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Noticed the carb was leaking quite bad the other day from the lower half. I have a picture. I think it’s time for a rebuild but I’ve never done one, I’ve always brought it to a carb shop. How difficult is it? Any pointers for me in case I decide to try it? Thanks guys.
Honestly - Piece of cake walk in the park. Purchase the correct carb. rebuild kit based on your carb. model number. Spend the extra several beans for a good kit - it will contain new springs, ethanol resistance accelerator pump, and excellent gaskets. Be patient & methodical. Have several containers on hand beforehand (tupperware, cottage cheese containers, yogurt, etc.) to hold parts you remove. Air compressor jet nozzle, a set of carb. cleaning tools but not required, tooth brush, can of carb. cleaner, etc. After a thorough cleaning, place carb. on a dead level surface & examine for any possible warpiing. Tons of videos available. What model number Rochester? Kits are available from many places. Everyone will have a favorite place to buy. Review several of the available kits before you make a decision. Don't make it difficult - it really is a very simple deal.
EDIT: You need to know the three fundamental pieces (stages) of a carburetor. I'll see what I can dig up. May not be your exact model number, but may be as well.
Last edited by Vintage Chief; May 11, 2024 at 03:44 PM.
Rather than me reinventing the wheel, here's a decent thread w/ good information - give it a read.
The three fundamental stages of the Rochester: (1) Air Horn Assembly, (2) Float Bowl Assembly, (3) Throttle Body Assembly (with a gasket between each). Pretty simple stuff, really. Have at it.
I have (made) a 2"x4" board stand I use which I can sit the carburetor onto. Others use some nuts/bolts to create a stand using the carb. holes which mount to intake manifold. Having it stationary helps, IMO. You can walk away, leave it sit, etc. just creates a tidy work surface/area to work from.
Carb bolt holes Carb bolt holes align to platform Some cleaning tools. Simple 2x4 platform. Basics of a Rochester carb.
Examine the brass? fuel inlet nut for leakage, it appears work has been done there.
I thought the leak was initially coming from it, but it wasn’t. That’s the original inlet brass fitting. I should look to replace it but it does have strange threads. 1/8 NPT inner threads where the fuel enters that fitting.
I have (made) a 2"x4" board stand I use which I can sit the carburetor onto. Others use some nuts/bolts to create a stand using the carb. holes which mount to intake manifold. Having it stationary helps, IMO. You can walk away, leave it sit, etc. just creates a tidy work surface/area to work from.
Carb bolt holes Carb bolt holes align to platform Some cleaning tools. Simple 2x4 platform. Basics of a Rochester carb.
Norm, this is my setup. I used four studs I had saved and just threaded them into two blocks of wood. Allows me to operate the carb and is good and sturdy.
Is the number I have in the pics the model number? Where should I look for that model so I can order the proper rebuild kit.
Also, are these small retaining clips ok to use? Which are best between the cotter-looking ones and the black “c” clips?
My little stand, with studs, holding the carb Opinion on these clips? Or these? Is this the model of the carb?
There is a lot of difference, the Quadrajet came out in '66. It is a spread bore with manually operated secondary throttle plates on the bottom third of the carburetor and an air valve/flap on top of the carburetor that gets pulled open by air flowing past it when the lower throttle plates open. When the air valve on the top opens it causes the secondary metering rods to raise out of the secondary jets, it is a quite tunable nice streetable carburetor. The vast majority were made by Rochester a small percentage were made by Carter, other than the manufacturer I've not seen a difference between them. I've never seen a Carter Quadrajet on anything other than Chevrolet's.
All Quadrajets are four barrels; but, not all four barrels are Quadrajet's
Last edited by Sugar Bear; May 11, 2024 at 07:23 PM.
There is a lot of difference, the Quadrajet came out in '66. It is a spread bore with manually operated secondary throttle plates on the bottom third of the carburetor and an air valve/flap on top of the carburetor that gets pulled open by air flowing past it when the lower throttle plates open. When the air valve on the top opens it causes the secondary metering rods to raise out of the secondary jets, it is a quite tunable nice streetable carburetor. The vast majority were made by Rochester a small percentage were made by Carter, other than the manufacturer I've not seen a difference between them. I've never seen a Carter Quadrajet on anything other than Chevrolet's.
All Quadrajets are four barrels; but, not all four barrels are Quadrajet's
I’m having a hard time figuring out my model number so that I get the correct rebuild kit. Any idea where that number is on the carb??? I see multiple numbers but they are only 5 digits long 🤷🏻♂️
I’m having a hard time figuring out my model number so that I get the correct rebuild kit. Any idea where that number is on the carb??? I see multiple numbers but they are only 5 digits long 🤷🏻♂️
Ignore all the banter about the Quadrajet.
The carb you have is a 4GC.
The carb model number is on a small three cornered tag attached to one of the air horn screws.
If it is missing, don't worry, most 4GC's take the same carb kit.
Just ask for a kit for a '61 Olds 4 barrel.
Here is a thread on re-building a 4GC carb.
Ignore all the banter about the Quadrajet.
The carb you have is a 4GC.
The carb model number is on a small three cornered tag attached to one of the air horn screws.
If it is missing, don't worry, most 4GC's take the same carb kit.
Just ask for a kit for a '61 Olds 4 barrel.
Here is a thread on re-building a 4GC carb.
Great thread and great tips. I am looking forward to rebuilding my first carb. Here is a pic of a kit I’m considering ordering from Fusicks. Seems correct!
Great thread and great tips. I am looking forward to rebuilding my first carb. Here is a pic of a kit I’m considering ordering from Fusicks. Seems correct!
You might want to give Daytona Carb a call. They sell kits for everything and are very helpful. While Fusicks may have the kit, I doubt you are going to get a lot of help from a sales person in you need it. They guys at Daytona Carb are very helpful. Here is the link.
Either the hairpin clips or the E-clips are fine to use.
One thing to be careful with on 4GC is the float bowl to throttle plate gasket. Different applications use different gaskets and they have different cuts and vacuum passages. Using the wrong one can make a 4GC get weird.
Use the one that matches any carburetor diagrams in the 61 shop manual, or if it's running well match the gasket to the one currently in it.
You'll find fine mesh brass screens in the fuel inlet and sometimes in the fuel crossover to the secondary float bowl. Be gentle with the brass floats; they're near unobtainium now.
First up, congratulations on your interest in your first carb rebuild. Not too many people do that these days, so I applaud you on the interest and willingness to jump in.
Couple things to know:
1) If it leaks gas _at_all_, it ain’t right. What I mean is when you first have it back on the car and are hoping it’s right, do a super, super careful review for any fuel leaks. Gas on a hot intake manifold can ignite and burn your car. Or worse. Any gas smell? Shut it right down.
2) Clean the h*ll out of it - scrub passages, use #0000 steel wool to get pits and grit off, then shoot any rotating pieces with your preferred lubricant. You’re looking for a smooth opening device that closes its butterflies the millisecond you let your foot off the gas. If you take your foot off and it doesn’t drop back to idle, something is off.
3) The basic operation of a carb is to use vacuum, springs, rods and jets to meter gas according to driver demand. In those days a heavy foot = low vacuuum; just off idle was fairly high vacuum. Put another way, vacuum is used as a proxy for driver demand. High vacuum = low demand; Low vacuum = high demand. Pretty much everything you do in between is making sure that the carb pulls the rods out of the jets when vacuum is low, and lets them rest almost closed when vacuum is high.
4) I’m no 4GC expert, but carbs are more or less a sandwich design: Airhorn: gasket: Main Body: gasket: throttle plate: gasket: intake manifold. The main thing is to make sure the non-gasket parts are flat (not bowed) to maintain vacuum seal (to provide a good vacuum signal to -well - more or less everything). And to be sure that no gas leaks out of the carb..
So, rebuild it on the bench, cleaning & polishing everything you can get at. Then mount it, but before you fire up the car - have a fire extinguisher at the ready just in case of fire. If you want to be really conservative, pull the coil-to-distributor wire so the carb gets full of gas, but the engine doesn’t fire. Then look for leaks. If you’re satisfied there are no leaks, then connect the coil wire & fire it up for real, extinguisher at the ready.
I don’t mean to sound overly conservative, but I fear gas fires a lot, so I hope this advice is useful to the courageous individual who wants to try, but safely.
First up, congratulations on your interest in your first carb rebuild. Not too many people do that these days, so I applaud you on the interest and willingness to jump in.
Couple things to know:
1) If it leaks gas _at_all_, it ain’t right. What I mean is when you first have it back on the car and are hoping it’s right, do a super, super careful review for any fuel leaks. Gas on a hot intake manifold can ignite and burn your car. Or worse. Any gas smell? Shut it right down.
2) Clean the h*ll out of it - scrub passages, use #0000 steel wool to get pits and grit off, then shoot any rotating pieces with your preferred lubricant. You’re looking for a smooth opening device that closes its butterflies the millisecond you let your foot off the gas. If you take your foot off and it doesn’t drop back to idle, something is off.
3) The basic operation of a carb is to use vacuum, springs, rods and jets to meter gas according to driver demand. In those days a heavy foot = low vacuuum; just off idle was fairly high vacuum. Put another way, vacuum is used as a proxy for driver demand. High vacuum = low demand; Low vacuum = high demand. Pretty much everything you do in between is making sure that the carb pulls the rods out of the jets when vacuum is low, and lets them rest almost closed when vacuum is high.
4) I’m no 4GC expert, but carbs are more or less a sandwich design: Airhorn: gasket: Main Body: gasket: throttle plate: gasket: intake manifold. The main thing is to make sure the non-gasket parts are flat (not bowed) to maintain vacuum seal (to provide a good vacuum signal to -well - more or less everything). And to be sure that no gas leaks out of the carb..
So, rebuild it on the bench, cleaning & polishing everything you can get at. Then mount it, but before you fire up the car - have a fire extinguisher at the ready just in case of fire. If you want to be really conservative, pull the coil-to-distributor wire so the carb gets full of gas, but the engine doesn’t fire. Then look for leaks. If you’re satisfied there are no leaks, then connect the coil wire & fire it up for real, extinguisher at the ready.
I don’t mean to sound overly conservative, but I fear gas fires a lot, so I hope this advice is useful to the courageous individual who wants to try, but safely.
Best of luck
Chris
Gosh thanks for all that Chris. I found it strange that it started leaking all of a sudden the other day, out of nowhere. Never had one leak prior to that. After re routing my fuel lines to the carb from the filter, I would drive and pull over periodically to inspect for any fuel leaks. I never saw any, anywhere on the carb or the fuel line fittings. Wondering what could make the carb start dripping fuel like it did the other day. Guess things just go bad sometimes eh?
You might want to give Daytona Carb a call. They sell kits for everything and are very helpful. While Fusicks may have the kit, I doubt you are going to get a lot of help from a sales person in you need it. They guys at Daytona Carb are very helpful. Here is the link.
When carbs start leaking out of nowhere, it’s trouble shooting time. As in, don’t drive it. Gas on a hot intake manifold is a bad combination. Imagine it catches fire and burns up your engine wiring, or the whole car. You don’t want that. Been there.
Your game now is to clean the living h*ll out of it. Get a 5 gallon bucket of Berryman’s carb cleaner. Dunk everything metal for a few days. Don’t dunk anything plastic or Bakelite. Then spend a few days cleaning every, every passage with tiny wires or pipe cleaners. Dig around here and other GM websites for rebuilding advice. It’s not complex, but you have to get things sealed or there’s danger.
With carbs cleanliness really is next to godliness. And I’m not religious. Carbs deeply depend upon carefully measured & metered passages to send just the right amount of air/gas to the engine. If there’s dirt in the passages or they’re blocked entirely, it throws that air/gas balance off. Or can cause leaks…
After a good few-day soak, rebuild the carb, then install, and have an extinguisher near by when testing. And keep the extinguisher in the car on its shake down cruise / aka maiden voyage. And probably thereafter.
I’ve rebuilt maybe 20 or so qjets, which were a later _different_ design from the 4GC, but the sandwich principle holds in my view You can do this, just be safe about it.
When carbs start leaking out of nowhere, it’s trouble shooting time. As in, don’t drive it. Gas on a hot intake manifold is a bad combination. Imagine it catches fire and burns up your engine wiring, or the whole car. You don’t want that. Been there.
Your game now is to clean the living h*ll out of it. Get a 5 gallon bucket of Berryman’s carb cleaner. Dunk everything metal for a few days. Don’t dunk anything plastic or Bakelite. Then spend a few days cleaning every, every passage with tiny wires or pipe cleaners. Dig around here and other GM websites for rebuilding advice. It’s not complex, but you have to get things sealed or there’s danger.
With carbs cleanliness really is next to godliness. And I’m not religious. Carbs deeply depend upon carefully measured & metered passages to send just the right amount of air/gas to the engine. If there’s dirt in the passages or they’re blocked entirely, it throws that air/gas balance off. Or can cause leaks…
After a good few-day soak, rebuild the carb, then install, and have an extinguisher near by when testing. And keep the extinguisher in the car on its shake down cruise / aka maiden voyage. And probably thereafter.
I’ve rebuilt maybe 20 or so qjets, which were a later _different_ design from the 4GC, but the sandwich principle holds in my view You can do this, just be safe about it.
Chris
I appreciate all the support from you and everyone on this thread. Means a lot and there’s TONS of good advice / tips from all you experienced Olds guys.
I’ll check into that Berryman’s. Cans of compressed air vs using an air compressor is best?
When carbs start leaking out of nowhere, it’s trouble shooting time. As in, don’t drive it. Gas on a hot intake manifold is a bad combination. Imagine it catches fire and burns up your engine wiring, or the whole car. You don’t want that. Been there.
Your game now is to clean the living h*ll out of it. Get a 5 gallon bucket of Berryman’s carb cleaner. Dunk everything metal for a few days. Don’t dunk anything plastic or Bakelite. Then spend a few days cleaning every, every passage with tiny wires or pipe cleaners. Dig around here and other GM websites for rebuilding advice. It’s not complex, but you have to get things sealed or there’s danger.
With carbs cleanliness really is next to godliness. And I’m not religious. Carbs deeply depend upon carefully measured & metered passages to send just the right amount of air/gas to the engine. If there’s dirt in the passages or they’re blocked entirely, it throws that air/gas balance off. Or can cause leaks…
After a good few-day soak, rebuild the carb, then install, and have an extinguisher near by when testing. And keep the extinguisher in the car on its shake down cruise / aka maiden voyage. And probably thereafter.
I’ve rebuilt maybe 20 or so qjets, which were a later _different_ design from the 4GC, but the sandwich principle holds in my view You can do this, just be safe about it.
Chris
I appreciate all the support from you and everyone on this thread. Means a lot and there’s TONS of good advice / tips from all you experienced Olds guys.
I’ll check into that Berryman’s. Cans of compressed air vs using an air compressor is best?
I use cans of compressed air for computers & keyboards. Didn’t have a cheap compressor until at least age 55. I was probably late to the compressor party.
If you can justify it in your budget, you’ll find a small compressor very handy at home for volleyballs, basketballs, inflatable pool toys, inflatable beds, car tires, wheel barrow tires, blowing winter/summer dust out of cars and a bunch of other uses. It’s one of those tools that, once you have it, there are tons of uses you discover.
I’ve got a small cheap one and it’s been great to pump up the neighbor’s tires as a courtesy to save them a trip to the gas station….
I use cans of compressed air for computers & keyboards. Didn’t have a cheap compressor until at least age 55. I was probably late to the compressor party.
If you can justify it in your budget, you’ll find a small compressor very handy at home for volleyballs, basketballs, inflatable pool toys, inflatable beds, car tires, wheel barrow tires, blowing winter/summer dust out of cars and a bunch of other uses. It’s one of those tools that, once you have it, there are tons of uses you discover.
I’ve got a small cheap one and it’s been great to pump up the neighbor’s tires as a courtesy to save them a trip to the gas station….
Cheers
chris
Got it. I do have a small pancake air compressor, I’ll use a jet nozzle for blowing out parts after cleaning. I’ll turn down the working pressure of the nozzle. Thanks for all the input Chris, much appreciated. Going to give Dayton a call tomorrow to see about getting a rebuild kit on order. Back to the 50’s car show at the fairgrounds is June 21, 22, 23 here in MN. Gotta be ready.
Forgot you had ancient iron (4GC). Attached (see .pdf attachment) is a tasty clean readable copy of Delco Rochester Models 4G & 4GC including Adjustment Procedures for the 4G & 4GC. Might be handy to print it out.
Forgot you had ancient iron (4GC). Attached (see .pdf attachment) is a tasty clean readable copy of Delco Rochester Models 4G & 4GC including Adjustment Procedures for the 4G & 4GC. Might be handy to print it out.
Lots of good info for you to get the job done. This is the kit I got from Daytona 1132. My carb # is 7019050. It looks like someone plugged the idle vent tube but that's about the only difference.
The reason for the leak was probably due to the needle on the floats not seating and caused it to flood.
When you are ready, take a pan of boiling hot water and submerge your floats in it to check for leaks. The heated air inside the float will want to escape and if there are any holes will show as bubbles in the water. Rebuild kit 1132 from Daytona Parts for carb 4gc # 7019050
I didn't see this mentioned so if it already has been sorry. As I understand it there is a possibility that the throttle body holes where the primary and seconday shafts ride wear out. Besides the possibility of causing the shafts to hang up there is also the chance of air to leak through them so pay attention to that.
Just saw rocketraider said this in post #17, it matters.
Keep every gasket intact as much as possible during disassembly and do not discard them. Open the kit and find the gaskets that match the old ones exactly, lay the old gasket on the new one and hold them up to light to confirm all of the holes are the same, then turn it over confirm from the other side. Take any gaskets that are not an exact match out of the work area.
One mismatched hole in a gasket can block a port/passage and take you way down a rabbit hole to diagnose a drivability issue...been there.
Just saw rocketraider said this in post #17, it matters.
Keep every gasket intact as much as possible during disassembly and do not discard them. Open the kit and find the gaskets that match the old ones exactly, lay the old gasket on the new one and hold them up to light to confirm all of the holes are the same, then turn it over confirm from the other side. Take any gaskets that are not an exact match out of the work area.
One mismatched hole in a gasket can block a port/passage and take you way down a rabbit hole to diagnose a drivability issue...been there.
Also, they aren't cut perfectly and change over time slowly becoming different from the first template the used.
Question: is there ever a need to use blue loctite on an screws / bolts when re assembling a carb?
I've never used any on auto carburetors & I don't know if it's needed, sorry. I've used Loctite Oil & Gas Resistant product on some stuff which routinely gets oil & gas on parts like lawn mower engines, generator carburetors & stuff. That stuff works really good.
LOCTITE 1252795 Oil & Gas Resistant Adhesive Sealant
Question: is there ever a need to use blue loctite on an screws / bolts when re assembling a carb?
No, never.
It could possibly get into the wrong place and gum things up.
The same thing goes for any gasket sealer.
I might add, most screws have lockwashers.
Make sure they go back in place when reassembling.
Last edited by Charlie Jones; May 13, 2024 at 07:59 AM.
(1) Read the .pdf file I sent you to gain an overview;
(2) Have ready an assemblage of small containers to hold/contain parts;
(3) Sharpie marker pen to label the containers;
(4) Pen/Pencil/Notepad to scribble;
(5) Various tools, carb. cleaner, etc.
During disassembly. A clean, organized work environment is key. A towel laid under the carb. on the work surface is extremely handy. A towel will catch the check *****, needles, clips etc. you drop from running off the table onto the ground never to be found again.
(1) Methodically follow the disassembly instructions in the .pdf file;
(2) TAKE PICTURES
(3) Accurately label each part. Some will/might appear identical (e.g. check *****, etc.). Make liberal use of pen/pencil notepad;
(4) Be patient - don't rush.
I just want to say thank you all, for the advice/input/suggestions. It means a lot to me to be supported by experienced gearheads like you all. Carb kit is on order, I expect it to be here this week so I can start in on this first rebuild! 🤞🏼
