magiemae (9/15/2015)
........ The number on the heads are ED - ECZ-C with a 1.78 valve, this is were I get confused from what I read the heads are from a 1956 truck 272 cu.in. To my knowledge this is the original and has not been altered, although it appears that one of the heads have been taken off at sometime.
I can only guess at what the rules were for the heads that were supplied for the marine engines. Where the cylinder heads for the cars and trucks are pretty much defined either by year or cubic inch, the marine engines would appear to be more dictated by the required horsepower or torque. As such, it’s possible that the 312 engines simply received a smaller valve head to get the torque numbers higher or to actually limit the rpm capability. I’ve dealt with several 312 marine engines and the cylinder head choices for those seem to be all over the map as the intake valve sizes are varied.
Here’s the link to a recent thread showing some pictures of the marine valley covers. I suspect your cover has the air cleaner built into it under the intake manifold. Those particular covers are missing the fuel arrester bonnets quite frequently when they arrive here.
http://forums.y-blocksforever.com/FindPost116597.aspx