Reason for this post.............was the manifold opened too much?

My 55 Thunderbird has a stock 292 with a Holley electric fuel pump (measured 5.5 pounds of pressure), manifold vacuum is 20

I took my new to me B manifold to get the inside blasted since it was filled with rust.  I asked the machine shop to open the ports because my Edlebrock carb secondaries could not fully open.  I showed them a picture that Ted posted on a previous post.   They decided to open the the intake (see picture below) and cut the divider (that runs down the center of the manifold).  They probably removed half of the height of the divider because it was "better"
I can't get the car to "move" when I go to WOT from a dead stop.  The car actually stalls out if I don't start pumping the pedal.  It runs pretty good in all other scenarios (around town, highway), it even works fine from a dead stop "if" I slowly apply the throttle.......

If you have a stock 292, you should have left the B intake alone, other than possibly blocking off the heat crossover. 

I bought a Mummert aluminum intake. Although I haven't installed it yet, I would have preferred that the plenum divider was not notched; but it's a small notch. 


Moved the accelerator pump in all positions
Installed a richer Accel pump nozzle
Floats are set to 7/16" with a 15/16" drop
I've tried 3 additional jet and rod combinations per the tuning guide (one lean and two setting on the rich side) 
Tried different Edelbrock step up springs (per Edelbrock and vac readings I am settling on the silver springs
Initial timing is set to 15 degrees (Ive tried 10 to 20)  Distributor is a CRT
Tried adjusting the vacuum advance with the Allen/set screw and I also tried a limited plate for less vacuum advance
Tried ported and manifold vacuum for vac advance
I disconnected the trans kick down rod for a brief test
There is probably a few other things I can't remember at the moment.................so please ask away



Do you think the manifold "opening" could be causing the problem?   I really do NOT want to do this but today 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

Two things come to mind looking at your intake.  They should have milled the carb pad down to get rid of the open space  around the plenum so that it seals off the underside of the carburetor.  Second they should not have milled the divider down.  Proven to lose torque or have a torque dip at part throttle.  The carb pad can be milled completely flat and a 1/4" or 1/2" four hole spacer used to seal that area.  Eric Weingartner just proved that those slots hurt performance on dyno testing, and Ted and I did dyno testing and came to the conclusion that it almost always is a loss somewhere in the rpm band.  JMO, but I do not slot an intake for anyone unless it is strictly a race engine.  Joe-JDC  
This intake manifold on my 304 cubic inch EMC engine made 438 hp in testing before the Challenge.  We used a Mummert for the actual competition since it made about 14 more horsepower.  This manifold is fully ported and flows ~289cfm average.  The Mummert flow more.  

"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.

"Reason for this post.............was the manifold opened too much?"

I would say it was opened too much. Normally those slots are maybe .25 deep and 1 inch long? People say they help with "tuning" but the tuning they refer to is tuning for max power at high rpm, not off idle performance on a basically stock engine.
You're engine essentially has a single plane on it now.
Having said all that, maybe try adding less pump? Or turning in the idle mix screws? Sounds like its rich and bogging off the line. If it was lean I would think it would back fire out the carb. It's also hard to say if the manifold or the new carb is the issue since they were changed together and not one before the other.

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.

'I’m a bit puzzled why anyone would spend money modifying (especially experimentally) an iron manifold, when better performing/look-alike aluminum models are readily available, and with accurately predictable performance specs (?)."

A person may want improved performance without the added appearance of aftermarket speed parts.
Like a dedicated restoration whereas the outer appearance (CASTING and DATE CODES) has to appear as OEM   

I think you completely misunderstood what I said in my post about the void under that spacer between the intake manifold and the spacer.  That void is a disruption in the actual fuel distribution and will cause puddling, turbulence, and wetting down of the gasket under that spacer.  The spacer should sit flat on the carb pad, not raised around the edge of the original pad.   Have the shop mill the carb pad down flat like my picture and the issue will resolve itself.  JMO, but BTDT.  Joe-JDC

Again, read my description of what happens with the void under the carb spacer out to the edge of the carb flange area.  Wetting, puddling, and rich mixtures.  BTDT and watched it on dyno testing.  Check out Jon Kaase's You Tube on sticking his finger in a manifold while the engine is on the dyno and the fuel wash in the ports under the carburetors.  On my tunnel ram with wrong spacers, it was soaking wet due to the reversion under the carb.  The fuel needs to be directed into the manifold plenum, and not sucked up under the spacer and wetting the gasket and puddling.  Mill the carb plenum flat and get rid of the void and use a spacer and the problem will mostly go away.  That divider cut down will never get rid of the torque dip.  Joe-JDC

I am retired officially, but I ported heads and intakes for the last 54 years, specializing in Fords.  I always sand blast any iron intake manifold that is going to be ported before I do anything with it.  I sandblast the interior as well as the exterior and sometimes re-sandblast the interior to get a certain surface finish in the ports.  As far as the new TSP intakes, I have ported a couple of them already, and flowed several on my SF-600 flow bench.  It is a very good copy of the ECZ-B iron intake as far as flow at 189cfm, but not any better because of the small carburetor holes and small runners.  I had difficulty getting over 210 cfm with porting, and had to remove some of the ribbing at the down turns to get the flow up to 230cfm average.  I just flowed one of the newer Mummert dual plane intakes, and it averages over 283cfm.   The one I received from John last year averaged 272cfm.  You will need a spacer to fit any of the new Holley or Edelbrock or Summit carburetors unless you go with the 390cfm Holley with small butterflies.  You may have to bevel or enlarge the four holes for the spacers and carb to work properly.  Joe-JDC

Yes, you need to open up the venturi holes to match the spacer.  The lips under that spacer will cause terrible turbulence and be detrimental to your whole idea of getting the engine to run smoothly and accelerate smoothly.   That will allow the use of any of the more modern carburetors available.  If you stay with the four hole, then slotting the manifold to make a dual oval is not necessary.  However, you need to blend the bottom of the holes into the plenum to help the air/fuel turn into the ports easier.  Not a difficult task if you have a carbide burr and electric or air die grinder.  It is the little things that make any manifold work better.  Joe-JDC

If you plan on using the four hole spacer, then have the shop open the holes to match the spacer.  Simply install the four bolts and scribe the spacer openings.  Opening up the plenum to dual ovals requires an open spacer to scribe the outside edges.   If you don't plan on using an open spacer,  then only machine the four holes to match the spacer.  You have several options with the four holes opened up. 1/4", 1/2", 1", 2" spacers are available with four holes.   Joe-JDC