I got rid of the vibration that happened when I swapped the cam and installed a new SFI flex plate. I had installed the flexplate incorrectly indexed. There seemed to be a general consensus they can only be installed one way, NOT TRUE. Make sure you line up the middle hole (between the two "top" bolt holes) in the flexplate with the unthreaded hole in the crank. My crank did not have a locating dowel even thought it is externally balanced.

It's no fun 47 years old, arthritis in both hip joints, lying on your back on concrete, 95 degree heat, gnats and flies bothering you, car on jackstands, motor and trans still in the car, trying to figure out how you're gonna make enough space to get to the flexplate bolts, how to keep the motor from turning, trying to get enough leverage to loosen the VERY TIGHT bolts, repositioning the flexplate correctly, trying to get the bolts started in a space just big enough to get your fingers in, getting up and down from under the car 50 times to rotate the motor to tighten the bolts or get another tool, repositioning the trans to line up with the motor so you can start the bell housing bolts, etc. etc.

The bottom line is, sometimes a seemingly simple task is not so simple. Pay attention to the details and do it right the first time. I guess it's true what they say "Experience is the best teacher". I don't think I'll ever install another flexplate incorrectly! And to think I turned down an opportunity to go shopping with my wife and kids yesterday. I was done before they returned home.

 

Glad to hear you got it worked out. Hopefully I will never be in the same boat but I can see it happening. Thanks for posting your findings and the results of your fix. That is what makes this place what it is.

 

Was just thinking about you and checked my crank before I read this post and it does have a locating pin, wonder what happened to yours? Glad you got it figure out but that is a lot of extra work.

 

 

Thanks for sharing this information. My engine has had a nasty vibration ever since installing it. I've tried everything short of checking the flexplate orientation ever since. You have just turned me on to my next Vette related project...
I sure hope this does the trick.

 

Very good post nastee, I think you really told it like it is. And this does help the rest of us with similar problems. As it shows how getting it done right pays for itself. Hard work is sometimes the price to pay for owning an old corvette but I just can't throw in the towel and buy something newer. Its still a hobby and the repair efforts are really just for me anyways.
I can remember installing the clutch disk on my pick-up backwards. Having to admit defeat and call the tow truck was a bad feeling. But hey I'll still a motorhead and enjoy wrenching on the shark whenever I have the time.
Anyways it was good to hear you found/fixed the problem and can share it with us. cardo0

 

Glad you got it fixed Nastee, Thanks for the follow up post. I live in Ga and I know all about the heat. Make sure you drink plenty of cold beverages for a project that involes working on the vette.

 

This afternoon I removed the inspection cover, and unbolted the torque converter to have a look. Unfortunately, I discovered that the dowel pin is installed in my SCAT crank so apparently there is NO way that my flex plate is installed wrong. I guess the problem with my engine is just poor all around balance.

Even if removing the flex plate would have been necessary, my torque converter would not slide back far enough to work with the bolts that hold the flex plate onto the crank. I would have had to remove the transmission but it would have been worth it.

Congrats on getting your problem worked out nastee383.

 

thanks i will make sure i don;t mess mine up... i know i would have

 

Glad to be of assistance.

 

was your vibration constant at all RPMS...
how bad was it?
i have always had a slight vibretion at around 3000 RPMs...

 

It was significant. At idle the seats were visibly vibrating, the back bumper around the license plate was vibrating (aftermarket fiberglass) and driving at 2000 rpms was bad enough I wouldn't go beyond that rpm. I drove up my street and back a couple of times, about 1/2 mile total, before I decided it was bad enough to take care of ASAP.