Hey all I dont post much here mostly read up what everyone's doing to their SBC and yes Pontiacs to get ideas. I now have ask question. Son and I did a eng swap in his 89 Bird 350 to a 400 (406) we took off all the serpentine stuff from the 350 and put on the 400 (its a 78 block) no smog pump crap though lol and AC delete bypass pulley. We did have a little sequel noise with belt but went little smaller belt 968 to 960 and it went away. But now its throwing the belt off. Read up could be a pulley off alignment only one we can see is the crank shaft pulley just tad forward what can we do to fix this. Or anyone else on here do a swap like this. Son bird runs really strong with the 406 now just darn belt and sure in time will need rear end and trans LOL. Thanks Tim

 

definitely sounds like it needs to be properly lined up. shimming the brackets that the PS pump or whatever component is not in-line using washers would do it.

 

Serpentine setup shouldn't have any problems throwing belts. That's pretty much exclusively a V-belt thing. Use the right length belt, if the indicator on the tensioner is in the right 'zone' it should be good to go. Shouldn't need to shim anything, or align anything, it's pretty much the closest thing yet to plug and play.

 

yes, drew is right. I must have glossed over where you mentioned serp. belt setup. I was thinking of my V belt setup. he is correct

 

If the crank pulley isnt aligned with the rest of pulleys you may have to do some machining to make it work. Check alignment but I wonder if dampener is fully seated on crank? Also 400 are externally balanced so are the dampeners a little different than the rest? May have to compare the 2 dampeners side by side to see if different heights. Take the time to figure it out and one awesome engine combo!

 

And 1 more thing to add:
Uness the harmonic damper is not fully seated, which means the crank gear of the timing set should be fully sandwiched in between.
On my 334, I had to machine some material from the back of the crank gear to get the timing chain alignment correct. Hardly anyone ever checks for this.
If your timing set gears are in alignment, then you could have a little machined from the hub of the damper (not the pulley side) so that the front face will be further towards the block. This assumes that the rest of the pulleys actually are in alignment with each other. A straight edge is your friend here.