Spuddering at W.O.T
July 19th, 2016, 10:01 AM
#1
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Join Date: Oct 2013
Location: Clinton Twp, MI
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Spuddering at W.O.T
My 72 350 4bbl car has developed a spudder when at wide open throttle. It is running a qjet carb. Car idles and runs great under normal driving and when parked revs well. The carb check out fine with a clean filter, good working power piston and accelerator pump. With that being done where do you think the problem lies? Possible sending unit? or fuel pump?
Thank you,
John
Thank you,
John
July 19th, 2016, 01:03 PM
#4
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Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,763
Fuel issues:
fuel pump failure
secondary metering rod fell off hanger
air bleed tube fell out of air horn after a rebuild
Ignition issues:
resistance wire to distributor had corroded terminal
spark plug wire disconnected (idled and ran fine, had a WOT miss/power loss)
These are just some of the things that can cause an issue. If you can provide more info on exactly what is happening and when it happens that may help with diagnosing the problem.
July 19th, 2016, 01:44 PM
#6
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Join Date: Oct 2013
Location: Clinton Twp, MI
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That is not a lot to go on. I have experienced a lot of issues with rough running at WOT and some were fuel issues and others were ignition.
Fuel issues:
fuel pump failure
secondary metering rod fell off hanger inspected carb and everything checked out
air bleed tube fell out of air horn after a rebuild
Ignition issues:
resistance wire to distributor had corroded terminal New distributor and coil along with wires and plugs 1 year ago
spark plug wire disconnected (idled and ran fine, had a WOT miss/power loss) checked all plug wires at dist and plugs all on tight.
These are just some of the things that can cause an issue. If you can provide more info on exactly what is happening and when it happens that may help with diagnosing the problem.
Fuel issues:
fuel pump failure
secondary metering rod fell off hanger inspected carb and everything checked out
air bleed tube fell out of air horn after a rebuild
Ignition issues:
resistance wire to distributor had corroded terminal New distributor and coil along with wires and plugs 1 year ago
spark plug wire disconnected (idled and ran fine, had a WOT miss/power loss) checked all plug wires at dist and plugs all on tight.
These are just some of the things that can cause an issue. If you can provide more info on exactly what is happening and when it happens that may help with diagnosing the problem.
July 19th, 2016, 04:32 PM
#9
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Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 13,763
I have experienced something similar to that as well, after doing a long burnout the engine would fall flat at the top of 1st gear, then recover after shifting to 2nd. No problem if I didn't do a long burnout, so it seemed like a fuel starvation issue. Any idea what fuel pump you have on the car?
July 19th, 2016, 07:20 PM
#10
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Join Date: Aug 2013
Location: Evansville, IN
Posts: 10,284
All that carb rebuild really makes me suspect it, actually.
Please describe the specific WOT activity. I had plugged secondaries and mine would go like a bat out of hell, but would not go above 65 mph on the road, even to cruise. It would surge.
When you are flooring it, are you at highway speed, or just launching from a light, or doing 30 or so? Secondaries are not involved in flooring it at lower speeds, even though the throttle is open, the air valves are not.
Does it surge on you, like if you were to punch the gas every second, or does it really fall on its face for many seconds? I think an inadequate fuel pump and an empty bowl makes you fall off for more than just a second, but others will have to confirm that.
Please describe the specific WOT activity. I had plugged secondaries and mine would go like a bat out of hell, but would not go above 65 mph on the road, even to cruise. It would surge.
When you are flooring it, are you at highway speed, or just launching from a light, or doing 30 or so? Secondaries are not involved in flooring it at lower speeds, even though the throttle is open, the air valves are not.
Does it surge on you, like if you were to punch the gas every second, or does it really fall on its face for many seconds? I think an inadequate fuel pump and an empty bowl makes you fall off for more than just a second, but others will have to confirm that.
