Vibrations

[Lit549]

Hmm,well i know i boight it for a 96 vortech if i remembet correctly.Its been awhile..Im seriously thinking aboit a fluiddampner..May help? Im frustrated,maybe its just bad harmonics?

[Lit549]

are you sure the balancer was for the crank you currently have?

Ya its 86 and newer one piece main flywheel,balancer is professional products 8" balancer..Its not misfirng and i took all belts(and balancer hub) off and it still vibrates..Maybe its just bad harmonics? piece of crap balancer? When the trans was built, maybe they didnt clock flywheel right? Im frustrated!

[bd]

Vibrations can be a real nuisance, not to mention destructive.  You've mentioned an 85, 86 and 96 Vortech.  Which is it?  Does it have a stock rotating assembly?  Stock one-piece-seal SB cranks use a neutral balancer and counterweighted flexplate.  Many aftermarket forged cranks are neutral/neutral.  Do you know the build details of the motor you purchased?  Have you spoken with the builder?

The flexplate will attach to the crankshaft only one way - 'clocking' isn't an issue.  Did you unbolt the converter and slide it back away from the flexplate to isolate the motor from the rest of the powertrain?

Fluidampr is an excellent product.  Though, Streetdampr is better suited for street use and more affordable.  Still, both are pricey.  Yet, neither will solve an imbalance caused by a flexplate or converter, or that results from an unbalanced rotating assembly.  And, realistically, your not likely feeling harmonic vibration at only 2 grand. 

Look at the balancer currently on the engine.  Does it look asymmetric (more heavily weighted on one side)?  Inspect the flexplate for counterweights.  Unbolt the converter and slide it away from the flexplate.  Then talk with the engine builder. 

[Lit549]

Well its 85 c10,96 vortech 350..85 350c trans,lockup converter..Thats the only thing i havent done is slide the converter back..I helped on and off when we built it..Its all stock assembly accept a zz4 cam,with the comp beehive springs and lifters..Assembly wasnt balanced the flexplate is correct as is the balancer..At highway speeds its smooth at 70..At 45-50 its vibrating in and out,i can put it in neutral@ 45-50 and the vibration stops..I can rev it (while coasting) and when engine comes down off rev it vibrates..Or hold throttle @1300-1500 rpm(while coasting) it vibrates..Its def in engine not driveline..Feustrating as heck..thanks for the help..

[Lit549]

http://m.youtube.com/#/watch?v=9MWvuaKNUFY
Well heres a video of the flywheel. I think ive narrowed down my vibration to the flywheel..I seperated the converter and there was still the same vibration..I filmed it hooked up and unhooked...Its not the converter.  Need some opinions,would you change this flexplate? I have vibtation in neutral,it is in the engine for sure..Looks pretty bent to me? ..thanks

[VileZambonie]

No, I would fix the misfire you have. Find out which cylinder is misfiring. Use a pair of insulated pliers and one by one isolate which cylinder isn't contributing.

[Lit549]

Ya,i checked all wires for resistance=all good..Cap -rotor -coil all good..And all new plugs,it had a plug that i had just cracked the porcelin right before this and it was missing,i fixed that.I found that some of them have a little oil on threads though.Engne only has about 5k miles..Vibration is there no matter what i do..

[VileZambonie]

Make sure you don't have #5 and #7 wires crossed.

1-8-4-3-6-5-7-2

[Lit549]

#5+#7 are correct..Think im about to just change it,better safe then sorry i guess.Im sure gonna be mad if it not the source of vibration! Hahahaha

[Irish_Alley]

ok for one you have 2 different topics for the same problem throwing parts at her now you want  to throw another part at her. i cant watch the video but knowing vile from here if he says he sees a miss i would bet anything hes right. i would recheck everything before you throw anymore parts at it. oil on the threads is probably from leaky valve cover gaskets unless your electrode is some non normal color than i wouldn't worry about them but make sure they all are firing (all electrodes about the same color). one way is when the engine is cold you first start it up touch each exhaust manifold if you dont have one of those fancy laser temperature readers. but make it quick cause it will warm up fast see which one stays cooler than the rest.

[Lit549]

Well,i changed the flexplate and the vibration is still there! Changed motor mounts, still there.All thats left is the balancer and it looks fine but guess im gonna have to change it just so ill know..Gonna check exhaust for anything touching or something stupid like that..Maybe its just in the internals which isnt good,im def investing in balancing everything next time!

[VileZambonie]

correct me if im wrong but the 400 is internal balanced while the 350 is external miss matching parts will do this also

You have this backwards.

Ensure your firing on all cylinders, do a power balance test.

Isolate other componenets, make sure the exhaust isn't rubbing.

[Irish_Alley]

thanks vile knew one was different than the other but couldn't remember which one was what

[Lit549]

Well found it! I was tired of this exhaust sounding like glass packs a few mnths back and cut exhaust off behind the mufflers,well i re welded them back on today hoping that this would be it(last ditch effort)..And there ya go,no vibration..I wouldve prob noticed this if i drove it everyday at the time,but it always sat till my mx accident and now i drive it daily..Soo,guess im a idiot or sure feel like one..Ive replaced flexplate,fanclutch,motor mounts,and fixed my lean ass eddy carb..So all in all everything needed replaced anyway so i guess no harm,just a bunch of stress worrying that it was the engine..Lesson learned!! Thanks for everybodies help!!

[Engineer]

correct me if im wrong but the 400 is internal balanced while the 350 is external miss matching parts will do this also

Irish you are close..... The 400SB is external balanced, the 350 and all other small blocks are internally balanced.