Time to change two heads around

Builders,

In the previous story; Photo Observation Contest., most people quickly picked off that the assembled engine had the heads on the opposite sides of the motor. The second question is how long did it take to correct this?

.

There were a wide variety of estimates, but first lets examine a few fun internet myths;

.

On a car, the heads have the same casting, but they are not really interchangeable right and left. The reason why: there is a 3/8″ diameter breather tube in each head just below the stock carb flange (these are machined off when we weld head pipes on) both of these tubes point toward the flywheel in a car. The are hooked together to for a balance tube and the PCV system in the car. It is common to see people building a car engine forget this, because it is less obvious than a welded on intake.

.

Second, I was always amused to see people who claim to be very experienced engine builders on the internet, when seeing a report of a temperature variation on left and right banks of a flying Corvair, quickly pontificate it must be the engine is somehow using two left or two right heads. The Corvaircraft internet group archives have numerous examples of this. Of course its moronic because the castings are the same L and R.  This isn’t unique to Corvairs, virtually all classic American V-8 and V-6 engines, including diesels, use the same head on both sides, but this basic fact wasn’t known by a lot of internet experts.

.

On the subject of reversing the heads on the motor shown, there was a little more involved, because if you look close, the rockers are already on and the valve adjustment is already done. This in mind, the task breaks down into several group tasks:

.

Remove the rockers, balls and pushrods from both sides.

.

Un-torque the heads, lift the push rod tubes, and lifters.  Remove each head.

.

Reposition the engine on the stand with the head facing up. I do this because I don’t like torquing heads with the engine on its prop flange or with it in the installed position if I can avoid it.  Not only is it simpler to work on in the 90 degree bank flight position, it keeps assembly oil from the cylinders from flowing under the head gaskets before they are fully torqued.

.

Reinstall each head, and torque it into place.

.

Reinstall the valve train, and reset the valve adjustment.

.

.

About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: