I have a nice 455 block but it fell and cracked 1 of the dowel pin bosses. It broke off half the boss so the dowel pin will not stay in place. The other boss on that bank is fine. What are my options? Can I run it with just 1? Can a machine shop drill another in a different location? Maybe mod the block and head to do 1 dowel like a BBC?

 

First, you should post a pic of the damage.

 

One of the dowel pin bosses on the 455 I rebuilt broke. I installed the head with only 1 dowel pin and it was fine.

 

 

Personally, I would remove the loose pieces and loctite the pin into the head so it still locates on that side. Once the head bolts are torqued, the pins don't really do anything.

 

The engine in my car had a broken dowel pin hole, and missing pin when I took it apart. It also had one broken bellhousing bolt hole.

I had the block welded, and then decked the block. That was 20 years ago, haven’t had any issues.

 

I would get rid of the broken parts and then maybe loctite one of the pins into the head. It looks like there is enough of a step at the bottom of the hole that it couldn't go anywhere once it was in place. I dont know how close of a fit the head bolts are to the gasket holes and how close the gasket matches the bores. Like Joe said all it really does is keep stuff lined up until you torque the bolts. I just took apart a 440 Chrysler that did not have any in it and I think it has been that way from the factory.

 

If you put the pin back make sure it mechanically can't fall out once it is in place, I wouldn't rely on glue holding it there forever. Once it is on and up in the head it may not be possible for it to fall out, check it to be sure. What about just tacking the gasket in place with a dab of sealant around that pin are and then installing the head without the pin?

 

Let me add a bit to Joe P's idea, which I think is the best solution.
1. Realize that more than half the dowel pin remains. While this is not much to retain a dowel pin, its enough to locate the cylinder head for assembly.
2. I would probably use Loctite to keep the dowel pin in the cylinder head.....but, I would use a hard, pointed punch to indent the dowel pin for a light press fit.
3. One punch mark at the end of the dowel pin and another punch mark 1/16" from where the dowel pin would stick out of the head. Do this every 90 degrees.
4. Clean the dowel pin hole and tap in the dowel pin.
5. you can re-indent the pin in the same spots to get a desired fit.
.....Just my two cents worth.

 

Just want to add that if you use Loctite the Green retaining type is the one to use.