LT1-LT4 Modifications 1993-97 Gen II Small Block V8

383 horrible vibration above 1500RPM and throwing belts

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Old 10-31-2010, 10:01 AM
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Default 383 horrible vibration above 1500RPM and throwing belts

Well This car that i got for a good deal is starting to become a pain in my ***.

Above 1500 rpm or so there is a horrible vibration and it is throwing belts. I found the crank hub loose the other day and torqued it down took it up the street real quick and noticed the vibration.

This is what i know about the car. 383 stroker, built t56, stock rear and suspension. That is about it. I was told there is about 5k on it since built and after removing the valve cover the inside of the head looks new.

Anyone recommend a good balancer? I am debating pulling the motor out and having everything checked etc. But i hate to do that if it is something easy.
Old 10-31-2010, 10:13 AM
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check your motor mounts and trans mounts they could bring a bad vibration as well, bolt will back out
Old 10-31-2010, 10:27 AM
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Most of the aftermarket balancers are underdrive, so you're better off getting one from GM. Here's a bunch of them at Pace Performance.

http://paceperformance.com/i-5130581...-balancer.html
Old 10-31-2010, 10:41 AM
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Also if the crank was internally balanced you need to make sure that there is a internally balanced flywheel. Running a stock flywheel will cause horrible vibrations. Dont know if this is your problem, but its def something to ask the previous owner/builder about.
Old 10-31-2010, 10:54 AM
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No clue who the builder was.

Mounts are all poly and look good.

All mount bolts tight.

I know there is a zoom clutch and it looked like the flywheel was new.

The balancer also looks old and out of place on this engine.
Old 10-31-2010, 11:15 AM
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also throwout bearing could cause it as well but usually it happens around 3000 rpms to 4000 rpms so could be your balancer as well... just some things to look at
Old 10-31-2010, 11:29 AM
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Thanks.

It's been 4 years since i last worked on my old LT1 car (383 too) and I remember nothing.
Old 10-31-2010, 11:58 AM
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If your serious about getting a good one go with ATI, I had a fluidampre tear up my timing gear. The ATI is really well built and I haven't had any problems with it.

Edit:You can also throw a MSD trigger on the front of it if you want to ditch the stock computer.

Last edited by noice; 10-31-2010 at 03:32 PM.
Old 10-31-2010, 12:05 PM
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That looks like the way i will go. I am trying to find some info on a new cam and things. I would like to go 10's NA and push it to low 10's or high 9's on the bottle.



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