Mr.Smooth

Hey guys. I got a 68 442 with a qjet. Ok so its winter here in pa and i dont drive my car in cold weather, so i put fuel stabilizer in each year before it sits in the garage. I do start it occasionally to get some oil circulated. Since its 60* out today, i decided change the fuel filter and take it for spin around town. I got a filter from autozone with the the check valve. I put the check valve facing away from the carb. I started it up, ran and idled perfect for about 10 min. I pulled the car out to go for a drive. Heres the problem, about 5 min into the drive, when i would come to a stop, the idle was very low, 3-400rpm, couldnt tell cuz tach was jumping. I pulled over and turned the idle screw up about 1/2-3/4 turn to get around 6-700 in park. After i left the store it seemed to idle a bit higher for a few seconds after letting off the gas. I also thought i heard the rpm surging a bit? Fuel pump is only 4 years old.
It also had an odd smell to it. I dont remember that smell after using fuel stabilizer?

My only thoughts are maybe a clogged jet and or a mix off old gas with stabilizer?

Thoughts??

Thank you

Vintage Chief

If knew the dwell & timing were set correctly, the 1st thing I'd check is ea. A/F mixture screw is set to highest achievable vacuum & I can achieve a rock steady needle on the vacuum gauge. You might consider removing the check valve from the filter and see if that clears up the condition. The check valve can easily be removed w/ your fingernails or a needle-nose pliers. Possible the actual valve isn't working correctly or misaligned somehow.

Olds64

I'd get 5 gallons of premium fuel and add it to the tank. I've had poor idle quality in the past because of old gas.

Vintage Chief

Jesse - Good suggestion. I'd fill the tank w/ premium from a reputable gas station.

deadeyejedi

x3 on the good fuel i would also double check that you dont have a sticky choke, maybe its not opening all the way

Sugar Bear

Here is my guess ... changing the fuel filter caused a piece of metal swarf or dirt to get between the needle valve and seat causing some flooding. Pinch the rubber supply hose to the fuel pump closed, start the car and run it out of fuel. Now the fuel bowl will be empty and the needle will be off the seat. Release the clamp and crank the engine to start it, while cranking the fuel pump will be surging and pulsing fuel to wash the needle and seat clean. This may need to be repeated a few times.

Vintage Chief

If during storage of the new fuel filter after manufacturing & prior to shipment to a customer, a mouse may have dropped a turd anywhere inside that fuel filter. You just don't know about mice.

jaunty75

THIS!!!

Everybody is talking about using different fuel or adjusting the timing or whatever. WHY? You changed the fuel filter, and now you have a problem. As counterintuitive as it might seem, look to what you just did as the cause!!

One time I changed the fuel filter on my '67 Delta 88, and the car started to lose power at highway speeds, almost stalling out sometimes. I thought there might be a problem with the new fuel filter, so I changed it again. To my surprise, the previous new filter I had just installed was dirty! The process of changing the filter, which involved unscrewing the metal line from the pump to the carb and shaking that thing around, stirred up dirt and crud which got transported up to the filter and clogged it up. Changing it again fixed the problem, and it never recurred.

Let's back up to the very beginning. WHY did you change the filter before setting out on your drive? Was there a problem prior to changing it, or did you do it just for the heck of it or because you felt it had been long enough that changing it would be a good idea?

Carlarena1

I cannot use the filter with the check valve, as it causes the same problem you are referring to. Like Vintage Chief suggests, i would remove the little rubber check valve by pulling it straight out of the filter. They are know to cause restrictions and problems.

Sugar Bear

Are filters without the valve NLA? If they are, they have a gasket on the end to prevent fuel from bypassing the filter.

Mr.Smooth

Yea it has quite a few years since it was changed lol

442Harv

My son has a 68 also. He changed his filter, with a check valve also, and his would not start. Took out the check valve, and fired right up.

Vintage Chief

Yes, they are available:

https://quadrajetparts.com/-a-28.html

Sugar Bear

TY Norm, That is the correct filter and gasket/rings.

Fun71

Available from your local auto parts store.


https://www.napaonline.com/en/p/FIL3048
Part #: FIL 3048
Line: NAPA Filters

z11375ss

Sounds like it needs a 4 speed. Just my guess. JK, I would go with what did you change? Go back to that.