340 help

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KB9GIB

KB9GIB

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Hi Just got this 340 8/67 look at the head surface top right side front and top left rear looks like it has some sort of plug in it is this right. Thanks KB9GIB

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I just looked at my 71 340 block, nothing like that, completely smooth. The gasket covers it, likely nothing to worry about.
 
Demonic said:
I just looked at my 71 340 block, nothing like that, completely smooth. The gasket covers it, likely nothing to worry about.
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If you look at the 318 poly block you will see 2 of those ports on each side.

To use wedge heads on these old 318 blocks you have to plug these holes.

You could build a 340 poly out of this block. How kool would that be?

Of course the early 318 block are so thick walled they can be bored to 340 size anyway.
 
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KB9GIB, do you have a pic of the casting date/engine size on the side of the block? Im curious as to the casting date, August 1967??
 
Being an early cast 340 block, I think that is how they choose to block those two ports off. Later castings they were smooth to the surface of the block.
 
I just looked, and my '71 360 is completely different, just the 2 oil passages. Never noticed that before. What were the ports for? Different coolant paths for the poly heads?
 
I have never seen that before. I will have to check my 340 blocks and see if any are like that. I think the earliest I have is a 68 though.
 
This is a 1973 340 block for reference

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Typo on my part. I did not have my glasses on. Boy this is a rough crowd this morning. Casting date 5-25-73
Lol
 
Hey, I was excited! Maybe you had a one of one 74 340 block.
That block is clean, was it blasted with steel shot? I had my last one done with that and its way better than a hot tank.
 
yellow rose said:
Measure the deck height. I'd bet it's 9.625 or a bit taller.
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I dropped the block off today to have it Magna flux if that’s good I will have to put together a rotating assembly any suggestions would be appreciated as it was just a bare block. just want a good driving motor. Thanks KB9GIB
 
KB9GIB said:
I dropped the block off today to have it Magna flux if that’s good I will have to put together a rotating assembly any suggestions would be appreciated as it was just a bare block. just want a good driving motor. Thanks KB9GIB
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Do you want more HP than a standard 340? Is this for daily driving, cruising, all-out drag racing, hauling moonshine? Being installed in an A body or B-body or an Imperial? (I know what I do and like but that may not match what you want to do.) NM9S
 
I have a 67 block with the plug in it. but mine is cracked around the plug which caused the oil and water to mix. I think I'm going to have it welded.
 
1340busa said:
I have a 67 block with the plug in it. but mine is cracked around the plug which caused the oil and water to mix. I think I'm going to have it welded.
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We picked up the block from the machine shop they said it was a good block. I have never dealt with the early 340 so I was stumped when I seen what looked like plugs in the block but with the good help from all on here they help me out. Thanks again KB9GIB southern Illinois.
 
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