Standard Transmission - Bucking ?
June 4th, 2012, 05:42 AM
#1
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Standard Transmission - Bucking ?
Hey Guys,
If you read my other Thread, I got my 66 Cutlass back on the road over the weekend. Its been a while since I have had a car with a 4 speed so I wanted to ask the experts.
When I go up thhru the gears, the car pulls fine and shifts smooth. When I get to 4th (sometimes 3rd) and leave it, between 40-50 mph, the car "bucks." As soon as I give it more gas it smooths out. And when I put in the clutch, the engine idles fine.
I am pretty sure its just the gear ratio and the fact that Automatics have a torque converter to smooth that out.
I think I am over-reacting to it but I figured I'd put it out there.
Thoughts ?
GUY
If you read my other Thread, I got my 66 Cutlass back on the road over the weekend. Its been a while since I have had a car with a 4 speed so I wanted to ask the experts.
When I go up thhru the gears, the car pulls fine and shifts smooth. When I get to 4th (sometimes 3rd) and leave it, between 40-50 mph, the car "bucks." As soon as I give it more gas it smooths out. And when I put in the clutch, the engine idles fine.
I am pretty sure its just the gear ratio and the fact that Automatics have a torque converter to smooth that out.
I think I am over-reacting to it but I figured I'd put it out there.
Thoughts ?
GUY
June 4th, 2012, 06:01 AM
#2
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Join Date: Feb 2008
Location: Plano, TX
Posts: 11,798
If you have highway gears, the engine could be lugging. Do you know what your RPMs are when that happens?
Also make sure the engine is tuned correctly. If it is running a little too rich or too lean, it may lug under load but still idle fine. My Ford did that a while back when the choke pulloff was adjusted too rich.
Also make sure the engine is tuned correctly. If it is running a little too rich or too lean, it may lug under load but still idle fine. My Ford did that a while back when the choke pulloff was adjusted too rich.
June 4th, 2012, 09:33 AM
#4
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Location: Northern VA
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June 4th, 2012, 05:12 PM
#6
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Location: St Louis, MO
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What are the engine specs, cam, CR, what rpm does it buck? What carb, ignition timing (initial, total).
Most likely a carb or ignition problem if you dont have a cam with a lot of overlap. You should be able to pull from 600 rpm up at full throttle with a mild street cam.
Most likely a carb or ignition problem if you dont have a cam with a lot of overlap. You should be able to pull from 600 rpm up at full throttle with a mild street cam.
June 4th, 2012, 06:56 PM
#8
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Thanks Guys for the responses.
The car is a 330 4 bbl with an Edelbrock Carb and Intake. Pretty sure the Intake is stock or very mild. M20 is stock. Rear is a a posi - 3.23.
I'm gonna check timing and carb adjustments for sure.
GG
The car is a 330 4 bbl with an Edelbrock Carb and Intake. Pretty sure the Intake is stock or very mild. M20 is stock. Rear is a a posi - 3.23.
I'm gonna check timing and carb adjustments for sure.
GG
June 10th, 2012, 02:03 PM
#9
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Posts: 110
OK, So I adjusted the carb a little, advanced the timing to the proper 7.5 degrees @ TDC. Also found out the coil was hooked up backwards from the previous owner.
Its still bucks when I get off the gas, in very gear. I'm fumphered.
Any other advice ?
GG
Its still bucks when I get off the gas, in very gear. I'm fumphered.
Any other advice ?
GG
June 10th, 2012, 02:52 PM
#10
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Join Date: Jan 2009
Location: maryland
Posts: 1,393
I've had plug wires that made the car feel like the trans. was acting up. Make sure your wires are seperated and not touching each other or anything metal that could ground them. Open the hood at night and start the engine and look for any arching. The advice given by the others before me is all good, so if one of their suugestions fixes it.....GREAT. If not, check you wires and possibly even your distributor cap could have an "ever-so-small" hairline crack. I seem to think (like Joe P.) it is ignition related.
June 13th, 2012, 05:33 AM
#12
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Location: St Louis, MO
Posts: 904
First, you should make sure both your mechanical and vacuum advance are working ok.
If that's ok, go to the carb. May be time for a rebuild. You said it was an edelbrock, did it ever run correctly with the aftermarket car?
When you get on the gas the vacuum drops, decreasing your ignition advance, and adding fuel through the power circuit and accelerator pump.
At cruise it's running the max advancve and in the leanest condition, off primary main jets.
It could have to mave way too much advance or running too lean on the primaries.
If that's ok, go to the carb. May be time for a rebuild. You said it was an edelbrock, did it ever run correctly with the aftermarket car?
When you get on the gas the vacuum drops, decreasing your ignition advance, and adding fuel through the power circuit and accelerator pump.
At cruise it's running the max advancve and in the leanest condition, off primary main jets.
It could have to mave way too much advance or running too lean on the primaries.
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