I just built a pre 80 350. Bought bare block and crank from machine shop after they done all the preliminary work on block and crank. Built it completely new pistons, rods, bearings, cam, bought used set of 882 heads 202/160 valves also rebuilt. Got it all together pulled 305 out and dropped it in my 83 Z28. Motor fired up only ran about 15 sec. and I had to shut it down oil sending unit wasnt tight. Fixed that had someone crank it and I noticed crank pulley was wobbling. Thought maybe I screwed up my balancer and that was causing it. Had problems getting it on and when tried to pull it off during build thought I might have seperated it...anyway so I got another one...installed it and it still wobbles. Its like the crank is bent or something. Could there be something major like that and it still run? And how do I figure out what the problem is? Please help, I have $2000 wrapped up in this and dont want to do any more damage than may already be.
Thanks
Bo

 

my guess is the cranks fine and either you screwed up or a part is bent.

 

How could you have separated the dampener while removing it?? Are you using the proper tools to remove/install it?? Try using the proper install tool (I made one by fully threading a 7/16" fine thread bolt the rest of the way, the bolt is about 8 inches long, and using a nice flanged fine thread nut and a big washer. Thread the bolt all the way into the crank, and then hold it still while using the nut to push the balancer on)... Don't use the crank bolt or you're asking for trouble.. Make sure the balancer is seated all the way (it seats onto the timing gear on the crank)... Is your pulley bent??

 

Thirdgen...This is my first complete build on my own and to answer your question with the first dampner no I didn't use correct tools. I wasnt aware that the dampner was actually 2 pieces and I used jaw puller instead of balancer puller to take it off cause I didnt think it was seated all the way....turns out it was seated. New dampner...yes I used installer tool and it seems to be seated all the way, but I have major wobble looks like a bent rim or something.

 

If the crank snout was bent, you'd probably be leaking oil from lower timing cover seal like crazy.

If it's not leaking, that means the crank snout is running true in the lower seal, and the problem is with the balancer. And if you don't have it, get the right size puller to take the balancer off. You DON'T want to screw up the balancer bolt hole or scar up the crank snout.

 

If you've still got it together, you might try getting it up on stands, and getting under it and firing it up... See if the pulley is what is wobbling, or whether it is the balancer... You should be able to see it under the car (whereas you might only be able to see the pulley from above)...

 

Your first guess might be the right one if the balancer itself is wobbling (not just the crank pulley- they are easily bent). It's entirely possible the machine shop machined a bent crank. Yes, it can happen. I certainly hope for your sake it's not the case, but if 2 different balancers are wobbling there's not much else it can be. It's damned near impossible to install the balancer cocked or wobbly, unless it's not on all the way (which I beleive yours is by your description).

 

Pull the pulley and check the end of the crank with a dial indicator while cranking the engine over SLOWLY, should be .002 max runout, don't have a indicator? You can buy one and a base pretty cheap these days, 20 or 30 bucks.

 

Thanks for the replys...I pulled the pulley...still wobbled, pulled the balancer...still wobled. Took a video to the machine shop showing all the above and he couldnt believe it, but totally agreed that he feels the crank is **** too. He's making it right will have a new crank kit monday, but still alot of work for me. Pulled the motor back out today and will drop pan and pull crank tomorrow. Cant believe the luck that I have. Guess it'll give me something to do for the cold spell coming...thank god for ventless propane heater in garage. Thanks again for those responding. Will keep you up to date.