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horrible vibrations as you rev the car and no vibrations at idle

G

GT350

Member
ok i got sent a 66 coupe to me last week,i managed to get it started idles fine when you rev it it vibrates real bad.Things i found not right on car
1. polyurethane motor and trans mounts.
2.washers in between the bellhousing and motor as well as motor plate.
3.starter has a few washesr in between the bellhousing and starter bolts taking the starter away from bellhousing it does not sit flush.
what kind of hillybilly would build a car like this.
could all of these cause my massive vibration problem.
motor is supposed to be rebuilt which it is lots of edelbrock goodies on it including new damper
any thoughts
 
Since the vibrations are not there at idle, have the drive shaft balanced. Put the rear housing on jack stands and run up to speed. Have someone behind the car looking at the tires to make sure you do not have a bent axle or wheels. Then go after the engine.
 
"janschutz" said:
The vibrations are usually there at idle, you just do not notice them. Fix the obvious things. If still there, have the drive shaft balanced. Put the rear housing on jack stands and run up to speed. Have someone be looking at the tire to make sure you do not have a bent axle. Then go after the engine.
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the vibrations are without taking the car for a drive idles fine its just when you rev it,it shakes your teeth
 
As you rev the engine, does it shake immediately off idle or does it come on slowly as you increase revs? Does it get worse as the revs get higher? What happens when you blip the throttle (real hard)?
 
"silverblueBP" said:
As you rev the engine, does it shake immediately off idle or does it come on slowly as you increase revs? Does it get worse as the revs get higher? What happens when you blip the throttle (real hard)?
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just about immediately, when i blip the throttle no vibrations and when i rev it higher it gets worse,also looked at the way the alt is mounted its got some fancy billett brackets which the alt is bolted onto but its not bolted onto the cyl head as they normally are,also looked the the engine mounts they are not even bolted onto the frame just sitting on there.
 
If the motor mounts aren't bolted down, I'd guess that's the problem. How does that even work?? The tranny holding it in place?
 
"silverblueBP" said:
If the motor mounts aren't bolted down, I'd guess that's the problem. How does that even work?? The tranny holding it in place?
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the mounts are bolted onto the motor but just sitting on the frame mounts on both sides the 2 long bolts/nuts are missing
 
Sounds like you better be going through this car with a fine tooth comb to figure out what all is screwed up. If they don't have the motor mounts bolted down, I wouldn't dare start the car up again until I've gone through the entire thing. There shouldn't be any kind of washers between the bellhousing and motor. Is this an auto or manual?
 
"buening" said:
Sounds like you better be going through this car with a fine tooth comb to figure out what all is screwed up. If they don't have the motor mounts bolted down, I wouldn't dare start the car up again until I've gone through the entire thing. There shouldn't be any kind of washers between the bellhousing and motor. Is this an auto or manual?
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its an auto looks like a someone high on crack put it all together i will be going thru the whole engine bay someone threw a lot $$$ on the motor all new stuff see pic,to make things worse its a power steering car the the idiot bolts on a single groove crank pulley

322.jpg
 
"TB350" said:
Correct imbalance on that new damper? kip
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I agree...either that or incorrect flywheel.



BTW that looks like the work of a coke-head. A crackhead would have reinstalled the PS pump (and looped a coathanger around the brake cylinder and clamped it on with vise grips).
 
update

changed the motor mounts back to standard rubber ones.
the sump was sitting on the crossmember (aftermarket chrome) easy fix.
next issue was the power cylinder was right up against one of the header tubes the previous owner never bothered to use a power steering drop mount so i will ammend that.
There is still a vibration but not as bad as it was at first once i have sorted the steering ram i will look into the damper/flexplate.
 
Check the spark plug wires to make sure the firing order is correct, two wires crossed will allow it to idle but it'll rev & vibrate badly.
 
another update

dropped the starter to check block i.d turns out is a 87 302 block e7te
when i took the starter off i noticed someone had cutaway part of the engine plate where the starter index's itself.
The flexplate had 50oz written on it.
The front damper id. C80E 6218-A3
I think i have found my problems.
 
That would really make me wonder what the internals are balanced as? I'd guess 50 oz, and they used the original balancer to use with the original crank pulley and v-belts.
 
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