312 block
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312 block
In the middle of rebuilding an original 312 for a '56 TBird discovered the block seems to have encountered extreme heat at some point in its past and torquing the crank has uncovered cracked journals.
(1) Looking for source for a good 312 block, or
(2) compatability in converting to a 292 in terms of salvaging parts already reconditioned (eg crank) or purchased for the 312 rebuild?
Thanks in advance for any help out there.
(1) Looking for source for a good 312 block, or
(2) compatability in converting to a 292 in terms of salvaging parts already reconditioned (eg crank) or purchased for the 312 rebuild?
Thanks in advance for any help out there.
Posting Guru
Joined: Mar 2002
Posts: 2,070
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From: Boise, Idaho
TexasTBird, If you don't mind getting the crank ground again, the main journals can be turned down to fit a 292. If you don't care about originality, I'd find a mid-50's 292 block and bore it out to the 312 bore, and turn the crank's journals down to fit the 292 block.
Some experienced y-block builders would recommend the 292 block and 272 block more than the 312 block: less tendency to crack the main webs.
There are a lot of ways that things can go wrong building a y-block, especially with the bottom end. The lengths of bolts is a major issue. Some of the bolts that hold the main caps are longer than others. If you put a long bolt into a cap that needed short bolts, you'll ruin your block.
Also, Ford raised the torque specs for main journals on the 312 for a short time. When they had engines breaking because of the increased torque specs, they lowered the spec back to the original 272-292 specs.
I'd try to find a 56-59 292 block that's original. I'd also try to find a very experienced y-block builder to do the block re-work.
Some experienced y-block builders would recommend the 292 block and 272 block more than the 312 block: less tendency to crack the main webs.
There are a lot of ways that things can go wrong building a y-block, especially with the bottom end. The lengths of bolts is a major issue. Some of the bolts that hold the main caps are longer than others. If you put a long bolt into a cap that needed short bolts, you'll ruin your block.
Also, Ford raised the torque specs for main journals on the 312 for a short time. When they had engines breaking because of the increased torque specs, they lowered the spec back to the original 272-292 specs.
I'd try to find a 56-59 292 block that's original. I'd also try to find a very experienced y-block builder to do the block re-work.
Posting Guru
Joined: Jul 2001
Posts: 2,119
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From: Southern New Hampshire
I hope that you did not torque per Motors Manual or others that have the wrong spec of 120-130 ft lbs for a 312.
Correct is 100 ft lbs maximum.
The 312 crank can be turned for a 292 block which is what many racers do as it provides a stronger low end.
Correct is 100 ft lbs maximum.
The 312 crank can be turned for a 292 block which is what many racers do as it provides a stronger low end.
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Thanks for the quick response. Your feedback is much appreciated and consistent with others I've received and read on
this forum.
Seems the 292 route is the wize approach, although I was hoping to keep things as original as possible since this is a really nice ride. Glad to learn internals can be reused. Have not found a Y block guru in the central texas area yet, but my search continues...
Any help on a reliable source for a '56 292 block would also be much appreciated?
this forum.
Seems the 292 route is the wize approach, although I was hoping to keep things as original as possible since this is a really nice ride. Glad to learn internals can be reused. Have not found a Y block guru in the central texas area yet, but my search continues...
Any help on a reliable source for a '56 292 block would also be much appreciated?
Laughing Gas
Joined: Feb 2004
Posts: 1,013
Likes: 2
if you decide to turn your crank you also have to turn down your rear seal the same amount.if your engine was built before may 56 the crank grinder can do it.after that date an oil slinger was cast into the crank in front of the rear seal.the crank grinder does not have a wheel that will fit in there.you will have to have it turned in a lathe.just a minor job,but something you need to know.
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