Help with mystery chainsuck.
 

I just returned the 6 speed Super Record components to my '81 Medici. When I took these parts off 6 years ago, everything worked fine. Now, I have some chain suck on the bottom of the small ring. The SRAM chain (PC58?) is not worn--IF ANYTHING, IT IS TOO TIGHT? The Park chainchecker has a tight fit at 0%. The chain was stored clean, lubed and it was shiny just now when I put it on. Any suggestions?
Thanks,
Jeff

You could try a different chain, just for yucks and giggles.

Check your chainrings for tooth wear.

+1, chain suck is usually caused by a worn ring.

Good idea! Everything is fine with an old chain that shows .75 on my Chain Checker. I just got back from REI with a new SRAM PC-870 (8 Speed) and it is also tight. Why would a new chain read less than 0 on my Chain Checker? I thought that there were standards regarding chain link length. I'm returning the chain, contacting SRAM and considering another chain manufacturer.

Everything worked well before putting away. Now it chain sucks?

My guess would be thickened lubricant. I have seen oil, as well as grease, turn to an almost glue like consistency. Just a guess. Give the chain a good shot of WD40, rotate lots, flush again, then give er a go. Might work just fine, might not. Very little work/effort to find out.

If this does work, don't forget to replace the chain lube, to push out the WD40.

Did you take the rear derailleur apart and then reassemble it? If so, you may have slipped the pulley spring end into the wrong hole in the cage plate, thus reducing the pulley tension. I did this on my bike and it resulted in bad chain suck on the small chainring due to insufficient tension to pull the chain off the chainring.