Sonic Test

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What exactly is "minimum thickness" is a point of debate. I own a good tester and I use .120 as a minimum thickness on major thrust (that's the right side wall of each hole when looking down on the engine from the rear). Some go .150, some say .200. It should be between your machinist and you, and thicker the better. Sleeve holes if you dont have extra blocks and fine a thin one or two. If you can scan and post the results it might be easier for others to comment.

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What exactly is "minimum thickness" is a point of debate. I own a good tester and I use .120 as a minimum thickness on major thrust (that's the right side wall of each hole when looking down on the engine from the rear). Some go .150, some say .200. It should be between your machinist and you, and thicker the better. Sleeve holes if you dont have extra blocks and fine a thin one or two. If you can scan and post the results it might be easier for others to comment.

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I have seen 400 blocks raced(N/A only) sucessfully with .120 wall thickness on the major thrust for hundreds of runs, these where 13.0 to 1 motors tuned properly for no detonation on good quality race gas One of them had a small spot on the front of one cylinder that sonic .090 at the top and .072 at the bottom of that cylinder, I recommended not using it but he did anyways, sucessfully for four years chasing NHRA points in SG all over the country

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Okay just so I understand this. Lets use the OP's numbers and assume they are for a block that has not been bored yet. I notice that the #1 hole is off in one direction (I assume core shift) - thrust side 173 and non thrust 180. Can you just push the new bore toward the non-thrust side to cut as little as possible from the thrust side. How much movement of the bore can a block sustain without having geometry problems relative to the crank, rods, pistons etc.

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How much did they charge for the sonic check??

Also, they usually check it in at least 2 points up and down the bore. They've only done yours in one!

For the sake of a few thou I wouldn't offset the bores.

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Hoping to get in the mid-low nines in a lightened A-body- I guess around 700 hp should do it

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I would think with the level of performance desired you would be advised to get an aftermarket block. I am sure you will hear countless people tell you that they did it with no problem, but you are asking a lot of the factory piece.

MB

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don`t have my sheet in front of me but when I called DLI they said my block would make a good flower pot...............10 years later and SEVERAL 7000+ rpm passes it`s still goin strong.

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Yea, and they told me that after I spent 15K with them (in the mid 1980's!) that my SS/DA Hemi would be good to go until the end of the racing season....And it promptly spun all the main bearings on the 3rd pass.

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IMO the block is ok for your intended use. Not perfect, but usable. It might be better to sleeve #5 as it will be under .100 on the pin axis and 700hp will move the block around. There are no 100% promises with 40yr old parts. But with good parts and preparation, good machining, and good tuning it should last fine. If you're at all nervous go with a 1/2 fill and you won't have a problem. I'm curious why you aren't using them for the build if they obviously have the quality equipment and enough motivation to want to check the important things.

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Here's the test results what do you guys think?

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I've had some time to think about your numbers and compare to my data and I think you might be better off than it appears. While my tester is a knockoff and not the spendy one it does seem to work okay and I verify it on every block I test to see if it's reading correctly. I do this by measuring an area on the block that can also be directly measured with a caliper or micrometer. If you add your major thrust and minor thrust thicknesses to your bore diameter you get a sort of outer diameter of the bore on the thrust axis. I say sort of because it's based on minimum measurements that may not be directly across from each other and an average of thicknesses up and down the bore would be more representative of what the cylinder is really like. That said, your numbers produce an average OD of 4.727" and I've never seen one that small in any of the 14 400's and 440's I've tested. The 4 400's I've tested average 4.796" and that number might be small because 2 of them were 1978 models that were the 2 smallest OD's of all the 400/440 blocks I've tested. FWIW, my '72 400 was 4.809". The 440's I've tested averaged 4.812" and the numbers were all close enough together that I can confidently say that a 440 will be about 4.8" without even testing it.
Now it could be that my tester reads thick but then that means that the couple of blocks I've measured that produced numbers in the 0.110-0.120" range would have to be extremely thin. It could also be that you have a block that is terribly rusted but I doubt it. I'm starting to doubt the calibration of the tester used on your block and it would be nice if others who have data would speak up and agree or tell me I'm wrong.
Additional info to toss out there for discussion if anyone is interested: 3 motorhome 413 blocks (all '72-'73) averaged 4.732", the 3 smallest of the 14 400/440 blocks were ALL 1978 models and were 4.77x", a 1977 440 was 4.836" and was second biggest of all. Some day I'll get around to testing the rest of the 400's and 440's I have around but they're hard to get to now.

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Here's the test results what do you guys think?

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I've had some time to think about your numbers and compare to my data and I think you might be better off than it appears. While my tester is a knockoff and not the spendy one it does seem to work okay and I verify it on every block I test to see if it's reading correctly. I do this by measuring an area on the block that can also be directly measured with a caliper or micrometer. If you add your major thrust and minor thrust thicknesses to your bore diameter you get a sort of outer diameter of the bore on the thrust axis. I say sort of because it's based on minimum measurements that may not be directly across from each other and an average of thicknesses up and down the bore would be more representative of what the cylinder is really like. That said, your numbers produce an average OD of 4.727" and I've never seen one that small in any of the 14 400's and 440's I've tested. The 4 400's I've tested average 4.796" and that number might be small because 2 of them were 1978 models that were the 2 smallest OD's of all the 400/440 blocks I've tested. FWIW, my '72 400 was 4.809". The 440's I've tested averaged 4.812" and the numbers were all close enough together that I can confidently say that a 440 will be about 4.8" without even testing it.
Now it could be that my tester reads thick but then that means that the couple of blocks I've measured that produced numbers in the 0.110-0.120" range would have to be extremely thin. It could also be that you have a block that is terribly rusted but I doubt it. I'm starting to doubt the calibration of the tester used on your block and it would be nice if others who have data would speak up and agree or tell me I'm wrong.
Additional info to toss out there for discussion if anyone is interested: 3 motorhome 413 blocks (all '72-'73) averaged 4.732", the 3 smallest of the 14 400/440 blocks were ALL 1978 models and were 4.77x", a 1977 440 was 4.836" and was second biggest of all. Some day I'll get around to testing the rest of the 400's and 440's I have around but they're hard to get to now.

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