Hello everyone! I have an oddly specific issue to ask about. Today I drove my '70 Buick GS 455 about 40 minutes to school and back. It has a quadrajet and as far as I know, the block is a '72 with stock internals (I think it has about 72k miles on it), it has always (and does) run really well. The trip out was perfectly fine and I had no issues whatsoever. On the way home however I encountered an interesting issue about 3 or 4 times. I was cruising along at about 55-58 mph on a country back road when all of a sudden, it seemed as though the smell of gas was really pungent so I thought I might be running rich, but I wanted to continue to baby the car along to see if it might have just been that one time. Not specifically when I was smelling gas, the car would act as if I took my foot completely off the gas. It would kind of "woah" or slow down, at some points. It wouldgive a little resistance, and it felt as though I was going from WOT to absolutely none whatsoever. I have full diff fluid and I checked before the trip. Full transmission fluid, full on fresh oil, running at good temps. I've never encountered the car running like this before and I'm not sure what the issue is. As soon as I went down to about 45-50 mph (2100-2200RPM) and went back up to around 55 (2300-2370ish RPM) it went away. I think it might be an issue with the carb, but I'm not completely sure. I haven't rebuilt it, but as far as I know, it sat for about a year before I bought it from the seller. Any tips or advice would be appreciated. If its a carb issue, I have a 750 spreadbore double pumper on standby
First, the Q-Jet is a much better carb for your 455. The Holley would just make it use more fuel and it would make the car slower. Not enough data to figure out what's going on. "Test, don't guess!" Is it a fuel issue? We need to know the fuel pressure when the issue is happening. Run a pressure gauge to the windshield and see if you can duplicate the problem. Are you sure your tank wasn't low and exposed the pick up tube? Rubber lines off the tank and pump in good shape? Lots of questions before any real answers
Strong smell of gas and stumble could be flooding or loading up. Do you notice black, sooty smoke out the back when it fires back up?
I would say the float might have gotten stuck and fed too much gas and started to flood out and that is why you smell gas or the ignition is cutting out and engine is still feeding gas so you smell it. if you have points and such make sure that part of the system is working and set properly then make sure timing is correct. If you smell gas you either have a leak in a hose and running out of gas so you smell it when it all moves again. There again, check all rubber lines going to carb and back. There is a spot under the drivers door where the lines are connected with a rubber hose might be a leak there, I had it on my 71 350 might be different on yours. Also could be the choke has come apart and is closing when at that speed and rpm, look at that make sure it is not closing when warm.
Noted about the carb. It was kind of a worst case sorta deal. I will pick up a fuel pressure gauge sometime today or tomorrow and see if I can get the same issue to happen again. I filled up that morning, so I don't suspect it was an almost empty tank issue. I have checked the rubber lines and they look decent, but I should probably go through and replace those today. I just need to get some. Should I get 5/16 or 3/8?
Sounds like momentary flooding that cleared up on it's own. The float/needle-seat, stuck for a bit, flooded the carburetor, and caused the smell, and symptoms. When was the last time the carburetor was rebuilt?
Could be just a fluke in the carb although kind dought it..... I would look into rebuilding it just because...... BTW what is the part number on the carb... But in the meantime I would be looking into the ignition system...
Be careful with just a visual inspection, the outside looks ok, the inside could be delaminated, which is what happened to mine with the line under the drivers door on the frame, it was getting sucked closed
All of the above and make sure the choke flap is hooked to the thermostat spring. I had a intermittent problem on a qjet before , very similar to this and the rod had come loose and at certain velocity it was pulling choke door closed. But yeah , it could be a lot of things already mentioned.
How long have you owned the car? Surprised no one has mentioned clogged fuel filter. Had an issue with this happening once. At highway speeds, with steady throttle, the car would nose over, I'd lift off the throttle, it'd go to idle, I'd ease back into it, and it would pick back up and go until the float bowl ran out, lift off and repeat it all over again. I kept replacing the fuel filters in the carb, and it eventually quit giving me problems. Clogged fuel filter. If the car has been sitting awhile, there may be crud in the tank/lines, and a big enough piece made your inlet needle/seat get stuck open, flooded it out, until it cleared, and then you were on your way.
