Cadillac adjustable rockers...

I picked up an early Cad motor the other day ('49-'54) that appears to have been sitting tarped up in the same spot for at least 30 years.
I pulled off the flaking chrome valve covers just to see what I could see, and was met with a set of Thomas adjustable rocker arms. They appear to be magnesium, but Im not positive. Does anybody have any info on these?

 

I agree with removing the rocker shafts to protect those rockers. I have a set of these and would be interested in seeing the valve cover set up you found on your engine.

 

Those are beautiful...

 

Thanks for the info, Ill pull the rocker shafts before I attempt to turn it over.
The engine had a factory tri power set up and stock (chromed) valve covers just sitting on it. Ill go out later and check if the covers clear the rockers. Ive heard of people getting away with using 2 gaskets to gain clearance, but this didnt have any on it.
I believe the motor was in a boat...it has a flexplate mounted up front to the balancer with a home made starter mount on the drivers front corner. Out back there is some sort of a small gear box that bolts to the crank and has a shaft with a sprocket on the other side...strange set up.
The oil pan has no sump, its just 3-4" deep front to back, maybe for clearance to the hull...

 

Congrats! Must been gorgeous view to see when lifting the valve covers.

 

I couldnt stop smiling, it made my day!

 

, does the magnesium get brittle over the years ?

are those CV8 ?

 

Looks like it has some type of exhaust header adaptors on it too? for boat manifolds?

 

They where brittle and broke when they were new. Was common of these type of rockers.

 

The exhaust adapters dont appear to have ever been used. At first I thought they were part of a boat type water cooled exhaust, but it looks like they were intended as a transition to a round header tube.

 

MTABike...
The stock covers hit the rockers just before they bolt down without a gasket, Im thinking maybe 2 gaskets would do it. There were no visible signs of contact inside the covers.

Little Wing...
The rockers are marked C-8...Dont know if these are the standard ratio or the Hi Lift versions? I have heard that magnesium is brittle.

skidmarks...
Im curious to see what cam is in it, the springs look a little heavier that Ive seen before on stock Cads...I did pull the valley cover...no roller lifters : (
Unfortunately there was no distributor, but there was an old Mallory Magspark coil (the box type with the 2 round ballast resistors and a can type condenser) mounted to the engine.

 

Magnesium doesn't break down over time. Its just not extremely strong right from the start. It does lend itself to casting and is very lightweight, it has a good strength to weight ratio. You'll see bigger fillet radii in cast items to give them more strength. It was used extensively in aircraft to cut weight in stationary engine components like cylinders and the block itself.

Bob

 

magnesium is basically rotting from day one.

 

Wrong.

Magnesium is highly corrosion resistant since it gets alloyed with aluminum, zinc, silicon, etc. It does very well in service for engine parts in aircraft, the oil exposure protects the surface from oxidation.

Bob

 

Thomas advertised them as magnesium back in the day.