main cap bolts

[willy wagon]

can anyone tell me if the blocks are the same in the main cap and in webbing in crank cap bolt holes on the engines that use the 9/16 or the 5/8 bolts. the reason i asked one of my 9/16 bolt holes are stripped. can i safley tap to 5/8 and drill out the cap to accept a 5/8 bolt? thank-you

[Dandy Dave]

I would heilicoil the striped hole and maintain the correct size bolts. Dandy Dave!

[willy wagon]

whats your thoughts on heli-coil versus using a bigger bolt, provided factory did it? would the bigger bolt not be stronger?

[BearCreek Majors]

I’m with Dave on this one……..but, yes the larger bolt of a same grade would be stronger, and by the time you have drilled and taped the block for a helicoil you have most likely removed just as much metal as you would for the larger bolt. If changing bolt size make sure the new one is the correct grade, I’m assuming it needs to be a grade 8.

Pat

[willy wagon]

so i tapped out the bad hole to 5/8 nf. also had to drill out the cap. all had to be done perfectly straight. all went well, i did it myself. i am though a little conserned about the remaining holes in the block. it is not a small job to do them all.

[Kim]

Why do you feel the need to do all of them? If the rest are OK, just go with it. Remember, if it works, don't fix it!

[BearCreek Majors]

I wouldn’t bother with the remaining bolts ether unless you have serious doubts about the integrity of the threads.
I’m assuming the only reason Ford increased the bolt size in the later engines was to prevent failure in worst case scenario, such as engines being modified with turbo’s, higher reving truck engines, etc.

Pat

[willy wagon]

well when i see bad threads, i get nervous. why? was it put together without a torqye wrench? who knows , anyway i am putting it together, hope all is well. hope there are now more glitchs, so i can get it running before the snow flies. if it is done rite should run great. all parts are new.