I have edelbrock performer heads with a around 643 lift cam. I need to put new valve springs in it. I shift at 5600 rpm, goes over the line around 6200 rpm. What springs should I use?

I think you need more information on the cam to make a recommendation. Did you contact the cam manuf and get their recommendation? Is it solid flat tapper, hyd roller, solid roller? Just fyi, i run a 512 bb stroker with a comp solid flat tappet with .648” lift and 262 @ .050” and i run isky 8005a springs. Pulls hard and fine up to 7000 on my setup. Good spring in my book.

It is a solid flat tappet, Scot Brown custom cut. Will call Scot tomorrow. Thanks.

I can't get a hold of Scott. Does anybody know what springs will fit these heads, not sure of spring pressure but it is a custom ground solid flat tappet cam with 643 lift.

You can look at those Isky 8005A springs. I have them on Edelbrock rpm heads for the last 8 years. Like i said, Comp solid flat tappet cam with .648” lift at 260’s @.050 on 110 lsa. Still working awesome. I have a new set waiting to slip in when the time comes. I’ll pull them off, test, and replace if necessary.

Yes these should work well. Look at Comp Cam 741-16 retainer and 611-16 locks for 10 degree upgrade if you do not have that already.
Todd