04-20-2019, 04:55 PM | #1 |
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Location: Buford, GA
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Stumble
Probably a dumb question for most.
But what would cause my stock Holly 50 Merc to stumble shifting between gears? Almost a jerk Thanks Rand |
04-20-2019, 05:57 PM | #2 |
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Re: Stumble
Vacuum leak ?
Bruce
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04-20-2019, 06:18 PM | #3 |
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Re: Stumble
If overdrive equipped there is a momentary engine kill to aid in shifting.
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04-20-2019, 10:12 PM | #4 |
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Re: Stumble
Cmbrucew wouldn't a vaccum leak be noticeable at idle as well?
I'm going to spray some starting fluid around and see what happens 34pkup are you referring to the kick down switch that takes it out of OD while passing? Thanks for the ideas...anymore? |
04-20-2019, 10:51 PM | #5 |
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Re: Stumble
Loose motor mounts.
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04-28-2019, 01:02 AM | #6 |
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Re: Stumble
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Could be electrical also. Do you have a 3 on the tree OD? Last edited by Tinker; 04-28-2019 at 01:23 AM. |
05-02-2019, 09:56 PM | #7 |
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Re: Stumble
Tinker..yes 3 on the tree with OD
But all OD electricals disconnected Its a stumble between gears. If I ride the clutch it does not do it. Im thinking it's something in the Holly carb? IDK? Daytona parts in Fl. Rebuilt it in 2015 Not many miles on it since then. Finally getting back on the road after being parked for 2.5 years due to messed up steering column and shift linkage. But always ran it regularly to just hear and gun the flathead. I think it's in the carb? Maybe Motor mounts are good. Sprayed starter fluid all over intake with no change? Ideas Im missing? Last edited by Rand; 05-02-2019 at 10:01 PM. |
05-02-2019, 10:05 PM | #8 |
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Re: Stumble
So if you keep the rpms up it won't stumble when shifting?
But going from higher rpms in a lower gear, to a higher gear it bucks till it reacts a decent rpm, then runs well. Not sure it's fuel, but could be. What carb? if I missed it. Shifting to a Higher gear would lower engine vacuum a bunch at shift point reducing fuel flow and engine vac flow. Which the pv should kick in. just a guess... could be a lot of different things too. Maybe a bad condenser. But I agree on the carburetor. Engine,carb,valves, and condensor issues don't show themself idled parked in a garage. Last edited by Tinker; 05-03-2019 at 12:27 AM. |
05-03-2019, 12:34 AM | #9 |
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Re: Stumble
You let off the gas when you push the clutch in to shift, then throttle up as the clutch comes out. If the accelerator pump was not working it might cause a stumble as the throttle opens with no accelerator pump squirt.
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05-03-2019, 10:42 AM | #10 |
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Re: Stumble
Check the OD cutout switch under the accelerator pedal.
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