That should do the trick... The LTx bolt from GM is longer than the bolts used in older SBC's. Likewise, the LTx HUB is longer than the SBC hubs when measuring from the bottom of the hub (which bottoms/pushes against the reclutor wheels and sprockets) to the inner surface the bolt/washer bottoms against. It's only about 3/8" difference or so, but it DOES matter.

A)It seems that Callies/Compstar have:
1) decided to drill a shallower hole than in years past (Callies cranks used to have a LONG deep crank hole), more to the same depth as SBC/LT1 cranks.

2) decided to thread only about 1" of thread. I ran a tap through the threads that were there and was able to cut a little more than 6 threads into the hole that was there. I was actually quite suprised how much thread wasn't there.

B) It seem that ATI has:
1) decided that a LT1 hub should have the same bolt length as a SBC. Their hubs, as measured from the hub bottom to the bolt surface is 3/8" less.


So what's the issue? well, Callies went short on the threads, ATI lowered the bolt mount surface, and NOBODY decided to mention the LTx bolts are now too long.

If you order any hub or crank that isn't stock GM, this definitely something you should measure. I tapped my crank a few more threads, and went with a SBC bolt from ATI (which is suspiciously short IMO). The ARP bolts are high quality, but definitely too long if used with a ATI hub (though still not long enough to use it to drive on the hub) and a short crank hole.

Take home lesson:
1a) measure hole depth
1b) measure thread depth (put a bolt in there and install until threads bottom out.
2) if "b" is signifigantly shorter than "a", you may want to tap the threads deeper (not a great idea IMO if you can avoid it).

3) check the hub length vs stock... is it shorter? you may need a shorter bolt
4) use a hub installer to bottom it out, then use a long bolt to find out the end of the threads... measure the distance from the top of the washer to the bottom of the bolt head... this is a MINIMUM distance that the final bolt needs to be shorter than the long bolt you used to find the bottom of the threads. You'll probably want to make it 1/4" shorter than that just make sure you're not bottoming the threads.

BTW, the crank snout from Compstar may have been a bit narrower than stock as well... I was able to mount a brand new ATI hub onto the snout with NO honing... just antiseize and some slow wrenching (probably about 80-100 ft pounds most of the way). If you use an aftermarket crank MEASURE IT first, and be careful not to overhone the hub.

NEVER use a lock-washer (saw that mentioned above), it simply won't work and once it compresses and over heat cycles looses its resistance, the hub will be loose.

Red locktite shouldn't be nessesary. If you do use it, you'll have a hell of a time cleaning out those crank threads. Rely on the hub's interferance fit and the bolt's clamping force should be more than enough (remember, many SBC hubs stayed on fine for years without ANY bolt).

My hub's been fine now for a while, but I thought I'd share what I found out abotu ATI hubs, their suggested bolt length, and my aftermarket crank. Everything looked great on paper, and even seemed to mock up alright, but the hub was just a touch loose and that was enough to get it walking at high rpms.

 

I used the same technique, but the backlash seemed pretty tight when I stopped... the issue I had was the bolt was just a few threads to long when everything finally bolted up. With a dual-key hub I have a feeling the dual-keyed reluctor ring wasn't wiggling like it should.

Just something to watch for with a dual-key design... the CPS wiggle technique may not give great results. I now prefer to bottom a long bolt out and measure the MAX bolt length possible for that hub/crank combo, then go about 1/4" to 1/2" shorter just to make sure.

BTW, fairly heavy anti-sieze on the new hub andf keyway made installation (per ATI's reccomendations) much smoother compared to the small dab I used before. Since the hub doesn't spin on like a bolt in threads would, its nessesary to anti-sieze the full circumference of the snout and keyway(s). Antiseize on the install tool (or bolt threads and head/washer if that's your style) also helps.