First of all, I don't claim to be any kind of mechanic so I figure stuff out and look it up as I go, just saying that now because you're all probably going to think I'm an idiot. Ok, so my truck has a 351M/400 and I recently ordered a Holley 600 CFM Four Barrel Carburetor because the old one barely worked. Now I try and put it on and I come to find that I have a two barrel manifold(now is when you think I'm an idiot right? haha) so now I need a four barrel manifold and I was looking at an Edelbrock Performer and now I am wondering if I should just take off all the EGR stuff or get a Edelbrock 4-bbl EGR Adapter Plate. So my big questions are will this setup even work? Should I keep the EGR system or not? And are there any other adapters I need?

 

...well,I think you're opening up a can of worms here.Your carb is matched to several variables,not the least of which is the camshaft,with predertimed lift and duration of the valves.If I were you,I'd return the 6oo cfm holley for a new two barrel.I've had the 351M on two Mercs over the years,and found the Autolite/Ford two barrel to be more than adequate for normal around town/over the highway use...