run below 3 inches of vacume across the venturis. Lets you run a real wild engine with good street manners. Tanks and convienient filling are another matter however.

Just be aware that propane has a lot less energy than gasoline.  To get good power from it, the engine will have to be turbocharged/supercharged, etc.  Back in the 1980's, a friend's family was in the natural gas business, and ran all of his vehicles off propane.  There was a switch inside the cam you could slide between gasoline and propane.  When on propane, they had a LOT less power.  It has high octane, but unless you can blow a lot extra into the engine, it will be down on power compared to gasoline. 

Good Luck!