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Engine Identification

What engine do I have?

You have a new engine,  or you are considering purchasing one,  but you want to be sure it's the correct engine,  the one best suited for your needs.  The only real way to know for sure what engine you have is to locate the engine codes and reference them to a reliable source.

The 3 worst ways to identify an engine:

1. Look up the VIN.
2. Check the registration.
3. Ask the seller.

The Corvair is a very simple automobile.   It's not been in  production for over 30 years,  so chances are your engine has been around for quite some time.  Since they are so simple to work on,  and since they've been around for so long,  the one you are considering or already own has probably been wrenched on by more than one questionable mechanic.  Unless you bought the car yourself from the dealer,  or are positive of it's history,  the VIN or registration could be very misleading.   The 1968 car from which you pulled your engine,  may have had a 1963 engine installed it in 20 years ago.  Additionally,  the person you are purchasing it from,  may not be as knowledgeable as you hope.  He may be going by the VIN or registration.

So just how do you identify the engine?  You have to find the identification codes.

There are 3 different locations for these codes:
1. Stamped on the case.
2. Cast into the head.
3. Cast into the crank.


Locating only one of these numbers is not conclusive.  We are all after the same thing.  We want a late (1964-1969) bottom end,  with high compression heads.  This comes in many different packages, but the bottom line is that any late crank and case end will do.

The case can be identified by it's stamped number,  but there are a few vague years.   The one or two letter suffix identifies the engine year,  HP rating and transmission used.  But the confusion comes in when the same suffix is shared by both early and late models.  In this case,  the only way to determine if it's the right case,   is by removing the blower housing and looking for the crank number.

There are 3 crank numbers I'm aware of:
5607 signifies it from an early engine.
7293 signifies it from an early turbo engine.
8409 is the crank we need.  It's from all the late engines,  regardless of HP.


Now that you've determined the year of the bottom end,  you now need to identify the heads... both of them.  It's entirely possible to have a case number which says the engine is a 1968 110hp engine,  but it could have 95hp smog heads,   or even worse,  they could be totally different from one another,  having different numbers and compression ratios.  

The way to identify the heads is by the number cast on one end.

 

Now that you've found the numbers,  you'll need to look the numbers up to see what the signify.  I've copied tables from Clark's catalog. Click on the links below to view the tables.
Head Code Numbers
Case Code Suffix

 

casehavs.jpg (46598 bytes)

Here's the case identification number.

 

head3.jpg (66889 bytes)

Here's the head code number.

 

cranknbr.jpg (53439 bytes)

Here's the crank code number.

 

Now I know what engine I have,  but it's wrong.

 
So now you have a pretty good idea of what engine you have.  If it's the correct one,  congratulations.   If not,  you may be looking into some alternative action to take.

If you have the correct crank and case,  but not the right heads,  it's easy enough to change them out.  If you  have 140 heads,  or smog heads,  you may be lucky enough to sell them to a car engine builder,  as these heads are more desirable for automobile applications.  In the case of the 140 heads or turbo heads,  you may even make a buck or two in your transitioning from these heads to the 110 heads.  

We are fortunate that the car guys really don't place a high value in the 110 heads.

On the other hand,  if you have the wrong crank,  you are going to have a harder time.

But what's the major difference between the early case/crank and the late?   Bore and stroke.
1. Early cylinder diameter is smaller so new cylinders won't fit in the case..
2. Early crank stroke is shorter so it can never make 164 cubes.
3. Early case can't physically handle the late crank without alterations..


It is possible to put a late crank in an early case,  and to install late cylinders in the early case too.  But it's a lot of work.  The cylinders are larger in diameter,  so the obvious answer is to fly-cut the cylinder bore in the case.

But the real kicker is in relieving the case.  The width of the case is very narrow.  When the piston is at bottom dead center,  it's connecting rod is very close to the opposite side of the case.  In the early case,   with an early crank,  this is not an issue.  But the stroke is longer in the late engines,  and if you try and put this longer stroke crank in an early case,   the connecting rod bolts (nuts) will hit the inside wall of the opposite side of the case.

 


Here's a photo of the early crank.   Notice how much distance there between the bottom of the bearing surface and the edge of the casting.

cranknbr.jpg (53439 bytes)

Compare this to the late crank:

LATECRNK.JPG (54122 bytes)

This shows quite dramatically the specific difference between the early and late cranks.

 


As stated above,  the case needs to be machined to allow the connecting rod bolts to not come in contact with the case. The photo below is of an early case.  The arrows are pointing to the part of the case which would interfere with the connecting rod bolts from the opposite cylinder.

ERLYCASE.JPG (60950 bytes)

Notice how this area is completely flat.

 


The photo below is an extreme close-up of a late case,  and shows how it needs to be machined to accept the longer stroke of the late crank.   The case was cast (at the factory) with this depression,  but if you wanted to take the time to relieve your early case in this same manor,  you could safely get the late crank to fit in the early case.

ERLYCASE.JPG (60950 bytes)

Another view...

CLOCRNK2.JPG (71490 bytes)

CLOSCRNK.JPG (73782 bytes)

 

If you have comments or suggestions, E-Mail me, Patrick Panzera