I have a set of ported heads ready to go on, but the guy I bought them from partially welded the end coolant passages, what I need to know is whether or not I have to open them back up fully or is the partial hole enough for adequate cooling as the hole on the head is bigger than the one on the block as it is?

Here is a picture of the passages with the gasket opening traced in red marker.

 

hmm good question more like why did he do it? id day have them opened back up

 

He did it because he was going to install them on a standard SBC, L98 I think, but never did.

 

Anyone else?

 

Grind em out with a dremel, and be CAREFUL not to nick anything else in the process.

 

Yea I agree with HardcoreRM125 about grind those out. They need to be open like stock.

 

Unfortunately, you should probably open it back up, and they take the heads and have them resurfaced at a machine shop. Grinding it out and slapping the heads on is just asking for a blown gasket...

 

Just take it to the machine shop and they will mill out that section - then lightly lap the burrs off the edge. They should not have to re-surface the heads.