6 VOLTS/POS. GRD. NW INDIANA

I am in the process of installing an oversized remote power brake booster (for the first time) which will limit access to the exhaust manifold bolts on the drivers side (55 Tbird).  Did you have to re-tighten the bolts at any time after you installed them?   I am not going to be able to start the car for a couple of weeks, due to other projects.  The spec for the bolts is "not to exceed 20 lbs", hex key is 6 lbs/72 inch pounds.

6 VOLTS/POS. GRD. NW INDIANA

I am going to try Summit Racing™ Split Lock Bolt Kits SUM-910120.   They have an internal Allen bolt that spreads the end of bolt to hold it in place.   I bought some thick hardened washers because these heads are also too small for the manifolds.  I am going to put some anti-seize on the internal bolt

____________________________

By design, there are larger holes in the exhaust manifolds to allow for heat expansion of the manifold.  Typically one hole will be smaller than the rest just so that the manifold is positioned correctly to the cylinder head.

Here’s a link showing a video where the wedge-locking washer technology is tested at a 4000 lb. clamp load.
Bing Videos

And here’s another option for a positive locking bolt where the exhaust manifold bolt holes may be too large for a conventional lock washer.
 

Lorena, Texas (South of Waco)

I liked this solution.  I bought a set of Procom header bolts that come with similar washers.


Unfortunately the heads of the bolts (3/8 16) were too small for the holes in my manifolds (For some reason the holes are larger, except for the hole in the middle). 
   

The heads are all 3/6 16 threads.   Does anyone know if the bolts are supposed to have a shoulder to make up for the larger holes (my bolts do not have a shoulder)?  I wonder if all this play causing the bolts to come loose????
The picture is one of my original 1955 292 manifolds.  I bought a set of reproductions and they are drilled the same

I have been using Nord Lock washers on the headers on my FE powered 1966 Fairlane and they do a good job in keeping the header bolts from backing off.  Here’s a picture of what they look like.
 

Lorena, Texas (South of Waco)

The exhaust manifolds on my 55 Tbird weren't leaking when I started tearing down the engine, and no broken ears. They are the original manifolds. 

The only y block I have seen that the exhaust manifolds didn't leak as you described had the factory style lock washers that you bent around the sides of the bolt heads to keep them from turning. I just chalk re-tightening up to routine maintenance on these things.