The Stovebolt Site Forums The Shop Area Engine Shop 1941 216 engine rebuild

Hey all.
I am planning on rebuilding on of my spare engines.
It is a 1941 216 out of a 3/4 pickup. It is completely disassembled already. Having studied the 49-52 216 at great length I am noticing some minor differences. Like lack of oil seals on the valve stems, instead there is a cap.

I am assuming the umbrella(cap) on the intake valves allow more oil to flow back to the head, while with UFO shaped exhaust covers allow more oil to be retained to help in lubrication of the hotter component.

I was also suprised by the SMALL(10mm) spark plug hole. the smaller plug with the bigger gap seems strange.

The other differences that I have noticed are the manifold studs at the front and back of the head are about 1" longer than on the later head.

Is this to Bolt down the manifold on the ends?

Also the Exhaust port is straight down and the vacuum port is straight back.

Are there any other differences that I need to know about before putting this together? I have looked through the online manual and nothing really jumps out as being different except a few of the measurements. I also assume that engine performance is about the same.

I am planning on going to machined rods so that I can use inserts, replacing all the bearings, new valve seats, new exhuast valves. etc. Mileage on this engine is unknown, and the overall condtion is pretty good. I am hoping to get away with a .003 hone on the cylinders, they look really good currently.

I plan on using the motors manual for the 216, and the shop manual for 1941.

I will have a local machine shop perform the head work, I will do everything else. I have thought about a few performance mods, but only if they were available when the engine was new.

- A rubber-cap for a valve stem seal is a popular replacement for the standard o-ring-type seal (the style that usually comes in a gasket set).

- Spark plug sizes changed sometime in 1949

- The longer the manifold end-studs in the head, the greater the limitation on clearance at the firewall end. On 216/235/261 engines these studs are for alignment (I think) and to aid in installation (the outer end of the stud was not threaded).

- Here are hp ratings (taken from Shop Manuals, etc) (Note: different GM documents in the same year often show different hp values)

- The exhaust outlet on the exhaust manifold was straight on all 216s and on 235s through 1949

Thanks for the reply.

The straight manifolds must have stopped with the dec 48 engines,
my 4 1949 engines from flint( 2 Jan-feb, the others May-jun) all have the angled exhaust manifold.

The studs on this head are the long threaded studs. Where does the 49 and later pick up the extra 2 horse power? are the valve different, or is the crank ground differently?

Is their a disadvantage to using the metal valve caps? I wouldn't think so.

THanks for the help.

Somewhere I have a GM instruction explaining a conversion from the old type cap to the newer valve o-ring seal. It seems to me that the grooves on the valve stem are different.

If your motor has the domed pistons, the combustion chamber would have changed in the later 216s. That may have made the performance different.

I think the biggest difference on the valves is the single and double groove, and I think the single groove valves are slightly shorter to accomodate the caps. I will have to check for the domed pistons. IU would think it would make a difference. I will rpbably just leave this one stock after thinking about it. You just don't see a lot of stock engines anymore.

There is nothing wrong with that motor. They did a pretty good job.

1941 has flat top pistons.
1940-41 cranks, which are the same, have a larger flywheel pilot than 1942-62 and use 3/8" retaining bolts, 1942 and up are 7/16".

my gosh I could not type yesterday. Forgive my typos.

Now I just need to track down 1 of those exhaust caps(missing)

I figure this head configuration was on the WW2 chevs, so they must have worked pretty well.

I will post some pics when it is done.
Thanks all.