I rarely disagree with Ross. But this is one of those times. The lock washer will not likely help. Its not the bolt loosening up (assuming that that was the root cause) - its the gasket compressing and causing the bolt to lose it's crush/preload. Same result - bolt gets loose - just a different cause. Putting a wrench on those fasteners every so often is a perfectly good "cure" and you'll get a good results - especially if it has not been done for a long time since assembly. But keep in mind that its not a forever cure.
Assuming a certain amount of torque or tightness applied to the intake bolts upon assembly, every time that intake expands and contracts from heat cycles it is going to try and move/bend. The only part in the assembly that can accommodate this is the gasket face - so the gasket gets subjected to a fair amount of movement stress over time. The standard Fel-Pro gasket like you have incorporates an embossed steel lined layer and can handle a great deal of movement and will still retorque nicely when it gets compressed as those embossments lose their shape.
Compare that to the paper with silicone bead Fel-Pro race gaskets, which initially seal well but are very unforgiving in terms of movement, tightness, and oil soaking. On those, the silicone bead is less compressible than the paper base, so it embeds into the substrate acting like a "cutter" with each tightening or temperature cycle compression. Couple that tendency with the FE oil soaked design that compromises the paper, and you have a recipe for the oft shown failures - and a gasket that can actually get worse with additional tightening.
If you are looking to the "right" way to design intake gasket interfaces you can check out how they do it on newer engines. They'll use a sealing bead or o-ring inserted into a plastic or metal carrier. The carrier will have hard stops for the fasteners to torque firmly against insuring that they stay tight and that compression of the sealing surface is as specified and is allowed to be separated from the tightening pressures. Completely different sealing strategy. I'll stick to my old stuff, but its good to see that they recognize and resolve the same problems at the OE level that we see in the driveway.
