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There's a lot of interesting suggestions here, but going back to your original post/description, you say that you can see fuel down the throat of the carburetor? Are you seeing some fuel down there when the engine dies? You really shouldn't be seeing any fuel down there unless the float bowls are overflowing. I get the fact that the accelerator pump will squirt a little fuel into the throat but it should be pretty miniscule and after the car starts you shouldn't be seeing any raw fuel down there.
On my 1954 Olds Super 88 my needle/seat was sticking in one of the float chambers after a rebuild. It exhibited a very similar symptom to what you describe. When cold, the engine loved that raw fuel but when hot, that overflowing float chamber flooded the engine.
When I look at your carburetor from the photo you posted, it doesn't look very clean. I think you said that you rebuilt it but if so, it should look pretty sparkly clean if it was done properly. On cars this old, it's imperative that you strip all the parts off of the body and use an ultrasonic cleaner to clean everything, including the carb body. There is no other way to clean the interior ports/passages of old varnished, hardened, material. Dipping in carb cleaner just doesn't work unless you are able to give all those interior ports/passages a scrubbing (which only an ultrasonic will do, with proper cleaning solution for ultra-sonics...DONT use anything with a flash point in an ultrasonic). Harbor Freight offers a fairly inexpensive one that almost the entire 4-Jet body will fit into. It has the side benefit that you can also clean your wife's jewelry with it ;-)
Until I did this, my first rebuilt of my carb just didn't work. I had to do it all over again, this time tearing it down more fully and ultra-sonic cleaning EVERYTHING.I then followed the service manuals instructions for setting everything, including the float levels, choke cam, secondary cam. After mounting back on the car I have to make some choke adjustments at "cold" and "hot" a few times. After that, the car ran like new.
No I haven’t looked down the throat while the engine is running. But even if I see that fuel sitting there shouldn’t the cylinders be pulling it down? Now when I start it it tries to pop off right away but doesn’t until I pump the gas a bunch while cranking. And that pic of the carb is very old I’ve rebuilt it and cleaned and my floats never not work. They stop the fuel coming in right when they get level. I didn’t know the measurements so I just guessed. When I get the book I’ll do another rebuild. I saw that ultrasonic cleaner yesterday at harbor freight, maybe I’ll try to get it for my next rebuild. For now I got compressed air
No, it won't pull it down into the cylinders (unless you dump like pint/quart down its gullet). The excess fuel will rest in all the little recesses of the intact manifold and the cylinders will pull in the vapors of the evaporating fuel. I sometimes pour a few ounces of raw fuel into the carburetor throat when it hasn't run in quite a while rather than using start fluid. Starter fluid can pre-ignite before the spark plug fire on high-compression engines causing rods to get bent (or worse). These 1954 324 engines usually don't pre-ignite starter fluid, but I just avoid it to be safe.
Anyway, if one of the float chambers is overflowing you'll get the effect you described, including seeing wet plugs. The engine will suck the vapors from the pools of fuel in the intake manifold cavities along with the additional fuel from the carb jets creating an overly rich environment that will cause the engine to act like it's flooded when warmed up. When cold, the engine likes those extra little pools of fuel down inside the intake manifold.
I'm not saying this is your problem, but if you are still seeing wet sparkplugs and wet fuel down the throat of the carburetor, that's where I would start looking because that ain't right.
That definitely makes sense and I really need to pull my carb and adjust the foals correctly and boil out all old sediment. And get the correct accelerator pump or bend the rod on mine till it shoots fuel right on spot. But today I got my own timing gun and set the timing and used the vacuum gauge to set AF mixture and it’s running a lot better, and it fires right up now! But I went for a test drive and it was pretty good minus the hesitation in the accelerator pump, but I went up a small hill at about 25mph stomped on it and it just kept barely going, when I stepped on it it did nothing to the engine. After that I took a video of me accelerating in park but I don’t think it will load on this site
You reported a very low vacuum reading. The vacuum reading needle must be rock steady - it cannot drift up/down more than a mouse turd - understood? Rock steady. I said how to perform the test in the other post (top LH column of the diagram). If you fail that test you have an issue with vacuum. If you do not have a rock steady vacuum gauge needle you have a vacuum issue.
What is your CURRENT intake manifold vacuum in inches of Mercury?
I did perform that test, you said to hook in the line that goes from the back base of my carb going to the wiper motor, that’s what I did. And 14 of 15 was the highest reading I got before the AF screws would come all the way out. Am I missing something?
Yeah Ha Ha. Well it didn’t pass the test then. Let’s take a step back, I don’t have the ultrasonic cleaner. Can I boil my carb over a stove in anything specific like cleaners or something?
Chris - Slow down just a tad. The intake manifold is the number one device which supplies the air fuel combustion mixture to every cylinder in your engine. That's its purpose. It has this really huge hole in the top of it where you supply the air fuel combustion mixture - called the carburetor. You CANNOT supply a nominal (optimal) supply of combustion mixture if you have inadequate delivery of that air fuel combustion mixture. Measuring and accounting for any anomalies in the vacuum measurements is a requirement to satisfy air fuel mixture delivery via the carburetor. You can't dump fuel in the carburetor and expect it to operate at idle, cruise and WOT. It is imperative your air fuel combustion mixture delivery is optimum.
You said your vacuum gauge was not steady. Honestly, that means absolutely nothing to anyone. Communication is vital. WHAT is the amount of variance of your vacuum gauge reading e.g. between what two points in inches of Mercury?
Yeah Ha Ha. Well it didn’t pass the test then. Let’s take a step back, I don’t have the ultrasonic cleaner. Can I boil my carb over a stove in anything specific like cleaners or something?
Thats only other thing I can think of to make my carb better. The most I’ve done to it is shoot carb clean through every passage and hole on the carb and base plate.
Think about this a minute. If you "step" on the gas, and the car goes nowhere but it idles satisfactorily - exactly what is it which happens when you "step" on the gas pedal? You're delivering air & fuel. That mixture needs to be correct. If you can't supply the correct air fuel mixture when you hit the pedal you're dead in the water. Your issue might be anywhere - but, the simple fact is you have to identify if you can deliver the appropriate A/F combustion mixture at idle, cruise & WOT. That is the purpose of measuring and accounting for any issues with air fuel delivery. That's why you're measuring intake manifold vacuum.
OK. It appears, thus far, you aren't following along on the importance of the diagram I provided to you; therefore, I'll post the exact same diagram again for you here in this post. Read every single item in this diagram and pay particular attention to the readings regarding an unsteady vacuum needle. Then, we can move forward with helping to identify where the issue might be. Yes, the assumption is you have all the rubber hoses connected, no cracks, tight fittings, clean carburetor. If you cleaned it once and you're satisfied with the cleaning there's no need to clean it again. You should probably wait for your manual and look at the diagrams of the hose routing.
When the car really warmed up it jumped from 13 to 15 inches in mercury
That reading is far too low and the fact it's jumping around indicates you most likely have two issues: (1) Bad, cracked vacuum hoses, or the hoses are not hooked up or plugged correctly to form a good tight "system" of air fuel combustion delivery; and, (2) your A/F mixture is not set correctly. The reading needs to be "steady" and definitely above 15"Hg. You should be able to achieve ~17"Hg minimum.
Ok I screen shot the diagram and will follow it when I hook my gauge again. I have no broken hoses because I only have one metal line going to the distributor that is it. And the metal line sticking out the back for the wiper motor which is never hooked up. Is there anything else than can affect this air fuel issue, the way my idle is set? I think I’ll just start from scratch on the carb pull it off and clean. Like I asked earlier. What can I do I to clean it without the ultrasonic thing, can I boil it in something?
Like I asked earlier. What can I do I to clean it without the ultrasonic thing, can I boil it in something?
I've rebuilt a dozen or more carbs - I've never used an ultrasonic cleaner, I've never boiled a carburetor & I've never used electrolysis (to remove rust generally) for a carburetor. I soak the snot out of them with PB Blaster then another snot soaking of Carburetor Cleaner each time I leave them soak overnight before I use my carburetor brushes to clean out passageways, etc. I routinely use compressed air in all passageways & throughout the carburetor. That's all I do. I think an ultrasonic cleaner is a great idea - I have never found the need but I'm sure they work great. I used to have one for small metal items. You said (above) you rebuilt the carburetor, already. Not sure why you want to do another rebuild. Unless, you "think" you did a rebuild but really didn't do a rebuild. You can buy a rebuild kit for a 4GC carburetor which includes gaskets, accelerator pump, springs, etc. Depending on what's in the kit, they run between $45 - $75.
DO NOT boil anything which is flammable. Crackheads might be good at it - but most are not.
Cleaning brushes are ~$3 - $5 on Amazon - probably more at the auto parts store. Big box stores might also have them (if you think you want to get a set, maybe Ace, Lowe's, etc.).
So by stepping on the gas going no where, does that mean it’s getting more air than fuel?
If vacuum is the issue, that's why you're measuring your vacuum, it could be one (too much fuel, not enough O2) or the opposite (too much air, not enough fuel). Think about what your plugs looked like. You said they were wet. They aren't wet from too much air.
Ok I screen shot the diagram and will follow it when I hook my gauge again. I have no broken hoses because I only have one metal line going to the distributor that is it. And the metal line sticking out the back for the wiper motor which is never hooked up. Is there anything else than can affect this air fuel issue, the way my idle is set? I think I’ll just start from scratch on the carb pull it off and clean. Like I asked earlier. What can I do I to clean it without the ultrasonic thing, can I boil it in something?
Look. The fuel pump and the vacuum container/pump/box on your beast uses a hose - you've been down this path before. If they were supposed to be "connected" to the carburetor and they are "not" connected to the carburetor then those ports on the carburetor should be plugged to create a sealed system. I said this before, the 4GC carburetor is NOT in my wheelhouse of knowledge. I just don't know that particular carburetor and I don't know where the vacuum hoses connect on a 1955 Olds 88. We've been down this road several times in the other thread. This is "WHY" you should read the manual.
On my 1954 Olds Super 88 my needle/seat was sticking in one of the float chambers after a rebuild. It exhibited a very similar symptom to what you describe. When cold, the engine loved that raw fuel but when hot, that overflowing float chamber flooded the engine.
This is good info and aligns with the link I just provided (above).
Look. The fuel pump and the vacuum container/pump/box on your beast uses a hose - you've been down this path before. If they were supposed to be "connected" to the carburetor and they are "not" connected to the carburetor then those ports on the carburetor should be plugged to create a sealed system. I said this before, the 4GC carburetor is NOT in my wheelhouse of knowledge. I just don't know that particular carburetor and I don't know where the vacuum hoses connect on a 1955 Olds 88. We've been down this road several times in the other thread. This is "WHY" you should read the manual.
Crack heads haha. Ok pb blast soak and carb cleaners. For some reason there’s no open ports on my carb, all there is is the two lines I’ve said before. Hints why the fuel pump top lines that make the wipers work are open and I’m ok with it for now because nothing on the carb is left open. I actually would like to figure out how use the plugged holes on the carb but that’s a later discussion on a different thread.
Have you run a compression check on your cylinders as yet? What you describe is what burnt valves sound like when leaking, popping back through the carb. Hard starts when hot, plugs that are of a different color on the same bank also. If we could hear it run or even crank over, a lot could be learned A compressing tester can be rented, loaned for free from most parts houses. You are maybe chasing your tail with a low compression ill engine, many of the systems you described could be from burnt valves. You have so many issues going on at the same time, it's hard to keep up. I personally don't believe you have a vacuum problem, but it is something you will have to sort out later sometime...Tedd
Tedd provides a valid point. A low vacuum reading doesn't necessarily mean a vacuum leak, it can also mean low &/or no compression on one or more cylinders due to burned valve(s). The diagnostics you're performing are not w/o merit. Your vacuum readings between 13"Hg - 15"Hg is considered low. If the vacuum gauge needle wavers & flutters ~1"Hg - 3"Hg instead of remaining steady, and you are unable to raise vacuum above 15"Hg with a steady needle reading, it's time to look elsewhere.
An engine compression gauge costs anywhere from $20 - $100. Most members own one. You're beginning to get your feet wet w/ diagnostics, diagnosing issue(s) is the first step in making informed decisions leading to correct resolution(s).
Well yesterday I bought a timing gun and reset the timing from how I did it a few weeks ago. When I did it yesterday my top dead center was off about an inch from my last mark. The valves didn’t look bad when I had the heads off. And as of yesterday fixing the timing and adjusting the carb it fires right up with the engine cold or hot so I don’t see how I could have low compression. I’m not saying my valves are good but I’ll see what I can do this week about a compression gauge. When I had the heads off a few weeks ago I didn’t dare touch the valves in any way. Inside the cylinders looked good I thought, very clean no pitting. I could be wrong but I feel more confident on the valves and compression than I do on my carb since I’ve never rebuilt it properly. And like I’ve been told on here before, exhaust all means on easy stuff before getting into tearing the engine down.
Well yesterday I bought a timing gun and reset the timing from how I did it a few weeks ago. When I did it yesterday my top dead center was off about an inch from my last mark. The valves didn’t look bad when I had the heads off. And as of yesterday fixing the timing and adjusting the carb it fires right up with the engine cold or hot so I don’t see how I could have low compression. I’m not saying my valves are good but I’ll see what I can do this week about a compression gauge. When I had the heads off a few weeks ago I didn’t dare touch the valves in any way. Inside the cylinders looked good I thought, very clean no pitting. I could be wrong but I feel more confident on the valves and compression than I do on my carb since I’ve never rebuilt it properly. And like I’ve been told on here before, exhaust all means on easy stuff before getting into tearing the engine down.
there’s no more low popping since I adjusted timing yesterday. I guess I had it to high and that’s when it didn’t want to start.
there’s no more low popping since I adjusted timing yesterday. I guess I had it to high and that’s when it didn’t want to start.
so let’s get back on track one step at a time. The carb needs a real rebuild and I need to check compression. And mind you it’s 20 degrees temp out here and it will fire up, so does that mean bad compression? I thought it meant good compression
Chris - You're adding information which hasn't existed in previous posts (at least I've missed it). You're saying you adjusted timing again. When you say you feel more confident on compression, not clear how that can be validated without compression readings.
so let’s get back on track one step at a time. The carb needs a real rebuild and I need to check compression. And mind you it’s 20 degrees temp out here and it will fire up, so does that mean bad compression? I thought it meant good compression
We are on track. Your vacuum readings are low and the gauge needle is not steady. If you can't achieve a steady vacuum reading above 15"Hg you have an issue. The fact it starts in any weather is not an indication of any compression reading value. Either you measure compression or you don't.
"If" you elect to perform a compression test, you should perform the compression test both dry & wet. I'm not completely certain what the normal compression range is for your specific engine. Based upon age, I'd suspect somewhere ~120psi - 130psi, perhaps. Anything below 100psi on any cylinder is a complete fail. Taking engine cylinder compression readings is fundamental to understanding the basic health of your engine.
My compression readings - 1971 350 cid 125k miles.
We are on track. Your vacuum readings are low and the gauge needle is not steady. If you can't achieve a steady vacuum reading above 15"Hg you have an issue. The fact it starts in any weather is not an indication of any compression reading value. Either you measure compression or you don't.
it should indicate something since a car won’t start without compression. And I’m not saying I won’t test it. I said I’ll see about getting a compression gauge this week. I’m assuming “wet” means when warm and “dry” means when cold? Is the compression test how you check valves as well?
January 7th, 2024, 08:51 AM
