Hello gentlemen,

There's probably a simple answer to this, but...on their '56 312 Y-block, how come Ford designates a 9.0 compresson ratio for an automatic tranny, but an 8.4 for standard? (in 57, those numbers are 9.1 and 9.7).

Also...I have read where the baby Birds came stock with a pretty strong Dana 44 19-spline rear end. But in 'The Book of the Ford Thunderbird' by Brian Long, it says that they had a Spicer rear axle with a 3:73 on manual models and a 3:31 on the automatic.

Any input is appreciated. Thanks.

Joey:

The higher compression was to help make up for some of the power loss with the early automatics.  You couldn't lug the engine, so more compression and more spark advance was possible without detonation.

Spicer and Dana axles are the same thing.  Dana-Spicer was the name of the company that built them.

John - "The Hoosier Hurricane"

The Dana/Spicer rears also came in station wagons. As you probably know, all the cars, including the TBirds, went to the 9 inch in 1957.

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

What method was used to achieve the differetn compression ratio?

Different cc in the heads. The smaller, the higher compression ratio.

Kenneth

Fredricksburg, Texas

So what Ford did was to put different heads (or at least different grinds) on automatics as opposed to standards? To take it a step further...if you had a 312 y-block from a '56 but equipped it with the heads from a '57 automatic, you'd be generating the output (in terms of CR, HP, torque) of a '57 engine...all other things being equal?

56 engines came with Load-o-matic vacuum only distributors and either Holly 2100 or 4100 carbs, 57's had mechanical/vacuum distributors and different carbs. The cams were mostly the same, and both 56 and 57 had the high ratio rockers.

Best regards,



Paul Menten

Meridian, Idaho

Concerning, the cams, the '57 cam is slightly better than the '56, but nowhere near aftermarket grinds available today.  On the street, you probably couldn't tell the difference between '56 and '57 cams.  4 barrel '56 312s were rated 225 HP, in '57 they were rated 245.

John - "The Hoosier Hurricane"

Good question Joey... I doubt Ford had different heads for the different compression ratios between manual and auto transmissions (in the same model year). Anybody got ideas??





Johnson Rod



Southern California

Actually, it looks like that's exactly what Ford did. A 56 292 2bbl would have ECZ-B heads and the 56 4bbl had ECZ-C heads. They stopped that nonsense in 1957 - most engines had ECZ-G heads, including the truck 272 2bbl. The 57 F code engines had special heads, but they're rare.

Best regards,



Paul Menten

Meridian, Idaho