the chevy dealer doesnt know the size, does anyone know what size bolt to get? I dont want to take the hood down to the bolt place unless i have to. I need the size for the 4 bolts that hold the hood onto the hinges.

Take one of your rad support /fender bolts out and try it. I think they are the same.

You got that engine in there yet? Try a 5/16 course thread bolt in the hood. I think they used a fender bolt originally but a bolt and lock washer should work. Of course the last time I worked on a 70's Chevelle, they were new!

Make sure what you use is not too long or you will be really pissed at yourself!

Engine is in and done, got the exhaust system put on today. found the bolts (3/8-16 x 3/4) and put the hood on. just got back from a drive. it moves nice, just havent got on it real hard yet. ill give it a little time to break in, then ill light it up

I doubt it needs much breaking in. I broke it in pretty good on the dyno, and then made several pulls :