what is correct bolt,washer combination for external engine fasteners?

[70 RAG TOP]

Is there a reason why the actual bolt holes are a size bigger than the threaded hole(ie in the intake man. mounting bolts, the exhaust manifold, and valve covers?  Wouldn't that allow for unwanted movement and gasket leakage?

My 2nd question is: What do you guys usually use for washers?

The regular washers that fit a certain bolt are so big in diam that I think it looks like crap with all that excess washer showing. 

Do they make flat washers that are smaller in o.d but with the correct i.d. for the bolt in question? 

On the intake for example, would you use bolt only, bolt and flat washer, bolt and lock washer only, or bolt, lock washer and flat washer?   

Thanks

[4 speed fish]

Just use bolt and lock washer.

[72cudamaan]

Bolt holes are bigger to allow for casting variances. When tightened properly you wont get enough movement to distort the gasket.

Try someplace like Mcmasters or Fastenal for washers with the proper o.d

I wouldn't use lock washers on most engine fasteners. Might though on the accessory bolts such as alt. pivot or power steering.

[burdar]

Most engine fasteners from the factory had a head with a built-in washer.(or captive washer)   Having loose washers on an engine assembly is an accident waiting to happen.  It wouldn't take long in a factory environment for a loose washer to end up inside an engine.  Like was said above, hole sizes are for casting differences.