I have the heads on my 502 in the machine shop and want to install new valve springs. However I want to use stock Merc retainers and valve seals. Does anyone out there have a part number for a good aftermarket spring that'll work on this set up? Or should I just order stock Merc ones? Also looking for a part numer on good roller rockers that'll work on these heads without any mods to the rocker stud? Any ideas??
Thanks,
Mike

Change your springs to comps, and use Viton seals

need more info on your heads, which 502 are they off of, and why on earth would you want to use stock merc stuff in that area when there is so much better aftermarket stuff out there.

The heads are cast iron Gen VI that have had a little port work done on the them. Stock valves.

The springs you should use are based on the cam. There is no reason to use merc anything. Just get new springs matched to the cam and the retainer kit that goes with them. Sameewith the seals. Use a good aftermarket seal.