"I might put the original manifold back on and use a carb adapter to put the Edelbrock on the 55 intake.... I want to see if the problem is the carb or the manifold."

The throttle bores on the stock 55 intake are 1.5in and there is a transitional carb spacer that will allow the larger EDEL butterfly's to operate freely.

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I don't mind changing the manifold to test, which seems to be the only way to figure out what the problem is.  I don't want to buy a new manifold or go through the trouble of removing and replacing the manifold 2 more times. I was hoping someone here might say........."it's the carb", because Summit already is sending me a replacement.  Since Summit is the only vendor willing to help I would rather not exploit them and  "use" their replacement to trouble shoot what I believe to be someone else's problem..  

 Thinking about your suggestion, I did try the leanest pump shot and leaned out the primary jet and rod combination ( 1stage lean power and cruise), no change.  The best the carb performed was 2 stages rich power and cruise. One thing I didn't mention, the idle mixture screws were not very responsive to change, they we almost an on/off switch.  To get the idle and vac gauge to drop the screws were turned in about 1/4 turn from seated

It is difficult to diagnose and suggest fuel mixture problems here. Can on;y suggest pointing to TECH INFO as how to go about it on your end.

Have you used a VACUUM GAUGE to see if any vacuum leaks? The carb pad should have been shaved (as suggested previously).

Being a BIRD, it will be difficult to find a suitable spacer (heat isolation)/gaskets due to hood clearance.

EDEL has a CARB TECH BOOK.

READ HERE - https://www.enginelabs.com/engine-tech/intake-manifolds-single-plane-or-dual-plane/

PhD VERSION HERE - https://freshscientific.org/single-vs-dual-plane-intake

I think you are going to find that by eliminating the plenum divider that it is now a single plane and street duty is going to suffer. An EDEL  CARB is pretty forgiving.

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I used the vacuum gauge to adjust the idle mixture and to check timing.  It was a steady reading and went down and back up when blipping the throttle.
This is the spacer I used forgot to mention above.  I know the manifold looks like an abortion.  But the pad where the carb rests was done a CNC machine.  I don't think this is the problem.  This one reason why I wanted the base for the carb machined, in order to buy every 1/16" I could find.  I could not get a definitive answer on what spacer would fit my car before hand

I have a TSP aluminum ECZ-9425-B knock off that i don't need and would sell at my cost plus shipping.   These go for more now and there's an eBay seller that buys these from TSP and then does a crude job of slotting the bores and marks them up.  The slotting is rough, almost looks a hack saw job instead of machined.   The one I bought is brand new, never used or modified.   i recently made a comment on a facebook forum to Joe C's response to the seller's post.  My comment was that maybe I should sell mine if he's asking that much.  You are welcome to it.  I bought it because it was cheap at the time (discount coupon & free shipping) not less than a year ago.  I have a Blue Thunder intake I plan to use on my build instead.  I believe Ted Eaton has tested these and they perform as well as a stock cast iron ECZ-9425-B manifold.  Picture attached shows the TSP on the left and the Blue Thunder on the right.

What EDEL CARB MODEL NO. are you running?

You asked the machine shop to increase the carb pad throttle bore sizes (not opening slots) for the EDEL and they then sexually assaulted it?

I think you went about everything correctly but found a shop that didn't listen to customer want. They should have consulted/advised with you before doing what they did.

TECH ARTICLE -  https://www.eatonbalancing.com/2025/09/08/more-power-for-the-ford-y-block-part-3-of-5/#more-1847

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Ross.  You don’t mention if this particular carburetor was run previously and if so, what the differences were in performance.  Opening up that manifold with the lowered slot has reduced the manifold vacuum at idle and low rpm which in turn will affect and lean the fuel mixture in the lower rpm band.  But typically, fuel mixture and carb jetting changes will compensate for that.  As Joe has mentioned, the torque curve gets a bit erratic in different spots in the rpm band when the plenum divider is slotted and/or lowered and there’s no amount of carburetor adjustment that will eliminate that.

Also not mentioned are the specs on the camshaft as a reduced lobe centerline on the cam will be more sensitive to intake manifold plenum changes.  For street drivers, I do prefer a divided manifold plenum as that will typically result in a 1½-2” Hg manifold pressure increase which in turn gives a better signal to the carburetor.

I would suggest trying another ‘good’ carburetor on the combination as gut feel says this is a carb problem more than an intake problem.  At this point in time, a carburetor change will be easier than an intake manifold change.

Lorena, Texas (South of Waco)

6 VOLTS/POS. GRD. NW INDIANA

The carb is an AVS2 1901.  It is brand new.  No idea what cam is in the car, I would have to say it's the original.  Before this setup I had no problem getting 20 on the vac gauge at idle.  Now it seems like I'm struggling to get to 20.  I believe your estimate on1 1/2 pounds less is accurate

I just got the replacement carb from Summit and I had a bung welded to my exhaust for an AFR gauge with now needs to be wired up.... 

I am considering replacing the intake at some point, unless this makes a miraculous recover in the next couple of days