I completed changing out all (8) spark plugs last night with new Autolite 216s gapped at 0.032". The old plugs had all sorts of issues to include (3) with non-compressed plug rings (finger tight) and (2) with less than 0.24" gaps. I thought I had this whipped, so I immediately took her out for a test drive only to face disappointment ---the performance didn't change much. The idle vacuum @450 rpm is still a mere 15" and the engine still stumbles/misses beginning at 3,000rpm. Keep in mind this stumble/miss occurs as I gradually approach 3,000 rpm (I'm not instantaneously pedaling it to to the metal). 

So now I find myself facing that old, "is it the ignition vs. carburation" dilemma. A couple of more observations I'd like to share with you:

1. When in Neutral and idling with no load, the engine's rpms will instantly rev from 450 rpm  to 4500  - 4700 rpm each time I wrap the accelerator pedal. I can do this 4- 5 times in quick succession and the engine responds flawlessly. Wouldn't this TEND TO INDICATE the ignition system is PROBABLY not the primary issue? As a minimum I believe this allows me to rule out bad points or a bad condenser.  However the dizzy curve still remains in question.
    
2. Regarding the 2140 Teapot ---I must fess this is my first rodeo with such a carb. It bothers me that the choke tube, which projects up through the base of the carb and into the carb air- cleaner (as a source of clean air), is CONSTANTLY DRAWING VACUUM (to heat the bi-metallic spring in the choke assembly). Is this tube supposed to constantly suck air or should it only draw air during the choke heat-up period? The intake with the Integrated choke housing is also a first for me (see pics below)

Thanks for all of your support on helping me "debug" this engine. The previous owner did his part in getting the engine reassembled and stabbed back into the bay but he unfortunately "ran out of time (88) and funds" to finish sorting her out for reliable performance street use. This has become my job and contribution to our beloved hobby (bedeviled at times too).           



   
    

"Is this tube supposed to constantly suck air or should it only draw air during the choke heat-up period? The intake with the Integrated choke housing is also a first for me (see pics below)."

Yes, continuous draw as it provides fresh inlet air for the choke (stove) operation (vacuum) and as a coolant so as not allow  the thermostat coil to over heat). The carb is calibrated to allow for that vacuum draw.

Is this heat related, say does it breakdown at cold operation or when heated (coolant)? The COND may be breaking down with heat. Remember, when you floor it at stand still, there is very little load on the engine.

You're planning on adding an EDEL CARB later? What about the divorced choke style on your present intake. Are you going to use a later intake? You have a DUAL ADV DIST in good health?

You do have TED'S TECH ARTICLE on how to modify that carb to use with a DUAL ADVANCE DIST?

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Thanks for the explanation on how this style choke mechanism works and confirming the tube continuously draws air.

I’ll try accelerating above 3000 rpm when the engine coolant is “cool” tomorrow morning and report back.

Indeed my plan is to replace the Teapot and existing intake with a 500 cfm Edelbrock AVS2, a ‘57 intake (sans choke tube), and ‘57 dual dizzy. The ‘57 intake has been media blasted, inspected for cracks, painted etc. and the ‘57 dizzy completely rebuilt. I also purchased the correct hex oil pump drive to mate onto the dizzy. I refer to all of these parts as the “‘57 package.”

I’ve read TED’s article and will probably take the intermediate step of modifying the Teapot to enable it to run with the ‘57 intake, dizzy, hex drive BEFORE installing the Edelbrock. If this combo runs good I might even forgo the Teapot/Edelbrock swap to retain the factory look (especially the Factory Air Cleaner). Now that would be neat!

But before embarking on this eventual ‘57 Package swap I think it prudent to first sort out the vacuum and stumble issue and effectively establish the factory engine’s “baseline” performance. Understanding this baseline being necessary to honestly judge the before and after benefits of the swap…

I’m going to stick to this plan for a bit more and continue crossing possible causes off the list. I might find out that this path was a mistake and waste of time e.g. when I finally give up and pull the ‘54 intake off, to swap in the ‘57 intake, I find THE CAUSE —a torn intake gasket!” Nobody ever said the scientific method was painless or cheap. Which reminds me—off I go to pray again that it’s not the rings.


More to come.

"I’ve read TED’s article and will probably take the intermediate step of modifying the Teapot to enable it to run with the ‘57 intake, dizzy, hex drive BEFORE installing the Edelbrock. If this combo runs good I might even forgo the Teapot/Edelbrock swap to retain the factory look (especially the Factory Air Cleaner). Now that would be neat"

That to me (personally) would be sweet as it will retain factory install appearance.

You stated previously when first driven, it appeared the TV LINKAGE was not adjusted correctly and then you made some adjustment(s) and she seemed to then shift correctly. The curb idle is dictated by correct throttle linkage adj. as it will allow proper throttle linkage adj. and that is tied directly to TV adj. May be why the curb idle adj. screw won't control curb idle screw to adjust properly. To properly adjust throttle linkage curb idle and TV linkage is a fairly complex adj. that will be found in your LINC WSM. It has to be dead-on as one works off the other.

As for the vacuum reading. It is low (too low) for a stock camshaft (at what altitude do you live?).

1) Need to perform cylinder(s) leak-down test to determine if the rings are good or not. Only GOD knows the quality of the rebuild and what was or not done (and how long it sat before initial fire/break-in).

2) The vacuum gauge also shows possible late valve timing and/or late IGN timing. IMO, the balancer indexing needs to be confirmed with a piston-stop method. If the balancer is indexed correctly, you then proceed further with diagnostics from there.

3) It needs a fuel pressure and delivery volume test performed. Any indication of the carb being gone through? The volume test ( caught in a glass container) will also identify any trash in the fuel system. Again, only GOD knows how long she sat with sour fuel in the tank,

You are aware LINC/MERC used a square bore 4V carb mounting pattern until the LYB was finally replaced? The only true wide mounting pattern carb intake manifold was found on the LYB 332CI HT engine so the EDEL carb will require an adapter.

You say you have a LYB DUAL POINT DIST? Is it FORD or aftermarket? If FORD, can you post the DIST ID NOS.?

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"I’ll try accelerating above 3000 rpm when the engine coolant is “cool” tomorrow morning and report back."

What you are trying to do here is determine if the tip-in hesitation happens when the engine is cold (choke closed) or warmed (choke open). If no hesitation with the choke closed, it may indicate a lean condition without the choke. If the hesitation happens when the engine is warm, it may indicate a timing problem, bad condenser (when heated) or possible valve float.

Again, the DIST timing curve has to be verified (and this includes the CARB SPARK CONTROL VALVE).

Carry a note pad with you and when it does happen watch the vacuum gauge.

QUESTION - Is Nos. 7 and  8 plugs hard to get to due to the integral PS steering box design and size?

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"You stated previously when first driven, it appeared the TV LINKAGE was not adjusted correctly and then you made some adjustment(s) and she seemed to then shift correctly. The curb idle is dictated by correct throttle linkage adj. as it will allow proper throttle linkage adj. and that is tied directly to TV adj. May be why the curb idle adj. screw won't control curb idle screw to adjust properly. To properly adjust throttle linkage curb idle and TV linkage is a fairly complex adj. that will be found in your LINC WSM. It has to be dead-on as one works off the other."

Troubleshooting why the curb idle screw has to be completely backed-off the shaft in order to tame the engine down to 450rpm, I completely disconnected the throttle linkage from the Teapot to ensure the TV Linkage assembly wasn't inadvertently pulling on the throttle. No tension, same outcome. Next time I pull the Teapot, which was rebuilt, I'll check the secondary plates aren't open too much ---WSM calls for 0.004" gap using 3/8" shim. 

Regarding the Edelbrock carb adapter--Somewhere on this site I read Ted machines the 4V intakes to remove the 4 holes and mills down the carb mounting surface. I might contact him for this service once I've solved some of these other unknowns. 

Changing plug 7 was a pain but managed to finally get at it from below the car. Plug 8? There is no Plug 8! Please don't mention Plug 8 again. LOL

(Snaked 8 past the PS box but not before depositing 1.3oz of right hand skin)

"Troubleshooting why the curb idle screw has to be completely backed-off the shaft in order to tame the engine down to 450rpm, I completely disconnected the throttle linkage from the Teapot to ensure the TV Linkage assembly wasn't inadvertently pulling on the throttle. No tension, same outcome. Next time I pull the Teapot, which was rebuilt, I'll check the secondary plates aren't open too much ---WSM calls for 0.004" gap using 3/8" shim."

GOOD DIAGNOSIS!

You are ahead of me ...

FORGOT TO MENTION -

Make sure your choke fast idle cam is adjusted correctly and completely falls.

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"You are aware LINC/MERC used a square bore 4V carb mounting pattern until the LYB was finally replaced? The only true wide mounting pattern carb intake manifold was found on the LYB 332CI HT engine so the EDEL carb will require an adapter."

"Regarding the Edelbrock carb adapter--Somewhere on this site I read Ted machines the 4V intakes to remove the 4 holes and mills down the carb mounting surface. I might contact him for this service once I've solved some of these other unknowns."

I think maybe you are confusing the FYB intake and the LYB intake.

LYB had a very low carb mounting pad on all applications I a$$-u-me for ACL clearance. To mount the EDEL, you will need to use a spacer and an adapter to clear the runner(s). If you do decide to go this route (which is none of my business) make sure to check that the OEM ACL will allow the hood to be shut.

Watch These Two Videos - How to Update the Lincoln 368CI Carburetor 1956 & 1957 Lincoln

https://www.youtube.com/watch?v=N-J4L5K2pF4
https://www.youtube.com/watch?v=pqPqne1Li_c



If I understood you incorrectly, please go easy on me. I am old and very fragile ...

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I "made" such an adapter for a FYB 9425-A intake a long time ago.  I picked up a 1" aluminum carb spacer and gasket matched the mounting holes, drilled and countersunk them so the Allen bolt heads would allow a carburetor to sit flat, and then bolted an Edelbrock 500 on.  That woke my 272 up big time from the old 2BBL that was on it.  

Appreciate the info and videos! on how to properly machining/set-up an '57 intake for a newer pattern 4bbl Edelbrock! Wish I had one of those nifty modern 4BBL 332 Intakes instead. This intake must be a rare duck.

Once ready for the intake swap, I plan on using this adapter:
https://www.speedwaymotors.com/Holley-Edelbrock-to-Carter-WCFB-4-Barrel-Carburetor-Adapter-Plate,5551.html

Speaking of ducks  ---rain is finally falling again in Northern CA. Wet conditions forecasted or another 2-3 days. I'll use this downtime to poke around the engine some more in search of the cause of the low vacuum/zero curb idle setting. I'll report out...