Short block 6.9 will take 7.3 heads???

[icanfixall]

Mr Roboto... First of all to make a 1/2x14 bolt you will need to turn it on a lathe because nobody makes a die nut in that size and thread. There is a big differance in the bolt body size between a 7/16 and a 1/2 inch bolt. Now just if you were to turn down a bolt that had a 1/2x14 thread instead of a 7/16x13 thread the body diameter will be too big to fit thru the head where the 6/16 bolt fits. Now if it was a stud then maybe it might work because the 1/2x14 threads would fit into the block and not need to pass thru the head. But still the block can't be drilled to fit the 1/2x13 or the 1/2x14 threads. Not enough metal left after drilling. Fabricating a fully machined special bolt that has been turned on a cnc lathe still wont work because nobody has a tap that will match this special bolt you have made. Just buy the arp studs. They will work fine.

 

[Full Monte]

That is for fitting 6.9L heads on a 7.3L block.

I beleive the eBay seller was a little overzealous in insinuating that the 7.3L heads would bolt onto the 6.9L block. It can be done, however spacers would need to be machined to take up the extra space, or else custom studs would need to be made with 7/16" thread for the block and 1/2" thread for above the block.

Good catch...I shouldn't write before I wake up.