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By DANIEL TINDER - Last Month
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Rough running/exhaust popping/hard starting after warmup, plus bubbling sound from carb area (eventually dies down, but returns upon throttle fully opened). Starts & runs normally when cold though. Carb mod has power valve continuously open, btw. Ideas?
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By Robs36Ford - 7 days ago
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Sounds like lean, Check fuel pump for weak pressure or flow .... ?
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By Ted - 7 days ago
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The vacuum for the power valve on the model 4000 Holley is independent of the spark advance valve. The power valve is the brass valve between the main jets in the fuel bowl while the spark advance valve is located on the side of the carburetor. What carb modification are you referring to?
Are the idle mixture screws responsive? Screwing them all the way shuts off the engine? One to one and half turns out on each is normal for a stock camshaft. Any vacuum leaks will upset the idle and cause the popping noise you mention.
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By DANIEL TINDER - Last Month
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Robs36Ford (8/25/2025)
Sounds like lean, Check fuel pump for weak pressure or flow .... ?
No change when I switch on the electric auxiliary pump.
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By DANIEL TINDER - Last Month
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Ted (8/25/2025)
The vacuum for the power valve on the model 4000 Holley is independent of the spark advance valve. The power valve is the brass valve between the main jets in the fuel bowl while the spark advance valve is located on the side of the carburetor. What carb modification are you referring to? Are the idle mixture screws responsive? Screwing them all the way shuts off the engine? One to one and half turns out on each is normal for a stock camshaft. Any vacuum leaks will upset the idle and cause the popping noise you mention.
Carb mod: Oversized AC stud attached to the float cover (threads in body stripped), but not sealed, thus no vacuum to close the power valve.
Normal running when cold, and bubbling noise from carb area (returning when throttle floored) after warm shutdown is what’s puzzling.
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By Ted - 6 days ago
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Looks like we are back to the engine running lean when it’s hot. You might try disconnecting the distributor vacuum line and see if that helps. Beyond that, then low carburetor float level, vacuum leak(s), idle mixture screws improperly set, valve lash, ignition timing are just a few other things to look at.
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By paul2748 - 6 days ago
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Sounds like you need another carb. Shouldn't be that hard to locate another 55 teapot
DANIEL TINDER (8/26/2025)
Carb mod: Oversized AC stud attached to the float cover (threads in body stripped), but not sealed, thus no vacuum to close the power valve. Normal running when cold, and bubbling noise from carb area (returning when throttle floored) after warm shutdown is what’s puzzling. [/quote]
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By DANIEL TINDER - Last Month
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paul2748 (8/26/2025)
Sounds like you need another carb. Shouldn't be that hard to locate another 55 teapot.
I’ll likely just finally install the modern Holley I have put aside, and leave the teapot issue to whatever restorer ends up with my car 😁 (after I check the possibilities that shouldn’t only occur when engine warms, or causes a bubbling sound).
P.S. I wonder, if anyone has filled the market void left when PONY went out of business? Seems like most current rebuilders lack that same level of tech sophistication.
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By DANIEL TINDER - Last Month
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My quoted post text disappeared (go figure).
Was just curious if anybody has filled the market void left when PONY went out of business? (Same level of tech sophistication).
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By paul2748 - 5 days ago
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Are you looking for a rebuilder for your teapot ? These guys specialize in teapots:
Sal Cicala 586-612-1650
David Arey 610-837-6146
DANIEL TINDER (8/27/2025)
My quoted post text disappeared (go figure). Was just curious if anybody has filled the market void left when PONY went out of business? (Same level of tech sophistication).
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By DANIEL TINDER - Last Month
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paul2748 (8/27/2025)
Are you looking for a rebuilder for your teapot ? These guys specialize in teapots:
Sal Cicala 586-612-1650
David Arey 610-837-6146
One has no cores or parts, the other seems less than technically responsive.
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By KULTULZ - Last Month
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CHECK THIS OUT - https://www.hotrodreverend.com/post/1955-ford-holley-4000-rebuild
Also - https://www.carburetor-parts.com/holley-4000-parts
And - https://www.carburetor-blog.com/article-categories/holley-4000/
https://www.carburetor-blog.com/knowledge-base/4000-rebuild/
It all depends on far you want to go with it regarding rebuild/restoration.
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By Ted - 4 days ago
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Daniel. Is your particular carb a List #1077 or #1078? The list numbers will be found at the rear lower flange of the carb. These two numbers were particular to the 1955 Thunderbird. Are you looking to simply repair your carb or replace it? And if replacing it, are you looking for the correct numbered carb for your application or would a non-correct number Holley 4V model 4000 carb be suitable?
Here’s the link to a past thread showing the List numbers of the various model 4000 carbs used by Ford.
http://forums.y-blocksforever.com/FindPost167355.aspx
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By DANIEL TINDER - Last Month
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Interesting, thanks.
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By DANIEL TINDER - Last Month
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Ted (8/28/2025)
Daniel. Is your particular carb a List #1077 or #1078? The list numbers will be found at the rear lower flange of the carb. These two numbers were particular to the 1955 Thunderbird. Are you looking to simply repair your carb or replace it? And if replacing it, are you looking for the correct numbered carb for your application or would a non-correct number Holley 4V model 4000 carb be suitable? Here’s the link to a past thread showing the List numbers of the various model 4000 carbs used by Ford. http://forums.y-blocksforever.com/FindPost167355.aspx
I never thought to check the list # of the refurbished 4000 PONY sold me. Guess I should.
Don't know what they did to make it run so much stronger than the locally rebuilt orig (which I now wish I hadn’t sold), but if I could only diagnose my current issue, I would just have it rebuilt (assuming the AC stud threads could be repaired, and I could find a replacement float cover), unless it’s secret could be discerned & duplicated.
Once I eliminate other factors (lash, timing, etc.), I may just forget it and install the new Holley & BT manifold though.
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By KULTULZ - 3 days ago
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"I never thought to check the list # of the refurbished 4000 PONY sold me. Guess I should.
Don't know what they did to make it run so much stronger than the locally rebuilt orig (which I now wish I hadn’t sold), but if I could only diagnose my current issue, I would just have it rebuilt (assuming the AC stud threads could be repaired, and I could find a replacement float cover)"
So the carb you have mounted now is not the car assembly carb but a modified H4000 from PONY CARB (and yes, they were good)? And you sold the original carb? Can you post the LIST NO. of the present carb?
I think Ted has a correct LIST NO(s). core he is offering you. Most likely your present carb needs to be gone through, especially if has running ethanol laced gasoline. Plus it was modified by PONY CARB.
Is your BIRD a driver, survivor or restoration ? Do you plan on restoring it (numbers correct)?
There are services out there that can fully restore the carb further than what I showed above. They (above) are more in the line of service repair.
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By KULTULZ - 3 days ago
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Maybe these will be helpful -
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By DANIEL TINDER - Last Month
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Looks like a #1078. Car is a driver. Even with mostly premium fuel, 70K miles with any alcohol content likely means it’s due for a rebuild. But, an academic issue if I change to the new Holley. A lot of trouble & expense only to benefit an eventual restorer. I wonder if it would be safe to run the motor with the float cover off? If gas is draining/leaking into the manifold faster than the pump can fill, that might explain the bubbling sound (and why it runs fine initially).
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By KULTULZ - Yesterday
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You post 'anther carburetor'. Do you mean you have a later style carb that you want to install (update) rather than repairing the present H4000?
Peruse through this site (lots of TECH) - https://www.carburetor-blog.com/knowledge-base/4000-rebuild/
If you don't come across an answer, maybe call and see if he as an opinion.
I have never been into one. In fact, the first time I actually saw one, it took me a little off as I started with FE with either a F4100 or H4150.
If your present H4000 was gone through and modified by PONY CARB, I would try and have that one repaired. Maybe buy a core for parts.
Let the board know what you decide.
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By Robs36Ford - Yesterday
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The cover has several of the air bleeds that control the fuel timing at different RPM. Running without, for other than idle and just off idle, would not work well at all. But as a test after the engine is hot, pull it off to see if it is flooding or boiling fuel.
Ensure your Fire Extinguisher is handy and charged !
Bubbling sounds are usually the gas boiling due to heat soak or lots of air getting in.
Do you have a phenolic carb spacer ? It's 1/2" and black colour under the carb to stop the heat from the intake. Without the spacer the carb WILL get too HOT !
Is your exhaust heat crossover leaking ? that could cause extra flow of hot exhaust into carb area making the fuel boil. I believe the 55 has an intake mounted choke. Was that changed to the later Carb mounted style ?
If the fuel filter has clogged and broken that could let dirt into the needle and seat of the carb making it flood the engine. but that would continue even when the engine cools down.
Just a few thoughts.... :-)
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By DANIEL TINDER - 6 hours ago
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KULTULZ (9/1/2025)
You post 'anther carburetor'. Do you mean you have a later style carb that you want to install (update) rather than repairing the present
New 465 HOLLEY. Manual says elect. choke needs 12V though. I have a small transformer that might work in case. Also have to likely rig the linkage.
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By DANIEL TINDER - 5 hours ago
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Robs36Ford (9/1/2025)
The cover has several of the air bleeds that control the fuel timing at different RPM. Running without, for other than idle and just off idle, would not work well at all. But as a test after the engine is hot, pull it off to see if it is flooding or boiling fuel. Ensure your Fire Extinguisher is handy and charged ! Bubbling sounds are usually the gas boiling due to heat soak or lots of air getting in. Do you have a phenolic carb spacer ? It's 1/2" and black colour under the carb to stop the heat from the intake. Without the spacer the carb WILL get too HOT ! Is your exhaust heat crossover leaking ? that could cause extra flow of hot exhaust into carb area making the fuel boil. I believe the 55 has an intake mounted choke. Was that changed to the later Carb mounted style ? If the fuel filter has clogged and broken that could let dirt into the needle and seat of the carb making it flood the engine. but that would continue even when the engine cools down. Just a few thoughts.... :-)
Car ran great, even with the power valve continuously open (just poor mileage). Believe I’ll warm the motor with only a couple float cover bolts barely snugged, and then pull the cover quickly to check the level. I’ll run only the aux. elect. pump first with the cover off, to check it before starting. If the crossover IS leaking, then the teapot issue is indeed null. Carb body doesn’t feel hot though. Mystery is why after the bubbling dies down, opening the throttle starts it again (?). |
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By Robs36Ford - 3 hours ago
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Another thing that can make bubbling noise is low coolant
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