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Unexpected surging

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Old 11-19-2016, 09:04 PM
  #1  
shenango
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Default Unexpected surging

Today it snowed all day in N/W Pennsylvania. Yesterday it was 72* and sunny, a perfect day for an end of year romp in the "75. I left at noon and toured the country side in PA and Ohio with every turn adding another 15 minutes to my outing. The recent build on my Qjet was working flawlessly and in combination with my new distributor has eliminated the surging I had been fighting all summer. I was banging gears and grinning for 3 full hours. At the end of my trip I stopped at my local fill em up station and topped off the tank with 91 octane non ethanol and a half pint of Sta-Bil to get ready for the long winter. Even before I left the lot the car was bucking like a green pony. If I had been a couple of miles down the road I would say it is bad gas but I was just pulling away from the pump when it happened. My trip home was about 10 miles and by the time I got home the surging was not as bad as at the station but still there. Could my intake and carb have heated up enough to cause the problem while sitting without the engine running or should I look somewhere else? It was definitely not the end I was hoping for on my last ride of the year. Any ideas are welcome, Thanks in advance.
Jerry
Old 11-19-2016, 09:37 PM
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cv67
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St. Jude Donor '05

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woulda p'd me off about the time you really start thinking "Now Im on top of it!"
At least its not a code that some shop will bang you for a grand only to have the light come back on.

So it did the same thing before the rebuild just not up until this last drive? Is your connection to your HEI? condition of plug wires, sometimes one thats arcing a bit or a bad plug can drive you nuts.
Does it do it in N or with no load on it, at steady cruise or under load?

Last edited by cv67; 11-19-2016 at 09:37 PM.
Old 11-20-2016, 08:27 AM
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Cavu2u
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Jerry,

Is it a rhythmic surging, or a random, cut-out type?
All RPMs, or just at a low, medium, or high range?

Steve
Old 11-20-2016, 08:42 AM
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shenango
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Originally Posted by cuisinartvette
woulda p'd me off about the time you really start thinking "Now Im on top of it!"
At least its not a code that some shop will bang you for a grand only to have the light come back on.

So it did the same thing before the rebuild just not up until this last drive? Is your connection to your HEI? condition of plug wires, sometimes one thats arcing a bit or a bad plug can drive you nuts.
Does it do it in N or with no load on it, at steady cruise or under load?
Before the Qjet and distributor mods it was just a mild "trailer hitching at a steady 1500 rpm while going through town. This event was really surprising and a lot worse. Even after the 15 minute drive home it was worse than anything this summer. At cruise and under load it is still very strong and there is no evidence of surge. After I got my carb back form rebuild there was still a slight surge so I dropped 2 sizes on my primary rods from 46k to 44k and opened up the aneroid setting 1 1/2 turns and the surging got better and after I put a new performance distributor in it it purred like a new Cadillac. My L48 is no fire breathing monster but it does have some decent mods to give me nearly 300 hp according to the builder. My temp stayed at 190* all day and the car was driving like a dream for the whole 3 hour tour. After the snow stops and I get back out to the garage I will check all plug connections and HEI wiring but when the ground turns white here it usually stays until April so another drive is probably out.
Jerry

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