Well after replacing the timing set i put the motor together using the 307 water pump, the 307 crank pulley and the 350's stock harmonic balancer i noticed the pulleys dont line up properly. Do i have to use the harmonic balancer from the 307 with this swap?

 

I'm pretty sure the 307 and the 350 balancers are the same. I know that if you bought a brand new one, it's going to say 68-90 Olds 260,307,350, 403 on the box

 

Thats what i thought too that their all the same. I took some measurements and on the 307 the harmonic balancer sits in an 1/8th of an inch more (2 3/8 from the timing cover) then the 350's balancer (2 1/2 from the timing cover). I'm pretty sure the balancer is in all the way as i pounded it in using a block of wood and a big hammer then used the bolt to pull the balancer all the way in and torqued the bolt to 150 and i was gonna pull the balancer off the 307 and use that but that bolt wont come loose no matter how big of a breaker bar i use, gonna borrow my friends impact gun later and try that. What am i doing wrong here why wont the pulleys line up?

 

I'm pretty sure you have to use ALL [pullley, balancer, water pump, and brackets] of one or the other to get proper alignment.
I believe Joe answered this a few times.

 

The 307 y balancer is way smaller.

If you are still using the 307 pulleys, you should use the 307 balancer too.

 

Thanks rickman and J just the answer i was looking for, now if i use the 307 balancer will that throw the crank out of balance? The reason i ask is my friends dad was telling me if i use the 307 balancer it might mess up the balancing of the crank. Thanks for the help guys time to get back to work on the motor i suppose.

 

Well i installed the 307 balancer last night installed the pulleys only to find out again its still off by an 1/8 pf an inch and the balancer is in as far as it can or will go. I'm running out of ideas. Am i missing like a spacer for the water pump pulley that pushes it out an 1/8? any ideas guys?

 

There are 3 different water pump snout lengths.
5.1" 5.6" and 6.1"

Every 307 I have ever seen uses the 6.1"

Measure from the timing cover, to the front of the pulley flange with 2 rulers, and see what your pump length is.

Also, post a pic of your pulleys and their stamped letters if you can.

The only spacers in the bracketry are used on the AC compressor, and the lower power steering pump bracket.

I'm not sure where your 1/8" measurement is from, unless one of the pulleys came from something else.

 

Will post pictures tomorrow long day, I'm eying it out to be an 1/8th inch off from the side view looking at the grooves you can clearly see its off by 1/16 to an 1/8 inch. And I had a theory. The 307 had a/c, the 350 from what I can tell was a non a/c motor could the difference cause it not to line up, but I did use all the pulleys and water pump with pulley from the 307. Even with the 307's harmonic balancer it didn't line up. Or was I supposed to use the 307 timing cover is it thinner then the 350's timing cover?