[Pman1961]

Conclusion of the fasteners and the 402 headers and I'm sure will be applicable to other combinations. Originally, I ordered your typical header bolt kit with the 3/8" 12 point head as in the pictures shown in the number 1 post. The angle of the fastener trying to go through the flange was so severe it would not work because of contact of the primary tubes. Even if it were to fit I would have been unable to get a closed end wrench or socket on a few of the 12 point fastensers because of the limited amount of clearance. Then I ordered some stud type fasteners. Mistake...the washer head nut was much larger than the head of the bolt, can't recall but used a 1/2" I believe tool to tighten the stud nuts. I called ARP and got a part number ARP 100-1108. This is a 3/8"x.75 long with a 5/16" hex head. The bolts still would not go through the hole but the angle was not as severe. Spent about 10 minutes using a round file and massaged the hole in the flange so the fastener would go through. The flange side where it mates with the head remained round. I filed on the primary side ever so slightly until bolt was able to go into position. With the bolt in place there is no evidence of modification as the washer head bolt covered the hole. FYI. I did not use the supplied washers with the header bolts because they would not clear the header tubes unless you ground down one side to clear the tubes. I did not need to bang dents into the headers if you install them as follows: (Now I used copper high heat gasket maker but I would think gasket users could apply the same method) 1. Purchase some 3/8"-16 all thread rod and cut into 1-1/2" lengths 2 pieces required (could use a bolt you may have lying around and cut head off) 2. Insert these studs into the outer exhaust bolt location at the front and rear of the head. 3. Scrape and clean contact surfaces if you have not done so already and put a nice continuous bead of copper high heat sealant around the port and bolt holes on the flange of the header. 4. My car is a SPF so the following worked for me. On the passenger side you can install the header from the top of the car with the motor in place. Slip the header onto the studs but DO NOT let the headers with sealant make contact with the head at this time. 5. Insert fasteners all locations onto the headers except the obvious where the studs are in place. (make sure to apply anti-seize on threads of fasteners if using aluminum heads) 6. Push headers close enough to head so you can begin to start fastener. Start each fastener and screw them in evenly. If you had pushed the header to the heads and then tried to install the fasteners you will not be able to get the fasteners in because they would hit the tube of the headers as the radius creates conflict. That is why I put the fasteners in all the way and then tighten evenly. 7. Remove the studs and install ARP fasteners in their place. 8. Tightened all fasteners firmly. 9. Remove the excess copper high heat gasket maker where visible with Q tips and followed up with paper towels. 10. Left side or drivers side is similar but I go up through the bottom of the car. Of course you need to have your car in the air. On the left side I was able to lay the header on the frame rail then go to the top of the car and pull the headers into position. 11. Once the gasket maker was I applied I installed the headers. I did not let the gasket maker air dry for a period of time...just put it on. I hope this may be of help to someone in the future. Not difficult at all. By the way...I used a standard collector gasket between the header and sidepipes purchased from Olthoff with 5/16" x 1 1/4" grade 8 bolts, small s.s. washers each side and self locking stove nuts. Seen another thread requesting fastener information so I thought I would share.