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Head fitment issues....Just picked up this block. Installing a set of dart 360 heads....don't have them yet, Dart said they'd work. Pic is of a standard gen 4 china head I just laid on the deck....I'd think they'd be the same? Why is it the top of the deck/block doesn't meet up with the head properly and overhang? Head bolt holes line up perfect. Heads are on the dowels. What the heck am I missing? Is this normal for a BBC? I'm not seasoned in the big Chevy world and why I'm asking. Always been a small block fella. Thanks
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Something is definitely off. This is my 10.200 tall deck Gen IV block with Dart 355CNC heads installed. Can you provide better pics from different angles, including the deck and head surfaces?

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I can only assume RP stands for Rectangle Port? Or did it mean RePosition? Chevy might have moved the heads inward due to a block change?

I wonder if the issue with that block lies in the fact that the front and rear valley walls are shorter on that block than the Gen IV?
 

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I'm not sure. Maybe this is a 10.2 tall deck gen VI thing? A Merlin or equivalent block like the ones in your pic wouldn't need a spacer. Just weird shit. I'm glad they make a spacer to correct it tho.
 

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raised port head, some aftermarket heads with raised ports ie dart and brodix 20* heads, require use of a china wall spacer. I dont know why you are having trouble with a "standard" head. maybe its the block.
 

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Same issue. With a dart block and head. Called dart about it and they acted like they had no clue what I was talking about. Ended up making my own spacers.
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STRANGE, you could measure from the pan rail to the intake support rail where the head is overhanging. Should be 11.03 or so inches, 280.2 mm. That is the dimension I have for Gen IV, V and VI blocks.
 

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I had to do the same thing with mine. I made some aluminum spacers and pinned them into the block. No problems to date.

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Wolf, that is why I gave him the specs to see if the rail had been cut down?
 

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I know my SD has had the deck severely lowered. Maybe this has been done here as well. AS you can see, my SD block is cut right down to the top waterpump holes to where there are witness marks on the deck.
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I keep thinking about my geometry!!!
This would make me worry about stuff failing from the wrong alignment!!!


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My Dart 10.2 has the same overhang. I just make end rail gaskets myself out of a thick section of reinforced rubber that is from a truck mud flap.Shaved on the ends for the taper. All pending on what intake gasket thickness after seat and crush. Measure away. This way i know for a fact the intake is properly sealed on the flange side.
 

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Do you have a rotating assembly in it if not I’d measure from crank journal to top of deck to make sure block hasn’t been decked alot
 

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That's nothing....you should see the overhang on my 10.7 brodix block with my 12* profilers. I had to make a china wall spacer that's over 1" tall....it's called engine building.....nothing is ever just a "bolt on"......
 
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