Classic/Antique Car Repair: Classic door hinge bolts, door hinge, machine screw

Question
QUESTION: I am looking for grade 8 door hinge bolts.  I have a 1936 Pierce Arrow and cannot find the straight slot bolts to replace in the door hinges. I think they are about a 5/16 x 4"
Can you help.
Also, how do you adjust to door to close properly?
Thanks

ANSWER: Is this a counter sunk head screw?

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QUESTION: I don't know the names of the ype of screws, but the head looks like a very heavy duty wood screw type with a straight slot.  It has machine threads though.

Answer
I think that what you are looking for is called a machine screw. I use a company called Fastenal as they have stores world wide. On line you can find them at www.fastenal.com. I would suggest that stainless be used. Now these bolts usually went through the door hinge and then the sheet metal. There was usually a piece of 3/16ths behind all of this that sandwiched the body and squeezed the door in place. And this whole mess is allowed to move around as the holes are slotted to allow adjustment.
Brad