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By randyh - 14 Years Ago
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Shop called today, the 312 block that I planned on rebuilding is cracked at two main bearing bolt holes. Looking for a good 312 block to rebuild. The original block has a casting date code of 6 B S. I know it probably is asking too much but I would like to find a block with 6 B casting code. If anyone can help me out please let me know. Randy
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By PF Arcand - 14 Years Ago
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We've heard this unfortunate story before. The 312 blocks mains were over tightened at some point. Early 1956 manuals specified a torque that was well above what was needed. Did your shop actually get to the assembly point? 90 to 95 lbs is plenty, no more!
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By PF Arcand - 14 Years Ago
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Randy: If you just can't locate a replacement 312 block, it's possible to convert a 292 to 312 bore etc. However, additional machining is involved to the crankshaft mains & seal area. The specs should be available over at www.ford-y-block.com
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By Hoosier Hurricane - 14 Years Ago
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Randy: Since you are casting date conscious, don't throw away your present block yet. I have used blocks with cracks in the main bolt holes by drilling and tapping a little deeper and using longer bolts. If the cracks are on the oil passage side, be careful that you don't drill so deep that the longer bolt blocks the side oil passage. I have even done this on my drag engine. Have not experienced any main web failures. As Paul mentioned, the '56 mains were overtorqued from the factory, so it is possible it has run 50+ years with the cracks.
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By aussiebill - 14 Years Ago
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Hoosier Hurricane (8/11/2011)
Randy: Since you are casting date conscious, don't throw away your present block yet. I have used blocks with cracks in the main bolt holes by drilling and tapping a little deeper and using longer bolts. If the cracks are on the oil passage side, be careful that you don't drill so deep that the longer bolt blocks the side oil passage. I have even done this on my drag engine. Have not experienced any main web failures. As Paul mentioned, the '56 mains were overtorqued from the factory, so it is possible it has run 50+ years with the cracks. Yes john, i agree with you, they are still very usable and retapped as you point out will keep on going.
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By randyh - 14 Years Ago
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I didn't make it over to shop today to look at it but talked to owner, I heard original message wrong, all ten bolt holes have radial cracks starting at threads. Fortunately? I was having it checked for cracks before doing any machining. This is my father's Phase I supecharger car so I wanted to use correct block but, I don't want to risk putting too much into a block that may cause trouble in future, I know my father will want to put his foot into at least once more. Do you think it will hold up with studs installed deeper if run hard? Randy
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By paul2748 - 14 Years Ago
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Are the cracks on the same bearing? If only one per bearing you may be able to fix it. I had the same situation. However, the guy doing the rebuild said he could weld the cracks, drill and tap the bolt holes deeper and use studs (ARP) rather than bolts. I have been running the engine for three years now and took two long trips, buzzing along at about 3thou rpm and the motor is running great (knock on wood).
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By randyh - 14 Years Ago
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Still haven't seen block,talked to shop again they tell me that some of the holes have multiple cracks. I can't get to shop until Monday, I'll post a picture of worse one once I see it. Randy
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By The Master Cylinder - 14 Years Ago
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Hoosier Hurricane (8/11/2011)
Randy:
Since you are casting date conscious, don't throw away your present block yet. I have used blocks with cracks in the main bolt holes by drilling and tapping a little deeper and using longer bolts. If the cracks are on the oil passage side, be careful that you don't drill so deep that the longer bolt blocks the side oil passage. I have even done this on my drag engine. Have not experienced any main web failures. As Paul mentioned, the '56 mains were overtorqued from the factory, so it is possible it has run 50+ years with the cracks.
That there is some information... Thanks John
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By PF Arcand - 14 Years Ago
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Randy: With the follow up info you supplied, it sounds like your block is unfortunately toast.. I might be mistaken, but I think you need the correct year casting letters for a start. The chart from www.Ford-y-block.com lists 1957 312 blocks as ECZ- 6015-C. With ECZ marked main caps. However, if equipped with EBU main caps it will be a 292. Also given shipping costs & difficulties,what area are you in?
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By randyh - 14 Years Ago
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Paul, I talked with another member yesterday, the 312 that he has for sale, which he verified by pulling the transmission, was cast in November 56 a little over a month earlier then mine but i doubt I can get any closer than that so I am going to pick it up next weekend and hope the block is not cracked. I am a little east of Pittsburgh, PA so it will be a little over an 8 hour drive. Randy
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By randyh - 14 Years Ago
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Here is a picture of the worst location, I counted 4 cracks in it: 12:00, 4:00, 7:00, 9:00. The worst ones at 4:00 and 9:00 go all the way to side and then can be seen 1/2" along sides. I guess this block is junk. 
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By RB - 14 Years Ago
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That is quite a co-incidence that you posted exactly at 312 pm
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By PF Arcand - 14 Years Ago
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Randy: thats a fairly long drive to look at it, so I'd suggest taking some tools & cleaning stuff with you. No point in hauling another dud block all the way back. Take the pan off & caps, & check the main areas at least with a magnifing glass.
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By randyh - 14 Years Ago
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Made the trip on friday and unfortunately the block was cracked. Only pulled #2 and #4 caps and found two cracks from the bolt hole on the filter side of #4. Too bad, another 312 block bites the dust, so I am back to looking. Randy
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By Jeffs54Merc - 14 Years Ago
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Randy, Once again, I am sorry you made that long trip for nothing. I am going to disassemble the engine and sell the parts. I wish this could have been your "needle in the haystack", but it wasn't. Just let me know your address and I will send you the oil pan tube.
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