Should I chisel out my door jambs if the old hinges weren't flush?

Those surface-mounted hinges are likely what we call "no-mortise" hinges, or just a lazy shortcut from a builder who didn't want to spend time on the millwork. The problem with switching to solid-core doors is that those extra 30 or 40 pounds put a massive amount of leverage on the screws. If you leave them surface-mounted, the hinge plate is essentially trying to peel away from the wood rather than being supported by the pocket of a mortise.

Since you're already doing the work, you should definitely **mortise the hinges** into the jamb and the new door slabs. You don't need to be a master carpenter to do this, but skip the hammer and chisel if you're nervous about it. Go to a hardware store and pick up a plastic hinge template and a small trim router. The template clamps onto the door or the jamb, and you just run the router inside the guide. It makes a perfect, professional-looking recess every single time. It's much harder to screw up than trying to chip away wood with a hand tool.

Regarding the weight, you realy should consider adding a **third hinge** in the middle of the door. Two hinges can handle a hollow door easily, but solid-core slabs tend to warp or sag over time if they aren't supported in the center. Even with three-inch screws in the top hinge, you're putting a lot of faith in a single point of failure. Adding that third hinge while you're already routing out the other two only takes an extra ten minutes and saves you from having to plane the bottom of the door in two years when it starts dragging on the floor. If you absolutely refuse to mortise, at least make sure you're using heavy-duty screws that reach all the way through the jamb and bite into the **wall studs** behind it. But honestly, if you're upgrading to solid doors for soundproofing, you want a tight, square fit. Recessing the hinges is the only way to get the tolerances right so the door seals properly against the stop.

Spot on about the template and router. It makes the job way less stressful. One thing to watch out for when you're moving to solid core is 'hinge bind.' If you don't mortise deep enought becuase you're worried about hitting the wood too hard, the door will acutally spring back open or put even more pressure on those screws.

Also, when you're driving those 3-inch screws into the studs, make sure you pre-drill a pilot hole first. If you don't, the extra torque from a solid door can actually split the jamb or the stud behind it, wich is a total nightmare to fix.

Router templates are fine for the new guys, but a sharp 1-inch butt chisel and a wooden mallet haven't failed me in forty years. If you go the manual route, just score your perimeter with a utility knife first to keep the grain from splintering. I've seen too many 'quick' router jobs end with a slipped bit and a ruined jamb. Also, check the hinge pin diameter. Those cheap no-mortise jobs ussually have thin pins that'll snap or bend under a solid slab. Swap 'em for some real 3.5-inch ball bearing hinges while you're at it. Your back and your floorboards will thank you later.