alright guys need some help here. went to the dyno a month ago and besides having tons of exhaust leaks and a fuel pump that was too small the car ran fine. drove it home and still no issues. park the car in the garage and pulled the turbo kit off to fix the leaks. changed the plugs, all gapped to .032 while it was all apart we did a leak down test, all 8 cylinders were good and even. put it all back together, replaced all of the old cracked vacuum lines, start it up and it idles fine. take it for a drive and any time im on the gas there is a vibration. let off the gas the vibration is gone......WTF happened?

just to recap:
plugs are new and i always run a .032 gap for 15psi
no vac leaks, checked numerous times
leak down test is good
the balancer is a pro products (dont think you can spin those) but it doesnt wabble
timing was at 10* base, bumped to 12, did nothing
all 8 fuel injectors are plugged in (only had to make that mistake once)

the car has lost no power, still very torquey and responsive. other then adjusting roller rockers after the leak down test, nothing mechanical has changed in anyway.

what obvious thing am i missing?

 

is any of your piping super close to the frame or the your k member? i could see the motor tilting from force and then the piping vibrating against the car causing you to feel it?

 

now that you mention it, its a possiblity. the driver side header kept blowing gaskets out because it was badly warped. it took 2 hours and a blow torch to heat the headers and keep them glowing while they were bent back into shape. afterwards the turbo wouldnt fit. had to move some stuff...............long story short ill look into that tomorrow, i get off work too late tonight to do anything

i do however already have one of those torque links. so even before the vibration i had a solid link from motor to frame and it was fine

 

oh ok i was gonna suggest u get a link after if that was what it was

 

Trans contacting tunnel? Did mounts get replaced or anything moved? Checked u joints and pinion gear and output shaft? A bad joint or bearing could do that. I've had loose joints and bearings before that only vibrated under power or hard decel. Did you pull all the plugs and look at them to see if it's something in a cylinder?

Also don't assume that it's related to recent work. Sometimes things happen that are coincidental to other stuff that's occurred.

 

Is the vibration at lower or higher speeds. My brothers 86 notch had a nasty vibration that was noticeable around 40-45 mph and got worse the faster he went. everything was tight and in working order. Pulled his driveshaft and the yolk was planed down on one side. So we swapped in my driveshaft to see if that would fix it and odd enough it didt't. It only suppressed the vibration. Now he has an aluminum driveshaft and there is absolutely no vibration at any speeds. So I'd check your yolk and U-joints as well as everything else mentioned on here already. Hope you get it solved, It's a real bummer.

 

Everyone has a vibration story to tell lol. I would go with the something is too close idea. Also, not saying something did happen but maybe something bent slightly when you raced it but didn't do much until it had time to cool down and now it wants to come say hello lol. There are a ton of things that can cause vibrations unfortunately