Stainless bell housing bolts

Several years ago when I had my engine redone I replaced the bellhousing bolts with grade 8 from the hardware store. I discovered the bolts needed to be non standard hardware lengths so I cut them to length. Since I've been chasing a clutch disengagement issue so to rule out the possibility that one or more might not be allowing the bellhousing to fully tighten, I decided to order replacements from an AMC vendor. When I asked about the bolt grade he told me that he sold stainless ones. When I asked about the strength vs OEM he quipped that he's never had a complaint. I went ahead and for about $25 plus shipping ordered them. When they arrived, I tried to reference the head marking to strength grade. The results were kind of unclear but it seems that stainless would be between grade 2 and 5, although I'm not sure where exactly. Now I'm having second thoughts about their strength. This is not a 10 sec drag car, just a warmed up 390. Any thoughts?


Edited by Javelin69 - May/28/2016 at 10:03am

Good point you bring up about the shank maybe being important in the alignment. I'm feeling since I'm doing this to rule it out as a cause of my problem I should try to obtain OEM bolts. It looks like from the parts CD I've got different years are different length. It looks like I've got the correct length anyway. But being off shore non original parts the shank dimentions might be wrong.

I was surprised when I checked that stainless bolts aren't a better grade. Seems to be a common misconception. I wonder why when I've tried to work with it in the past it seems so hard.

tomj wrote: ...the two biggies with the long shoulders that do the precise bell::engine location are often not ordinary fasteners, sometimes simply a small head or something, with the long non-threaded shank that is the locating "dowel"....

This isn't correct.  The two bell dowels locate the bell with respect to the block.  The only fastener that I've ever seen that uses the shank for alignment is a pressure plate bolt.  I'm neglecting shoulder bolts as they are a special case.  As to stainless bolt identification, that isn't as straightforward as carbon steel.  There is considerable information available on that topic, this being just one.  http://www.atlanticfasteners.com/tech-tips/stainless-steel-hex-cap-screw-markings/

vinny wrote: The large bolts with the shank stepped down to smaller threads for locating the bell to the block or maybe also the starter were at least common in the older years. I remember my 64 with the 196 used them....

I stand corrected.  I was not aware of the earlier applications.

Just a note on the above post that grade 8 is always better then grade 5.  This is true in almost all vehicle applications except the exhaust.  Grade 8 alloys will harden and may snap off through high thermal cycling temperatures of an exhaust manifold or headers.  In this location grade 5 or stainless are a better option.  I personally like stainless on exhaust.  And yes some have used grade 8 on exhaust and never have had problems.  The link below is promotional but also informative.
http://hillco-fastener-warehouse.blogspot.ca/2011/05/choosing-right-fastener.html