These videos will help you a lot.
http://www.youtube.com/watch?v=3ixfD...eature=related
http://www.youtube.com/watch?v=YdIGZ...eature=related

 

So when i got home me and my son pulled the plugs and roated the motor using the screw driver method to find tdc. its really hard to use this method, but to the best that we could tell it seems the pointer lines up with 20 btdc. is this possable? maybe i have a crank that didn't match the new balancer. was there any balancers that were 20 degrees different from others? why did my motor start before? do i install the dizzy the way i left it, at tdc i think! help!!!!!!!!!

 

There is a harmonic balancer for the 305 that is just about 20° off when you put it on a 350. I would double check your part numbers. Oh and if the 350 HB is put on a 305 you will get the same thing. It has to do with the key on the crank end of the balancer.

Massey

 

Once you've determined TDC, then just make a mark with paint, or a file on the balancer. After that you can use that mark to put a timing light on it and set the timing. When this is all done you might want to use some liquid steel and fill the old mark so it wont confuse anyone in the future.

 

There are a couple of different 6-3/4" harmonic dampers. Since your engine isn't a 400 (that uses an 8"), yours isn't a balancer, it just dampens crankshaft harmonics (vibration frequency). The early ones had the timing notch 10 degrees off from the keyway (notch would be to the left of the key slot as you're looking straight at it). Somewhere around the mid to late 70's, the timing notch was changed to line up with the key (0 degrees). It's possible that somewhere along the line someone did a mix & mis-match of damper and timing tab/chain cover with your engine. It's easy to do if you don't know what to look for. Another possibility is that your damper could be badly worn (old and dried out rubber ring) to where the outer part of the damper could spin separate from the inner hub. You'll never find your correct timing by the factory mark if that's the case. These are the reasons why I was getting you to find where your true TDC is, and mark the damper accordingly. Hopefully you did it right. And if you did, then that's the mark on the damper to follow, not the factory notch.

 

the damper is brand new from napa. the car is a 1980, but it had a rebuilt engine in it. (crate motor) where is the key way in relationship to the mark on the damper? my big question is would the motor start if it was really 20 degrees out? not sure what to do!!!

 

I suppose you must have the crank bolt in. If it's not too much of a pain, remove the bolt and see where the mark is in relation to the key. Did you have an old engine in the car, or start with an engine-less car? If you have the old, how does the damper and timing cover/tab compare to the new? And when doing the TDC test, are you absolutely sure you got it right? If you want to check it the dead-nuts way, you can get (or make) a piston stop that screws in place of the spark plug. If it doesn't want to start where it's set, rotate the distributor clockwise a tad (counterclockwise advances the timing).

 

with the timing mark on damper pointing alomost 12 oclock the key way is to the right lineing up wth the btdc timing tape on the damper at 27 +/-. wat damper is this for? the motor is a crate motor that came from S&S motors from washington. the crate motor was bought from them around 2002. does this help. thanks for all the help guys!!!!!!!!!!!

 

Where does that put your mark that you made when you checked TDC on the #1 piston?
To confuse you more, when the #1 piston is at TDC, the crank key is at the 2:00 position.
Sounds like you have a 12:00 marked damper but want a 2:00 one (lining up with the key slot). Looking at it that way, does it look like a timing mark in line with the key slot will put it in the right place in relation to the timing tab?

 

well after searching some, i decided it must be a 12 oclock damper. so i left it the way i had it with tdc using the screw driver. i pulled the old dizzy out and inserted the new dizzy and had the rotor point towards #1 as close as i could get it and lined up the #1 terminal over the rotor. i tried starting but had to advance a bit to get it to fire. it did stumble a bit though, seemed to rev okay. so i think its close and i may of been stumbling because it was cold. i did shut it off because my friend is coming over later to adjsut the valves with the motor running. my headers were getting pretty before so he thinks the valves might be causing it.