RPOL68

I have a 69 tri-power and this happend to me, only the crack was the full length of the bolt hole and the piece was lost on the road.

I did a repair in the car with a coupling nut to replace the missing piece. I used a heat lamp to warm the area over night. I used a welding blanket to protect the firewall and wiring. I cut the coupling nut in half lenghtwise and ground and filed it for a reasonably contoured fit to match the block using a slight V. I then heated the area with an oxy-acetylene torch and pushed a bolt into the existing threads and then placed the coupling nut over the bolt threads and against the block. This lined up the threads and I braised the nut to the block, from the top down using just enough heat to do the job. I then removed the bolt, chased the threads with a tap and all was well. I was able to get to both the front and the back sides and it has held for the last 10 years with no problems.

My guess is that this happend to me because I had a loose bolt but it can also happen if you don't use the proper knurled starter bolts or front support bracket.

R1234

Yep, back in high school I had just finished rebuilding my 1970 SS Nova motor. One of my buddies put the starter on and did not tighten it up sufficiently which caused the outer bolt hole to break off. Man, I was sick.
Luckily, another buddy had one of those old chevy cast iron bellhousings that allowed for a starter bolt up. Good luck with whatever you decide to do.

The3

So how do you prevent this from happening?

Solid LT1

High Nickle rod or a powder torch are commonly used in cast iron repair, the problem is the iron will stress crack while cooling if it isn't stabilized by putting it into an oven for a slow cool down period, that being said, you may want to try doing it or some brass/silver brazing rod to perform the repair. I had a 440 Mopar crack it's starter mount one time (while it was in the machine shop) we used the high nickle rod for repairs without stabilization, it worked well. Like a previous poster said, the early 55-57 Chevy had a bellhousing mounted starter and most scatter shields still have provisions for mounting a starter motor to the block plate.

L-82kid

I found a hot rod/ custom bike shop in my town and the owner is suppose to be experienced at welding everything. He said he could fix it on his lift without pulling the motor, he has done it on a few other cars over the years. this guy is suppose to come to my place within the next few days to check it out. If he thinks he can do it, my buddy has a flat bed truck and I'll bring it to the shop and pay him to do it. I'm hoping its not too pricey and everthing works out.