A couple of years ago when I changed the water pump I spent a day while all of the accessories were off and checked each hole for the thread size and depth. For the alternator bolt it was 7/16 course thread. A 1/2 inch would not fit. There is more to the story.. see belowtedlovesjeeps71 wrote:Pull it off and see if a similar bolt will thread without the alternator stuff. Maybe try running a tap to see if that helps. Last resort would be a helicoil like C said.
When I swapped the engine I had a 3/8" bolt from my 81 Wagoneer 360. This 401 came out of an early Jav. I think I messed up the threads by using the wrong bolt for a while.Stuka wrote:That seems like a tough bolt to strip out. Its cast iron, and its torqued that high. If the bolt won't thread without the alternator, then your only option is to helicoil if there are some threads left, or pull the head and have it fixed by a machinist.
It's not bottoming out. When I spent the day checking all of the accessory holes I confirmed the depth of each one as well. It's possible it bottomed out and then the threads stripped. Right now it 'feels' like it is just getting tight and then lets loose.tedlovesjeeps71 wrote:Any chance you left off a washer(s) or spacer and it was bottoming out?
I think this is what got me. The smaller bolt kinda worked originally and I think it messed up the threads. Now the larger bolt won't hold.derf wrote:There are two bolt sizes.
The 360s I've had were one size. The 401s I've had are "one bigger". I don't recall the sizes offhand.
When I went to use the 401 with a later alternator bracket I ended up using a step bit on the bracket and it all went together fine.
Stuka wrote:Just know that drilling the alternator may prevent you from using it as a core return when you need a new one. And that if one fails someplace where you don't have a drill, that could suck.
I think you ultimately need to tap the hole to be one size larger.