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1969 miss- help!!

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Old Jun 13, 2007 | 01:27 PM
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Default 1969 miss- help!!

I have a 69 vette with a 350. When it runs it has a feeling of a miss. They motor vibrates and the acceleration is not too good. It happens throughout the entire RPM range. It happens cold and hot. I have changed everything: plugs, wires, distributer cap, rotor, points, coil, set the dwell, set the timing, cleaned out the carburator, and still it does not run correctly. It starts OK and idles but there is that annoying feeling its not on all cylinders. It does not smoke or burn oil. It runs at a normal temperature. Any ideas would be appreciated, I've almost given up! Thanks!!
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Old Jun 13, 2007 | 02:10 PM
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Originally Posted by US300hp
I have a 69 vette with a 350. When it runs it has a feeling of a miss. They motor vibrates and the acceleration is not too good. It happens throughout the entire RPM range. It happens cold and hot. I have changed everything: plugs, wires, distributer cap, rotor, points, coil, set the dwell, set the timing, cleaned out the carburator, and still it does not run correctly. It starts OK and idles but there is that annoying feeling its not on all cylinders. It does not smoke or burn oil. It runs at a normal temperature. Any ideas would be appreciated, I've almost given up! Thanks!!
When was the last time the valves were adjusted?
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Old Jun 13, 2007 | 02:59 PM
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Default 1969 miss

Originally Posted by pws69
When was the last time the valves were adjusted?
I don't know. I only got the car about 3 months ago. It seems odd that hydraulic lifters would need much adjusting.
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Old Jun 13, 2007 | 03:06 PM
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Originally Posted by US300hp
I don't know. I only got the car about 3 months ago. It seems odd that hydraulic lifters would need much adjusting.
You'd be surprised. Listen for tapping.
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Old Jun 13, 2007 | 03:14 PM
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Originally Posted by GD70
You'd be surprised. Listen for tapping.
I don't think I heard any but I will check it out. Thanks for your input. Any other ideas if that is not the problem?
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Old Jun 13, 2007 | 03:24 PM
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Did the car run fine after you made the changes to the plugs / wires, etc. or was it always happening?

Dino
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Old Jun 13, 2007 | 03:54 PM
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Originally Posted by 1stC3Vette
Did the car run fine after you made the changes to the plugs / wires, etc. or was it always happening?

Dino
It was always happening. Thats whats bugging me.
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Old Jun 13, 2007 | 04:08 PM
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look for things that are out of balance.....start with the fan clutch....is it wobbling? are all the belts running straight?

and be sure to check the firing order....these cars run amazing well even if two wires are crossed
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Old Jun 13, 2007 | 04:13 PM
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Not the first thing to check, but something to consider. The gear that went on the camshaft had a fiber coating to reduce noise. It will get worn out and put slack in the timing chain. Good luck.
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Old Jun 13, 2007 | 04:16 PM
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I would recommend you do a compression test on each cylinder. This way, you can determine if everything is ok in the valve train / piston ring area.

Good luck,
Dino
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Old Jun 13, 2007 | 04:51 PM
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This happened to me a long time ago. With me a push rod had wore a hole thru one of the rockers, making that cylander useless. The symptom was the same as yours.
missing all thru the rpm range, but at idle it was not real noticeable.
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Old Jun 14, 2007 | 08:28 AM
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Originally Posted by US300hp
I don't know. I only got the car about 3 months ago. It seems odd that hydraulic lifters would need much adjusting.
You are correct, they typically don't once they are set up. I am suggesting that they may not have been adjusted correctly. What you describe sounds like you may have one adjusted too tight. You should go through them all using the [running] procedure that is being discussed currently in the Tech section.
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