Need Help With Assembly Issue

[AutoInsane]

I have a 7/16 14 hole in the front of my cylinder head (1974 CJ5 w a 304 V8) that I need to screw a 3/8 16 bolt into. It will get torqued to abt 25lbs. The bolt goes through a bracket that holds the alternator on. It then goes through the top hole in the alternator.

The don’t make an adapter, coupling nut reducer or a step stud that will work from my research. A 7/16 male to 3/8 female adapter would be perfect if one exists! Or even a 7/16 to 3/8 step stud....

I cannot just put a 7/16 14 bolt into it due to the bolt length being 7 inches and needing to be a socket cap and not hex. There isn’t room for a hex head with the blades on the alternator. I might do a 7/16 to 7/16 stud and then use coupling nut(s). This would require drilling out the bracket and hole on the alternator.

I could drill/ tap the hole but that is a last resort.

Any thoughts?

[JKZ27]

Maybe a 3/8" Helicoil or a Time-sert? Either may require about a 7/16" threaded hole.

[big gear head]

A 3/8-16 helicoil will have 16 threads per inch on the outside, not 14.

The reason you will not find an adapter like you want is that the minor diameter of the 7/16-14 thread is .360 and the major diameter of the 3/8-16 thread is .375. If you try to cut 3/8-16 threads inside a 7/16-14 bolt the 3/8-16 threads will actually cut through the root of the 7/16-14 threads. I just tried this to see if it would work and it didn't. I took a picture, but couldn't upload it where I am right now.

[PeteLeathersac]

'

Can you drill the bracket also alternator hole and use a larger size socket/cap bolt?
Even if the cap head was slightly too large, could you machine the outside down for clearance?

Is this bolt the one the alt' pivots on or the adjustment/tightening bolt?
If adjustment bolt, is there enough meat to make the alt' hole larger or oblong so bolt sits off ctr. w/ head further way from blades when tightened down?

~ Pete

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[Thomas]

Drill and tap for a 1/2' thread and then use a 1/2" to 3/8" threaded insert.