I have a choice of building a car with a 312 or 256. To me, it is clear at first that the 312 is 20% bigger, why would I want a 256? But a friend said I was better off with anything but the 312, it was a low power and high maintenance engine. But...thats 56 cu in smaller! And some sources say as just as much horsepower! Would it make sense to use the (supposedly) more stable 256? ( the friend is really sure, and he seems to know Fords...yard full of F-100s and Galaxies and all)



Also, can anyone tell me the outer dimensions of a Y-Block? No one seems to know, or care to know, and I don;t have either engine in hand to measure.


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People should not be afraid of their government, a government should be afraid of the people.

--Alan Moore

If I can take it apart before making the absolute decision, the 312 will be my choice. Early 312s tended to crack at the mains due to a high torque spec for the main bolts. I believe the spec was corrected for 57 so if it's a 57 or later engine it's probably good. And if it's not cracked, it will be fine. Other than that, I can't think of a reason that a 312 will be any less stable.



I don't have engine dimensions readily available but I can get them if no one else has them handy.


Lawrenceville, GA

Go withthe 312 for sure.  

A stock or modified 312 is a very god running engine.  There should be no reliability differences as they are the same basic engine. An with a modern rebuild there are olmost no relibility problems with a mild Y-block.

The only down falls of a 312 are: possible cracked block, the main bearings cost more, and it is harder to get a good rear main seal than a 292.  The 312 should have the better flowing cylinder heads and much better compression ratio.

The 256 would be harder to find pistons and rings for, super low compression, horrible cylinder heads, and most of all, it is only a 256!  Way to small with no torque at all compared to a 312.

Pat Fleischman

Thanks for the confirmation. Could you get the dimensions? I am doing some super-custom stuff, so I could use both a measurement at the start of the skirting and at the top, and after the cylinder banks. I am not so worried about the length, but that would be helpful, too.



It's a shame you say it was fixed in '57, I was looking at a '56! I'll just have to take precautions.

In one way I take that as a good sign, that the engine was so full of torque it posed a danger to itself

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People should not be afraid of their government, a government should be afraid of the people.

--Alan Moore

The torque of the engine was not the problem! Problem was the the factory torque spec for the main cap bolts was too high and caused cracks in the block main bearing web.

Glen Henderson



Freedom is not Free

Letohatchee, AL

The 256 in my opinion is not in the same league as a 312. The 312 has larger main bearings which I feel are stronger than the 256, makes way............................more HP and torque stock than the 256 that's been somewhat built up and the 312 is................ tuff as nails. Been around these engines since the late 50s and the 292 and 312s are the ones that blistered the GM camp bad....................... thru the 50s and into the 60s as well. I'd go for the 312 if you can find one. The one in the 56 you talked about may be a good one too. If the main are good don't torque over 95 Lbs, build it and have a blast!!!!!

-Gary Burnette-

Here is couple of links with info on the y-blocks

http://www.secondchancegarage.com/public/414.cfm

http://www.fairlane.nu/spec/y-block-dimensions.htm
marv

Ima thinking your "friend" has his eye on that 312" so he's trying to get you to go for the 256"...lol. Listen to the other guys on this thread... you will be a happy camper.

BOB

Duhhhhhh ....

Doing Fords for 45 years. '56 Customline Victoria

E.J. in Havana FL

Many of the ’54 model 239 and 256 engines also had some manufacturing differences thus making these two engines difficult to interchange parts with from the ’55 and later 272, 292, and 312 engines.  Some of these differences include larger sized journals on the camshafts, larger camshaft bores, tanged oil pump, different design oil pump shaft, 13 teeth on the distributor gear instead of 14, and a smaller water pump with a corresponding timing cover.  Seems like the fuel pump also had a different mounting pattern.  The 312 is the obvious choice if the block checks out.

 

But I recently did see a 256 engine with a late model camshaft and the bearings were special.  Extra thick so that the smaller journal camshaft would fit in place which also allowed the use of the later model 14 tooth geared distributor.

Lorena, Texas (South of Waco)