Hi,

Purchasing a new MSD black ready to run distributor #83873 and need a little help with a baseline for the springs. Dont know specifics of pistons from rebuild but told stock replacements. Has Edelbrock Performer heads and intake, a Holly Avenger 770, Stock HO exhaust manifolds. Current distributor set up by FBO before the new heads and carb has about 14° initial and 25° all in.. Not sure what RPM all in, maybe 2500? It is not a performance build ..Drives like a cruiser and has one cylinder a little down on compression. No other issues. I attached the spring guide. It comes stock with a blue bushing for advance stop at 21 degrees which seems right and the heavy silver springs, which is the slowest advance. I was thinking about starting at either B or C. Any ideas?

I use the two light springs and the black bushing so I get to set the initial timing between 14 and 18 degrees BTDC and make sure that I don't have any more than 36 degrees total timing revved up to full mechanical advance. I've never had a B or RB motor like any less than 32 degree total timing, never
That (34 to 36)works really good on the street and at the track