Holley/Demon Carb stumble

Ok, had to go look and see for myself. The only difference I can see between the ProForm blocks is the standard calibration block has the port for timed vacuum advance and three emulsion holes. There is nothing wrong with that. Make sure the 1-3 holes have a .026-.028 bleed and block the number 2 hole and go. Always check to see the size of the bleed holes in the block. I've seen some as big as .034 and PF says not so. I have the blocks to prove it. So they can bite me.

The other block doesn't have a timed vacuum port and 4 emulsion holes. Same thing as above...1-3 get .026-.028 bleeds and 2-4 get blocked.

As to the idle feed restriction, PF has them in the high position in the block. I've spent more time screwing around lowering mine and my engine HATES the lower IFR position. Drives all the carb gurus nuts because they say the science is settled. So that would be one more thing to tune. If you can't clean the idle up, lower the IFR's. You probably have to tap the lower holes but that's easy.

Either of those blocks will work.