When removing my exhaust/intake manifold on my 226 flat head six I broke the middle stud between the exhaust ports on cylinders 3 and 4. I ended up having to drill out the stud. I have two questions:

1. After drilling out and removing the stud I noticed a smaller hole that goes back into what can only be the water jacket. Is it normal for this to go back into the water jacket? I can't tell if this is a casting problem or if this is supposed to go into the water jacket and a portion of it is filled with 55 years of gunk. The hole that goes on back is smaller than the 3/8" threaded hole.

2. The threads are pretty rough, some of it is because of the years, the other is my doing some damage with stud removal. There are threads but they are not very tight. Should I use some a helicoil or other repair device or is there a recomended thread repair epoxy that will stand up to the heat.

Suggestions are appreciated.

 

I also have the front stud broken off on my 226 manifold, its not leaking yet so I haven't removed the manifold. When I first fired up my 226 the flywheel came loose and messed up the threads, I retapped them and installed new bolts. I used the Locktite liquid called bearing mount. I managed to torque them and get the lock wire back in, I have driven it around 3,000 miles and its been ok so far. Its hard for me to say how I would proceed on yours without seeing the threads. A Heli Coil is an option, or you could look at a Metric stud just a little bigger. I don't know about the smaller hole into the water jacket you are refeering to, at least till I get mine apart. Those studs take 30-35 lbs of torque, so you could put the stud back in and put some flat washers on it then torque it down to see how it holds.

Sorry I can't be of more help
Rod

 

The heli-coil will work, as will other brands of threaded inserts - if you have enough surrounding material.

If you don't want to go that route, I've used class 3 threaded fasteners to "tighten up" a threaded connection. The studs and tapped holes were probably originally a class 2 thread - a medium tolerance fit. A class 3 stud (a close tolerance fit) would produce a somewhat tighter fit with the block IF you could find somebody selling them. I got my class 3 fasteners through an aerospace company at work. You may have to search around a little to find somebody selling class 3 fasteners or threaded rod of the right size.

I've also bought a round, split die (any tool shop or McMaster-Carr) and cut threads on a blank steel round to form a stud. If you don't tighten down the die handle adjustment screws (the screws in the die handle that close the split in the die), you get a thread that is the correct pitch but a little larger diameter than standard. You have to make sure you use a good quality cutting fluid to get quality threads. I've only done this in a head bolt situation where I didn't think I had enough extra material in the block to drill oversize and install a heli-coil (or similar) thread insert. It works very well if you want to take the time to do it.

 

Third Coast, I have some intake/exhaust studs from a 226 block I stripped down for parts. They are probably the same size as yours, but if you want to take a Caliper and give me the specs on them I would check them to see if they might be a little bigger. I't just a shot, but you never know.

Rod