1956 Carburetor rebuilding…starts Tomorrow

[knuckle47]

so many posts I have read here over and over talk about how difficult and different these carbs are. My plan is to restore the 4 bbl carb on my 1956 312 cu.in, Starting tomorrow. All of the comments here do give me a bit of anxiety and apprehension for the outcome.

Can anyone who has successfully rebuilt this carb highlight any of the areas I should be alerted to? I am starting with the CASCO rebuild kit that was $143.00. Either scare me away or wish me luck?

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[HKelly]

Take lots of photos from all sides and top before you take it apart. Get a nice big area of a bench or table and line it with paper. Start disassembling it in stages. (Front bowl - take a photo then further disassembled then another photo etc). As I disassemble it I use a sharpie and circle the components and number them in the order removed. Now open your carb kit and assess what is in there. It is not uncommon to have extra parts as they generally do more than one style carb. Match up the correct gaskets, etc. start cleaning it very good. Pipe cleaners, carb spray, tooth brushes and small wire brushes, air gun. As your cleaning things you will need to pull the jets etc and squirt cleaner and blow air through ALL the passages. With the jet, sometimes they can be different sizes so note where they come from! Also be careful not to lose and ball bearings (check valves in carbs) refer to the build blowup in the carb kit and get to know the location of these things so you don’t lose them. If you do, or put something in out of order it can make tuning your carb next to impossible. Best advice is to dig up some you tube videos on it and you will get at least a little reference before you dive in. Take your time is the biggest one. Good luck!

 

[knuckle47]

I use the sharpie and brown paper isolation circles on many different things I’ve done and it is a great plan, I did even think of YouTube …It has proven helpful before so I’m searching for video once I finish writing this. Thanks for the good wishes. I will take a bunch of pictures along with the completed results as they occur. I am hoping 1 week so can install it next weekend but… plans change …LOL

 

[Ward 57]

I use the sharpie and brown paper isolation circles on many different things I’ve done and it is a great plan, I did even think of YouTube …It has proven helpful before so I’m searching for video once I finish writing this. Thanks for the good wishes. I will take a bunch of pictures along with the completed results as they occur. I am hoping 1 week so can install it next weekend but… plans change …LOL

Sounds like you have a nasty winter storm headed your way and you don't want to be fussing with cold metal unless you are one of those fortunate ones that has a heated garage.

 

[knuckle47]

Well it’s snowing right now… once I take the carb off the manifold, I head straight for the basement..it’s heated, I have an 8 foot table to use for layout and an 8 foot table for working. My concerns are for a mystical maze that is unreachable that requires a special tool that remains un-available or too expensive. The other tools I have left over from the days of dozens of Linkert and Zenith carburetor repairs. I am hoping I’m on the right right path and will post my end results. As I see it, if there is just no way to get it right, I’ll happily stop and ship it out to a rebuilder and will have learned a good lesson. It’s the one thing I have discovered over decades of sticking my nose where it possibly did not belong.

 

[Ward 57]

Well it’s snowing right now… once I take the carb off the manifold, I head straight for the basement..it’s heated, I have an 8 foot table to use for layout and an 8 foot table for working. My concerns are for a mystical maze that is unreachable that requires a special tool that remains un-available or too expensive. The other tools I have left over from the days of dozens of Linkert and Zenith carburetor repairs. I am hoping I’m on the right right path and will post my end results. As I see it, if there is just no way to get it right, I’ll happily stop and ship it out to a rebuilder and will have learned a good lesson. It’s the one thing I have discovered over decades of sticking my nose where it possibly did not belong.

Sounds like you have the experience to pull it off. With your prior experience with motorcycles and other carbs, you know 'finger' tight and wrist tight to not strip anything and the patience. Just hope the kit is made in USA along with the proper instructions also in plain English, I think you are good to go.
If it's not a 'T' pot carb you should be good and if it is there is tons of advice for those picky things.

 

[knuckle47]

You’ve got me @ward57. What does a “T” pot carb look like, is there a specific identification… it is a stock 312 cu.in. 4 bbl carb… funny but from its profile look, I’d almost say it looks like a teapot

 

[Shawnski]

One thing I found when I rebuilt mine was the fit of the power valve. The area is recessed and the new power valve didn't fit into the recessed area. I tried using a file on the new power valve which turned out to be a waste of time. Use a grinder with a fine stone or use a deremel tool.
Then use extreme caution when installing as the rubber side of the valve doesn't want to corroborate. It needs to be flat and seal all the way around and into the seat.
It took me about 4.5 hours to complete. I found that the linkage on the end of the butterfly shaft was loose, so I mixed up a little JB weld and did some doctoring. That needed another 12 hours to cure. When I reinstalled the following day, it took a while to get the bowl filled with fuel, but it started up nicely on fast idle as it should. After it was warmed up, I dis a little adjustment on the air/fuel mixer screws and it runs greats and idles really smooth.
Good Luck!

 

[knuckle47]

Good to hear @Shawnski Currently, my ‘56 needs to crank way too long before it even coughs enough to give positive feedback that it wants to start.
So much so that I’m also thinking the accelerator pump has given up. Might be a weak fuel delivery? A quick squirt of starting fluid makes a gigantic improvement. The base gasket weeps fuel and once started, idle is terrific, a quick bump of the accelerator and it hesitates. It could be several things but it there are just too many potential elements of age that remain unknown. If I can eliminate them all one at a time… I can move over to the next trouble spot.

Like any bike I have ever restored, I have no knowledge of the cars history…if I go over it all, I can look at it with a different eye when the next problem arises. I have only started watching this show around thanksgiving 2021 but there is a very heartwarming BUT expensive phrase on the TV show FantomWorks… it goes something like… we make cars better than when they first rolled off the line… I just love that. If I had that cash, I’d drop it off. Failing that, the only way it’s happening is me and you all answering my questions

 

[doug7740]

The Holly 4000 carburetor, standard equipment on 1955/56 Thunderbirds is a very good carburetor and probably one of the most misunderstood carburetors in existence. I have successfully rebuilt many of these carburetors and when properly rebuilt it is an excellent carburetor.

Some of the items you have to watch for are:

• Take your time with the power valve spring loaded diaphragm to make sure the rubber diaphragm is properly seated to the top.
• The discharge nozzles are always stuck in the bowl housing. Grind the tip of a screwdriver to fit into the keyhole-shaped recess in the top of the discharge nozzle. Try to move the nozzle back and forth, but take your time with this. Any movement at all is a sign that they will probably come out if you work them long enough. Sometimes adding some heat will help.
• Be careful when tightening the bowl lid to the main body. If the bowl lid is warped it will result in a vacuum leak behind the choke plates, because that is where the idle air bleeds are located.
• The spark valve that comes in the rebuild kit will be shorter than the original one. Don’t worry it’s just a newer design and will work the same.

That’s all I can think of at this moment, but I’m sure I will think of some other things later.

Mikes Carburetor Parts has a series of videos that deals with rebuilding the Holly 4000 carburetor.

Holley 2140 & 4000 Rebuild - Mikes Carburetor Parts

Holley 2140 & 4000, 4 barrel carburetor rebuild. Includes all of the videos we did while rebuilding a customers 4000.

www.carburetor-blog.com

Attached is the 1956 Holley 4000 Visual Aid Instruction Manual. Let me know if you need Holley 4000 carburetor manual, but since if is a large file I’ll have to clear it with the moderator first.

doug7740
1955 Thunderbird Blue

 

[knuckle47]

Doug, I am printing this out as I write this note… this is all some tasty information you have. I will commit your advice above to another printed page pinned to my work bench wall. Heading over to Mikes next…. A million thanks to you and all !

 

[knuckle47]

Rebuilt the ‘56 carburetor 2 weeks ago… installed it, started the car and it actually starts and runs great. But, here’s something I found that I was going to mention earlier but got a bit sidetracked. Originally thought this could be some 1960’s car guy mod, however, then it hit me…

This is somebody’s idea of a manual choke and it was quite possible this is why the engine never really started when cold or sitting. Me, I’m new to car stuff and read loads of stories about how these cars won’t start after sitting..so, I just went with it.

BAM ! A $2.00 lawn mower throttle control…. Mounted well under the dash…..Hahaha

I really should have known better after however many previous owners…motorcycles are so much simpler and smaller. You can see all the dumb stuff in minutes

 

[Ward 57]

Rebuilt the ‘56 carburetor 2 weeks ago… installed it, started the car and it actually starts and runs great. But, here’s something I found that I was going to mention earlier but got a bit sidetracked. Originally thought this could be some 1960’s car guy mod, however, then it hit me…

This is somebody’s idea of a manual choke and it was quite possible this is why the engine never really started when cold or sitting. Me, I’m new to car stuff and read loads of stories about how these cars won’t start after sitting..so, I just went with it.

BAM ! A $2.00 lawn mower throttle control…. Mounted well under the dash…..Hahaha

I really should have known better after however many previous owners…motorcycles are so much simpler and smaller. You can see all the dumb stuff in minutes

Thankfully I got my car when it was only 15yrs old. I think I'm the 3rd owner maybe fourth but I bought it from a neighbor's estate and got no previous history. As I dug into it I found some amateur fixits but didn't alter too much. At that time it was still considered just an 'Old car' 90% is still original and have been able to refurbish the original stuff. Still waiting for spring so I can finish the brake system, flexible hoses & booster has been rebuilt, M/C needs to be cleaned of rust and rebuilt and ready to install so it's road worthy but other than that it's just tinkering. Got a plan and I think have all the parts I need.

 

[knuckle47]

I know from my own experiences with some very great old bikes that were ruined by the creative thinking of previous owners. Cutting stuff off and re-shaping parts is always a tough one. I think you did it right… other than my mom’s , I have never really gotten close to old cars. My brother is a mustang nut. Big mustang nut.

Being it was nearly 70F today, it was so nice to go out and work on the car. Waiting for the roll pins to show up to fix the steering column hub separation that Doug provided me information on. Steering wheel came out good but the directional signal parts in the hub are attached with silicone caulk and some poorly fitting screws. I tested the directional switch with an ohm meter… seem like a bunch of effort to fix a few things

 

[Frankie the Fink]

Automatic chokes are one of the most misunderstood and mis-adjusted parts on vintage carbs of nearly ANY year and make...
They actually work when set up properly, and, quite well. It takes some patience and routine maintenance to keep them working correctly - parts wear out and on some designs carbon fouling can affect operation. Lots of owners add an "electric" choke kit (particularly on Holleys) that half wey work but usually "pull off" too quickly, and, manual (knob) conversion are bulletproof but ugly. Don;'t feel too badly early Cadillac dual quad cars had choes on BOTH carbs. Ugh!

 

[knuckle47]

@Frankie the Fink I was looking at the electric choke option and powering it via the coil. But, one of the things I was always so fussy about is to make a 80 year old motorcycle and bring it to its original specs for its production year and have it pass inspection. So if it never had one, it won’t get one. Eventually, the old timers at the inspection station would gather around and reminisce days in the 30’s and 40’s. It actually got to be fun. But the bike was presented in stock factory condition and passed. These carbs all just had a manual pull choke or a small lever. Some had no front brakes…. Factory.

The mechanical choke on the Holley proved to be more complex but it is moving freely, seems to do what it needs to but if it messes up in the near term, at least I am not intimidated anymore about going in and pulling the carb. I was even prepared enough by having 4 sets of base gaskets.