I am restoring a 1955 T-bird which of course SHOULD have a 292-engine. However, the cylinder heads are marked ECL-A and according to literature these are from a 1955 272 Ford passenger car OR a 292 Mecury passenger car. Not in a T-bird. The bore was nominal for a 292, 3,750".
Question 1: Is there anyway to tell if this is a 272 bored to 292 or if it was originally a 292 engine?
Question 2: What is giving the different compression ratios (7.6, 8.1 and 8.5) for the 1955 variants, combustion chamber in cylinder head or piston crown design? If cylinder head, which compression will my ECL-A heads give?

The block numbers will help to identify what it was originally.  http://www.ford-y-block.com/Block%20identification.htm 

With Y-Blocks, the variation in the compression ratio has to do with combustion chamber volume and displacement.  Everything else equal,:
smaller combustion chamber = higher compression
larger combustion chamber = lower compression
smaller displacement = lower compression
larger displacement = higher compression





Lawrenceville, GA

Johan.  Welcome to the site.  There are a number of 'Bird owners on this site.  Some are not purists in the sense of having restored their cars to be 'numbers' correct.  That is not to say that they are not knowledgeable, just that they may have changed some things on their cars to improve their drive-ability or performance.

John Mummert is an excellent source of information on Ford y-block engines.  John's web site is Ford y-block.com  I often reference it because of the enormous amount of information that it provides.

In looking at John's web site, he shows the ECL 6015-A engine block as being one of the casting numbers used in 1955 for 292 engines.  Click the link below to look at the chart John has generated.
http://ford-y-block.com/Block%20identification.htm

I'd have to look at the Classic Thunderbird Club International 'Thunderbird Restoration Details and Specifications Manual to see which casting number engine blocks were used in '55 'Bird's.  My vague recollection is that '55 'Bird's had engines from the Cleveland plant.  I believe that those had the letters ECH, ECJ, ECL, and ECK.  The C.T.CI. Manual may narrow this down for you.  '55 engine blocks with the letters EDB 6015-A and ECG were cast only at the Dearborn plant.

Regarding your second question, all Ford y-blocks '54 - '64 used cast aluminum flat top pistons.  Your thought is correct.  FoMoCo used cylinder heads with different combustion chamber volumes depending upon the engine application.  One example of this in '55 and '56 was in the Mercury cars.  If the engine had a 3 speed standard or 3 speed standard with overdrive transmission, they used a cylinder head that had a larger combustion chamber and resulted in a slightly lower compression ratio for the engine it was used on.  Conversely, IF the engine had an automatic transmission, they used a cylinder head with a smaller combustion chamber that yielded a slightly higher compression ratio for the engine it was used on.

Click the link below to take you to John Mummert's web page information on cylinder head applications.  NOTE:  Some sections of the chart have more info than others, but in addition to the engine year, it will show you the engine application, advertised static compression ratio on the engine it was supplied on, and the intake valve size.  Some sections of John's chart indicate the intended volume of the manufactured cylinder head when it was produced without including the increase in volume due to the head gasket used.
http://ford-y-block.com/cylinderheadchart.htm

As I theorized regarding the engine blocks, I suspect that C.T.C.I.'s Restoration Manual will indicate what cylinder heads were used on the '55 'Birds depending whether they were a manual or automatic transmission.

The C.T.C.I Manual has been generated over a period of years beginning in 1995 with numerous supplemental sections released since it's inception.  In recent times, they have also generated an index to assist with locating information on various topics within it's 400+ pages.  While not an inexpensive purchase, I think that you'll find it invaluable as you get into working on your car.

Hope this helps.  


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Thanks, seems to be an informative page!

Thanks!

Charlie, saw that you are from New York state, this is where my Bird was sold when new! Now it lives in Stockholm, Sweden.

Hopefully your '55 escaped New York state before the climate got to it.  An awful lot of 'Birds were prematurely ravaged by the Winter weather we have coupled with the generous use of road salt to accelerate the rusting of vehicle bodies.

My apologies for having to go back and correct a few of my entries initially recorded in my posting.

Don't hesitate to inquire about what you're running into.  There are NO silly questions to be asked.  There are amazingly knowledgeable, helpful and generous individuals on this site.

Regards,
Charlie


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

1955 Bird Cylinder heads per TBird restoration manual

ECL - A  =    Automatic Trans
ECL -B = Std and O/D Trans's


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Thanks, very interesting. But now I am confused. In one way it fits perfect, as I have a 55 Bird with 292 and Auto and have ECL-A cylinder heads, spot on according to your reference (is this restoration guide available on line?). However, if I look at John Mummerts guide for cylinder heads ECL-A is a head from either '55 272 Ford or 292 Mercury both having the low 7,6 compression ratio (and not the 8,5 that the Auto Bird should have).
What is important for me in the end is that I start working with 8,5 compression heads. I guess if the literature is not consequent on what ECL-A it should be possible to determine the compression by measuring the volume of the combustion chamber in the cylinder head? Any idea what the volume is for the 7,6 and 8,5 respectively?

Johan.  Hmmmm... I took at the web site for the Classic Thunderbird Club International.  Click the link below to get there...
http://www.ctci.org/store.php

The 'Thunderbird Restoration Details and Specification Manual' is not available on line.  I dug around the C.T.C.I website to try to be able to get you to what you might be interested in obtaining for reference info.  I wasn't thrilled with how clearly they currently have things listed or presented.  To purchase any of the various materials they offer, you have to become a member of the organization. 

- On the web page that opens, look on the left hand side under the heading 'Product Catalog'
- Click on the link under that heading on the listing titled, 'Publications'
There are some 7 pages of available publications, some dealing strictly with '55 information like, 'Electrical', 'Trim & Sealer', '55 Ford & Thunderbird Shop Manual, '55/'56 Specification Manual, '55 Motorola Radio Manual, '55 FordoMatic Manual, etc.  These are excellent and many are reproductions of original Ford publications.

- On Page 5 of the listing of publications is the 'Restoration & Specification Manual', Complete Set  # 110-58FC  price is $185.00  {This is the whole thing, #110 is the main section plus all addendums A, B, C, D, E, F, G, H, I, and J]  The Manual is 479 pages and is 2 inches thick without the notebook they offer to hold it!  This is a chunk of money, but provides voluminous information with accompanying colored pictures of what is being talked about.  NOTE:  This Manual has been authored and assembled principally by long time member Gil Baumgartner.  IF you're going to do serious work on your '55 (or a '56 or '57 'Bird) this Manual will be invaluable in knowing what you're looking at and what is 'correct' and what may have been changed since the car was produced.  For anyone doing restoration work it will guide you regarding virtually everything you need to know.  This Manual has been a labor of love by Baumgartner beginning in 1995 with the most recent addendum published in 2013.  It has not been a money maker for him or the organization that has supported its publication.
 
- Also on Page 5 is a compilation of original service letters issued by Ford relating to '55, '56, and '57 'Birds.  It's titled, 'Product Service Letters '55, '56, '57' item #110-27 with a price of $18.00.  These service letters were issued by Ford to the Ford dealerships to provide additional info on how to deal with problems that surfaced after vehicle production.  Super-ceded parts are identified as an example.  In the case of the '55 292 engine, the rear seal retainer is replaced by a new number.  If you were replacing the rear seal on the crankshaft, they were recommending that you use a newly released replacement lower retainer.  -Ford changed the aluminum retainer, not because of defective materials but in favor of a different design that they believed would be better at retaining its shape.

On Page 6 is another manual that you may wish to consider purchasing.  Titled, '1955-1957 Thunderbird Illustration & Reference Manual' it's Manual #110-52 with a price of $20.00.  The manual has black & white exploded view pictures and is like looking at a parts manual.  This 124 page booklet can be very helpful in disassembling and reassembling everything and anything on an early 'Bird.
_______________________

Regarding John Mummert's chart of cylinder head info.  Yup!  Something is not correct!  An ECL-A heads on a 272 engine does not yield the same compression ratio on a 292 engine.  I don't recall seeing combustion chamber volumes listed for the earlier y-block heads in articles I've seen... 


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York