Going nuts... help
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Joined: Aug 2008
Posts: 80
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From: Saskatoon Sask.
Going nuts... help
Here is my problem.. I have a 1978 coupe which I drove for a short bit before shutting it down (with no problems like this) and changing the motor to a gm crate motor (350 cid 330hp version) keeping the same tranny (t350)with the only mods being a B&M shift kit as well as a 3500stall convertor. Motor runs perfect, smooth yet you can hear a bit of a cam. When driving and picking up speed at a normal rate it hits second gear and seem to have a real good vibration, as if a tire is way way out of balance (not the case). The only time you really feel it is at the low end of second gear as well as the low end of third when giving it a tad more gas. Seems very strong and have not noticed the vibration/shaking when I step on it fairly hard. Is it possible that the torque convertor can do this? Its driving me crazy.... HELP!
thanks
Rob
thanks
Rob
Racer
Joined: Jun 2008
Posts: 269
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I've had stall converters before and they didn't vibrate. I recommend you start checking for loose fasteners. Try the torque converter to flex plate bolts first. I've seen these come loose before. Did you use Loctite?
If those bolts are good, there may be a U-joint going bad somewhere. It's not uncommon for other stuff to start to fail when the horse power is suddenly increased.
Such is the work of hot-roddin...
Good luck, I hope you find the issue.
If those bolts are good, there may be a U-joint going bad somewhere. It's not uncommon for other stuff to start to fail when the horse power is suddenly increased.
Such is the work of hot-roddin...
Good luck, I hope you find the issue.
Thread Starter
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Joined: Aug 2008
Posts: 80
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From: Saskatoon Sask.
Loctite
Yes.. I used loctite on the flex plate.... just came back from another ride.... you know... when it is vibrating I do think hear a dif in the engine. I had put on 1.6 rockers on which I think I failed to mention before, long slot which I do remember being kinda sloppy. 1/4 turn after lash is what I gave it. This week I am going to put the 1.5's back on... worth a shot. I went through everything that could be loose and nope. I did also pick up the drive shaft u-joints as you had pointed out...this car is not used too the extra hp, how true. Do you think my rocker thing may be it??
thanks
Rob
thanks
Rob
Drifting
Joined: Jul 2003
Posts: 1,253
Likes: 1
From: East China MI
I do not think it is the rockers. They would just make noise but not vibrate.
It has to be part of the rotating assembly.
Check everything that has been changed.
The harmonic balancer?
Trans mount?
Drive shaft weights?
If you can duplicate the vibration with the car staionary, I would suggest using a stethoscope. You can a cheap one at any auto parts store. If not, have someone ride with you, remove your shift boot, and put it on the top of the trans or the shift mechanism. I'm suspecting that if the only change you did to the trans is the converter, you may have uncovered a weakness in the trans.
Good luck.
It has to be part of the rotating assembly.
Check everything that has been changed.
The harmonic balancer?
Trans mount?
Drive shaft weights?
If you can duplicate the vibration with the car staionary, I would suggest using a stethoscope. You can a cheap one at any auto parts store. If not, have someone ride with you, remove your shift boot, and put it on the top of the trans or the shift mechanism. I'm suspecting that if the only change you did to the trans is the converter, you may have uncovered a weakness in the trans.
Good luck.
Racer
Joined: Dec 2007
Posts: 445
Likes: 2
From: Thomastown Mississippi
I know this is a long shot but you might check and make sure your water pump bearings are not going bad. My 77 developed a vibration and I drove it for two weeks trying to figure out where it was coming from. Finally noticed coolant being slung on the underside of the hood. Reached down and rocked the fan back and forth and sure enough, 1/4 inch of play. Replaced the water pump and the vibration went away. Just something to check.
KC
KC
Melting Slicks
Joined: Mar 2008
Posts: 2,336
Likes: 1
From: North Bellmore Ny
St. Jude Donor '09
I do not think it is the rockers. They would just make noise but not vibrate.
It has to be part of the rotating assembly.
Check everything that has been changed.
The harmonic balancer?
Trans mount?
Drive shaft weights?
If you can duplicate the vibration with the car staionary, I would suggest using a stethoscope. You can a cheap one at any auto parts store. If not, have someone ride with you, remove your shift boot, and put it on the top of the trans or the shift mechanism. I'm suspecting that if the only change you did to the trans is the converter, you may have uncovered a weakness in the trans.
Good luck.
It has to be part of the rotating assembly.
Check everything that has been changed.
The harmonic balancer?
Trans mount?
Drive shaft weights?
If you can duplicate the vibration with the car staionary, I would suggest using a stethoscope. You can a cheap one at any auto parts store. If not, have someone ride with you, remove your shift boot, and put it on the top of the trans or the shift mechanism. I'm suspecting that if the only change you did to the trans is the converter, you may have uncovered a weakness in the trans.
Good luck.
With the balancer, try a tci the rattler and you will never regret it
Thread Starter
Advanced
Joined: Aug 2008
Posts: 80
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From: Saskatoon Sask.
Update
Ok... changed the rocker back to the 1.5's w/1/4 turn... yup, you are all right.. not the problem. Verified timing.. total 34 degrees all in by 2600. Not the problem.
Lifted the rear tonight off the ground and took it for a ride without going anywhere.... smooth as silk shifting and rpm. But... as it was in gear and I was under the hood hit a major dead/stumble spot in the carb. A little more throttle and I can see gas pretty much dripping down. Then the rpms pick up. Took it up to @ 60mph without a vibration. I tryed slowly throttling up under hood again and same thing, major stumbling spot... could this do it??? The carb is rebuilt/remanufactered (Summit) q-jet 750.
thanks all
Rob
Lifted the rear tonight off the ground and took it for a ride without going anywhere.... smooth as silk shifting and rpm. But... as it was in gear and I was under the hood hit a major dead/stumble spot in the carb. A little more throttle and I can see gas pretty much dripping down. Then the rpms pick up. Took it up to @ 60mph without a vibration. I tryed slowly throttling up under hood again and same thing, major stumbling spot... could this do it??? The carb is rebuilt/remanufactered (Summit) q-jet 750.
thanks all
Rob
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Thread Starter
Advanced
Joined: Aug 2008
Posts: 80
Likes: 0
From: Saskatoon Sask.
Update 2
Well.... changed carbs yesterday to a edelbrock performer 750, got rid of the stumbling but still have the bloody shake/vibration at the low end of 2nd and third. Warmed it up good today with a good ride and also see that I have too much tranny fluid in there... about an inch above where is says hot in park on the dip stick, unsure how that happened. Going to drain some and see if this does it. If not... I am going to change out the torque convertor... just too bad I didn't keep the old one. This trial and error checking is costing major coin.
Rob
Rob