Thread: 400 steam holes

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I got my 400 back from the machine shop today. My ? is the steam holes in the the aftermarket head the machine shop said that he has ran them both ways steam holes and no steam holes with no real diff. So i tells a friend at work about it and said i am gonna over heat without them is or is their not any diff. I belive the machine shop cause i guess they nomore about it than i do maybe some facts i should know any suggestions

You will definately need the steam holes in the head's , I personally have seen a 400 overheat and cause damage when a aftermarket set of head's were installed. You could blow a head gasket and cause all sorts of engine problems. The cylinders need the extra cooling because of the large bore!

NOT THAT MY OPINION IS ANY BETTER THAN ANYONE ELSES BUT ACCORDING TO HENDRIX MOTORSPORTS IF YOUR PLANNING ON STREET DRIVING A 400SBC IT IS EXTREMELY IMPORTANT TO MAKE SURE THAT THE HEADS, STOCK OR AFTERMARKET, AND HEAD GASKETS HAVE HOLES MACHINED IN THEM MATCHING THE CYLINDER BLOCKS STEAM HOLES. ANY ENGINE THAT IS GOING TO BE PRIMARILY DRIVEN ABOVE 3,500RPM IT IS NOT NECESSARY DUE TO HIGHER CIRCULATION OF WATER FROM THE PUMP SPINNING FASTER ELIMINATES ANY AIR POCKETS IN STEAM HOLE AREA OF THE COOLING SYSTEM

I put edelbrock victor jr. heads on my 377 which is the version with the 400 block and 350 crank. Edelbrock recommends not putting the upper steam holes in the beads, so I went on their recommendation. I am down here in south Louisiana and it gets pretty hot here. Have run the car on the street without any overheating problems at all. I am running 11.4:compression on pump gas, it runs 180 all the time, even in stop and go traffic.
It's my guess with iron holes you might need the steam holes, with aluminum you might not need them. Go with your after market head manufacturer.