Let me start by giving the engine specs. I have a 491 stroker engine. Bore: 4.290, stroke: 4.250. The compression ratio is 10.3:1. Crower mech. roller camshaft with .641/.636 lift, 256*/ 266* @ .050. Edelbrock Performer RPM 454-R aluminum heads, Victor Jr with 850 Holley carburetor. I have it running and have the timing set at 26* initial and 38* total with the MSD Pro Billet Distributor. My problem is even with the 26* initial timing I have to open the primary throttle plates too much uncovering the transfer slots. I need the idle to be around 900-1000 rpms. I have been reading on tuning Holley carbs. They suggest drilling 1/16 holes in the primary throttle plates and going up in size until I get the idle to what is needed. Does anyone have some other opinions?