IROCmenace

iTrader: (1)

1988 IROC-Z 5.7 TPI Auto 2.77 gear
I did search

I got this car back in October. I have been rebuilding the most of it since.
All I lack is Earl's brake lines and T-top seals and the car will be mechanically sound except for....
When I bought it I could see the crank pulley wobbling, making the tensioner bounce. I replaced it with a Pro Street balancer from Summit. It made a small difference. I later bought a Motorvation Underdrive pulley set and no difference. I can feel the vibration at 2500-3000 RPM's the most. At 1500 I can barely feel it and there is a rumble at idle but it could just be the age of the car.
I have watched the flexplate turning with the engine running and I can see a slight wobble. Not as dramatic as up front.
It doesn't knock, and it seems to have the normal amount of power for the minor stuff I have done to it.
The engine probably has about 10-15K miles on it.

1. Is it possible the flexplate or torque convertor could translate the vibration to the front?
2. Am I screwed?

This is my daily and my wife is due with our son in July. I can't afford and enigine or another car. Please tell me some good news.

Sonix

iTrader: (1)

Uhh... ooh.

You might have a bent snout on your crank. I'd pull off all your accessories (except the waterpump), remove all belts, remove the balancer. Start the engine, and watch your naked crank spin. It'll puke some oil out of the timing chain cover, but watch the crank. It should be smooth as glass. Get your buddy to rev it up while you watch it.

Be prepared for bad news.

IROCmenace

iTrader: (1)

Thanks, I have a gut feeling the crank is jacked. I may just drive it till it blows.

InfernalVortex

iTrader: (4)

If it's running fine as it is, how big of a deal could it be?

The crank pulley on my 305 did that (I haven't checked to see if it followed it to the 350 yet, though) and it may well have been a bent crank snout in that case too, but I'm convinced that thing would have outlived Cher.

Saculia

iTrader: (1)

My crank on my 305 did the exact same thing when I bought it. Just like you I initially speculated that it could be a pulley or something simple as that. It actually happened to be 2 bent connecting rods. I drove the car for about 12K miles before it developed a bottom end knock.

IROCmenace

iTrader: (1)

Well I guess we will see what happens!!! At least I can save money on a new flexplate and torque convertor.

I have really started to wonder why I like these things. I am sure as much of a headache as they are I will still getting them.