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By Dave C - 5 Years Ago
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I have a 312 block that I plan to use in my 55 Victoria. In sonic testing the bores I am anywhere from .238 on thick side to .195 on thin side. The engine has already been bored to .040 over to 3.840.
The engine was a re-manufactured out of a T bird at some point. During tear down bearings looked perfect and cylinders had been greased to prevent rust. Heads were not on it when I got it. After having it vatted I used a honing brush and cylinders cleaned up nice but show some rust stains NOT pitted.
I'm seriously considering just getting new pistons and doing a rebuild.
Anyone have any negatives about just a refresh or will I be pushing the limits on cylinder walls if I go out to .060 over? Sonic test was on 3 cylinders, but I will do them all to be safe.
No the main bolt holes are not cracked, block actually looks really nice.
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By Joe-JDC - 5 Years Ago
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Make sure your sonic tester transducer head has an arc to match the radius of the bore. Otherwise the readings will be a false high. Most engine builders will be happy with anything over .125" after boring and finish hone. You can get by with less on the non thrust walls. Joe-JDC
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By Dave C - 5 Years Ago
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Thanks Joe.. I'm good with the sonic tester..
I was thinking I was good. A few years back I was told by Kieth Black .100 minimum. But that was with a solid aluminum block with sleeves..
Dave
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By MoonShadow - 5 Years Ago
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Ted told me a minimum of .120 for a McCullouch application.
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By pegleg - 5 Years Ago
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We're all in the same ballpark at .125. I would not bore it any more than you need to as it is possible that there are area missed during the sonic test that are less than the .195 quoted.
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By Dave C - 5 Years Ago
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All is good it seems.
After brush honing the cylinders cleaned up very nice. So nice in fact that I'm not going to bore it any at all.
There was absolutely no ridge at the top of the cylinder and no rust anywhere else. I was amazed at how well it cleaned up.
Now my dilemma is whether to go with a 292 rod and custom pistons or just rebuild the 312 rods and go with a replacement cast piston.
I like the idea of doing as Ted has in using a custom piston with 1.2mm rings but my head keeps saying to use a stock type piston as I don't plan
to do any racing with it. It will just be a cruiser, and I want to be able to drive it across country if I feel like it. So a full bore stroker motor is not really necessary.
Thanks guy's
Dave.
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By charliemccraney - 5 Years Ago
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Within reason, things that benefit racing can be a benefit for the street. The thinner rings will result in less friction and the piston will most likely be lighter. That should help power and economy. It should be fine as far as reliability because modern production engines use thinner rings than clunky old vintage engines. I have about 20000 miles on mine so far, including several multi-state trips and still going strong.
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By cos - 5 Years Ago
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Hello Did you run a bore gauge down cylinders to check taper? Probably fine as it has been already bored once. But a basic step.
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By Dave C - 5 Years Ago
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Yes, Bore is straight. It's in the solution to get the rust out of water jackets, (I hope).
I'm using electrolysis to de-rust.
Just doing this as a preventative measure.
Dave
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