motor is having some problems.... - Team Camaro Tech
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post #1 of 6 (permalink) Old Oct 16th, 01, 01:55 PM Thread Starter
Join Date: Oct 2001
Posts: 7

I recently bought a 69 camaro that has a 383 in it. i was driving it home and the whole car started shaking really bad. I checked everything out and the vibration damp. was a little wobbly so i changed that out and it is still there. @ 2500-3000 rpm in or out of gear the car is vibrating me to death!!! i took it to a local tranny shop and he said it was the flywheel or the t. converter, (he disconnected the two and ran it). what else could it be? If something was out of balance(pistons,rods, etc) would it cause a vibration like this? thanx for your help.
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post #2 of 6 (permalink) Old Oct 16th, 01, 03:47 PM
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Location: Wilton, Ca. USA
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Being that it's a 383 the first thing I'd suspect is an incorrect balancer or flexplate. Does it have the vibration in park or neutral? This would eliminate any driveline/front end/tire balance issues.

The majority of the cranks used in 383 applications require a 400 flexplate/flywheel and balancer; in other words they're externally balanced whereas a standard 350 is internally balanced. The balancer and flexplate/flywheel have an extra weight attached to them and not having the correct ones for the engine will cause a MAJOR vibration which will hurt the engine. Identify which ones you have; get help from a machine shop or auto repair facility if you need to.

You also should talk to the guy who had the car before you and see if he has any info. Maybe he knows who assembled the engine and what balance it needs?

Bottom line, get it figured out before you hurt something. Did you test drive the car before buying? Was the vibration there at that time or is it something new?

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post #3 of 6 (permalink) Old Oct 16th, 01, 09:21 PM
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It very well could be the torque convertor...although I have never had one vibrate really bad, I guess it could happen. I have had a couple of different cars start vibrating mysteriously at around 2000 rpms or so. Both eventually turned out to bad torque convertors...something broke loose inside and threw the balance off. Using a cheapie convertor behind a strong smallblock can easily do this.

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post #4 of 6 (permalink) Old Oct 17th, 01, 07:29 AM Thread Starter
Join Date: Oct 2001
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Thanx for the replies. i had the flywheel away from the t converter and the vibration was still there. That rules out everything on the car besides the motor. When i test drove it, i felt nothing. it felt good. but as i was driving home, i started to hear a humm which has turned into a vibration.
while under the car i saw that the weight was on the flexplate and i just had a 8" balancer put on yesterday, so i know its not those two. What else could it be?
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post #5 of 6 (permalink) Old Oct 17th, 01, 02:02 PM
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Location: Waldorf Md. USA
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If the car ran smoothly when you test drove it, I doubt that the problem you are having now is actually a "vibration" in the out of balance sense of the word. I am betting that the motor is just running roughly due to a carburetion, ignition or other problem. If the flywheel or damper had been wrong, or the motor not balanced correctly, it would have had the problem when you test drove it and when you first started driving it home. You say that it suddenly started doing it, thats why I am leaning towards a rough running condition. Plug wire come off ? Carb float stuck all of a sudden ? Etc Etc Etc. These are the types of things to be looking for.
By the way, when you replaced the the new one for a 400, with the cutout on the outer ring. This is what the 383 should have on it. The wrong damper will also cause a vibration, but your problem was not there when you first got the car,, so I dont think the damper was, or is the problem.
Hope this helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner
1973 Z-28 family car...Brother bought it new in 73
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post #6 of 6 (permalink) Old Oct 17th, 01, 02:48 PM
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Maybe a vacuum line has fallen off. I've had rough running vibrations before when a spark plug becomes totally fouled by leaking valve seal. Another possibility is a cam lobe flattening out. Do you have lifter noise when you start it the next morning when it is cold?
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