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Old 07-29-2004, 04:29 PM
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Heads cracked in exhaust crossover

I have a pair of 305 #416 castings that are cracked through the exhaust crossovers. Other than that, the heads are good.

Is there any way to fill the the crossovers (I always block them on my propane engines) so that the cracks don't allow coolant to dribble into the ports? I thought of Epoxy, but that seems unlikely to last considering the temperature at the exhaust port side (once in the crossover, the water passages around the passage might keep the Epoxy from burning, but it still seems pretty iffy).

I also have a pair of 267 heads I could port and use (my truck engine is a 305 with .020" decked block and flat-tops), but the chambers are very tight around the intakes (3.5" bore versus 3.75), and I don't know how far they could be unshrouded before hitting the water jacket.

Any suggestions, or are these heads just handy places to store valves?

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Old 07-29-2004, 07:46 PM
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To properly repair your cracked heads, they would either need to be pinned, or welded. Epoxy will not work on an exhaust port areas as it's too hot, and would not hold water anyway.

Your 267 heads are probably 601's. Check the last three digits of the casting number. If they are, they are the same as 305 heads. As a matter of fact, I use them in performance applications.
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Old 07-29-2004, 09:54 PM
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You can fill the exhaust crossovers with Block Rock. The same stuff that is poured into water jackets to stiffen up a block...
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Old 08-02-2004, 01:44 PM
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The Block Rock will take the heat on the exhaust port side?

Also, do you know what it is based on, i.e. some form of masonry, or something I can carve with a carbide blade on a die grinder?

I figure it would probably help exhaust flow on the middle cylinders if this material was smoothly blended into the port (ie not proud or down the heat riser-passage).

Theone great advantage to these cracked heads is that they actually fit -the pair I am using right now fit poorly and so cause manifold sealing problems (I hate the idea of removing the dowels to improve alignment).
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